1306 lines
51 KiB
C
1306 lines
51 KiB
C
/*
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**
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** The author disclaims copyright to this source code. In place of
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** a legal notice, here is a blessing:
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**
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** May you do good and not evil.
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** May you find forgiveness for yourself and forgive others.
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** May you share freely, never taking more than you give.
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**
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*************************************************************************
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** This file contains code used by the compiler to add foreign key
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** support to compiled SQL statements.
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*/
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#include "sqliteInt.h"
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#ifndef SQLITE_OMIT_FOREIGN_KEY
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#ifndef SQLITE_OMIT_TRIGGER
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/*
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** Deferred and Immediate FKs
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** --------------------------
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**
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** Foreign keys in SQLite come in two flavours: deferred and immediate.
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** If an immediate foreign key constraint is violated,
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** SQLITE_CONSTRAINT_FOREIGNKEY is returned and the current
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** statement transaction rolled back. If a
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** deferred foreign key constraint is violated, no action is taken
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** immediately. However if the application attempts to commit the
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** transaction before fixing the constraint violation, the attempt fails.
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**
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** Deferred constraints are implemented using a simple counter associated
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** with the database handle. The counter is set to zero each time a
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** database transaction is opened. Each time a statement is executed
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** that causes a foreign key violation, the counter is incremented. Each
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** time a statement is executed that removes an existing violation from
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** the database, the counter is decremented. When the transaction is
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** committed, the commit fails if the current value of the counter is
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** greater than zero. This scheme has two big drawbacks:
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**
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** * When a commit fails due to a deferred foreign key constraint,
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** there is no way to tell which foreign constraint is not satisfied,
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** or which row it is not satisfied for.
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**
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** * If the database contains foreign key violations when the
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** transaction is opened, this may cause the mechanism to malfunction.
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**
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** Despite these problems, this approach is adopted as it seems simpler
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** than the alternatives.
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**
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** INSERT operations:
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**
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** I.1) For each FK for which the table is the child table, search
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** the parent table for a match. If none is found increment the
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** constraint counter.
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**
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** I.2) For each FK for which the table is the parent table,
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** search the child table for rows that correspond to the new
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** row in the parent table. Decrement the counter for each row
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** found (as the constraint is now satisfied).
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**
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** DELETE operations:
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**
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** D.1) For each FK for which the table is the child table,
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** search the parent table for a row that corresponds to the
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** deleted row in the child table. If such a row is not found,
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** decrement the counter.
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**
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** D.2) For each FK for which the table is the parent table, search
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** the child table for rows that correspond to the deleted row
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** in the parent table. For each found increment the counter.
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**
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** UPDATE operations:
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**
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** An UPDATE command requires that all 4 steps above are taken, but only
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** for FK constraints for which the affected columns are actually
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** modified (values must be compared at runtime).
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**
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** Note that I.1 and D.1 are very similar operations, as are I.2 and D.2.
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** This simplifies the implementation a bit.
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**
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** For the purposes of immediate FK constraints, the OR REPLACE conflict
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** resolution is considered to delete rows before the new row is inserted.
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** If a delete caused by OR REPLACE violates an FK constraint, an exception
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** is thrown, even if the FK constraint would be satisfied after the new
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** row is inserted.
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**
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** Immediate constraints are usually handled similarly. The only difference
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** is that the counter used is stored as part of each individual statement
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** object (struct Vdbe). If, after the statement has run, its immediate
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** constraint counter is greater than zero,
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** it returns SQLITE_CONSTRAINT_FOREIGNKEY
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** and the statement transaction is rolled back. An exception is an INSERT
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** statement that inserts a single row only (no triggers). In this case,
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** instead of using a counter, an exception is thrown immediately if the
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** INSERT violates a foreign key constraint. This is necessary as such
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** an INSERT does not open a statement transaction.
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**
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** TODO: How should dropping a table be handled? How should renaming a
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** table be handled?
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**
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**
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** Query API Notes
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** ---------------
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**
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** Before coding an UPDATE or DELETE row operation, the code-generator
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** for those two operations needs to know whether or not the operation
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** requires any FK processing and, if so, which columns of the original
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** row are required by the FK processing VDBE code (i.e. if FKs were
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** implemented using triggers, which of the old.* columns would be
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** accessed). No information is required by the code-generator before
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** coding an INSERT operation. The functions used by the UPDATE/DELETE
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** generation code to query for this information are:
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**
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** sqlite3FkRequired() - Test to see if FK processing is required.
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** sqlite3FkOldmask() - Query for the set of required old.* columns.
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**
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**
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** Externally accessible module functions
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** --------------------------------------
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**
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** sqlite3FkCheck() - Check for foreign key violations.
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** sqlite3FkActions() - Code triggers for ON UPDATE/ON DELETE actions.
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** sqlite3FkDelete() - Delete an FKey structure.
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*/
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/*
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** VDBE Calling Convention
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** -----------------------
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**
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** Example:
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**
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** For the following INSERT statement:
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**
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** CREATE TABLE t1(a, b INTEGER PRIMARY KEY, c);
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** INSERT INTO t1 VALUES(1, 2, 3.1);
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**
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** Register (x): 2 (type integer)
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** Register (x+1): 1 (type integer)
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** Register (x+2): NULL (type NULL)
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** Register (x+3): 3.1 (type real)
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*/
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/*
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** A foreign key constraint requires that the key columns in the parent
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** table are collectively subject to a UNIQUE or PRIMARY KEY constraint.
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** Given that pParent is the parent table for foreign key constraint pFKey,
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** search the schema for a unique index on the parent key columns.
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**
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** If successful, zero is returned. If the parent key is an INTEGER PRIMARY
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** KEY column, then output variable *ppIdx is set to NULL. Otherwise, *ppIdx
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** is set to point to the unique index.
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**
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** If the parent key consists of a single column (the foreign key constraint
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** is not a composite foreign key), output variable *paiCol is set to NULL.
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** Otherwise, it is set to point to an allocated array of size N, where
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** N is the number of columns in the parent key. The first element of the
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** array is the index of the child table column that is mapped by the FK
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** constraint to the parent table column stored in the left-most column
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** of index *ppIdx. The second element of the array is the index of the
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** child table column that corresponds to the second left-most column of
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** *ppIdx, and so on.
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**
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** If the required index cannot be found, either because:
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**
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** 1) The named parent key columns do not exist, or
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**
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** 2) The named parent key columns do exist, but are not subject to a
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** UNIQUE or PRIMARY KEY constraint, or
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**
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** 3) No parent key columns were provided explicitly as part of the
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** foreign key definition, and the parent table does not have a
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** PRIMARY KEY, or
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**
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** 4) No parent key columns were provided explicitly as part of the
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** foreign key definition, and the PRIMARY KEY of the parent table
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** consists of a a different number of columns to the child key in
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** the child table.
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**
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** then non-zero is returned, and a "foreign key mismatch" error loaded
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** into pParse. If an OOM error occurs, non-zero is returned and the
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** pParse->db->mallocFailed flag is set.
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*/
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int sqlite3FkLocateIndex(
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Parse *pParse, /* Parse context to store any error in */
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Table *pParent, /* Parent table of FK constraint pFKey */
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FKey *pFKey, /* Foreign key to find index for */
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Index **ppIdx, /* OUT: Unique index on parent table */
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int **paiCol /* OUT: Map of index columns in pFKey */
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){
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Index *pIdx = 0; /* Value to return via *ppIdx */
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int *aiCol = 0; /* Value to return via *paiCol */
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int nCol = pFKey->nCol; /* Number of columns in parent key */
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char *zKey = pFKey->aCol[0].zCol; /* Name of left-most parent key column */
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/* The caller is responsible for zeroing output parameters. */
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assert( ppIdx && *ppIdx==0 );
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assert( !paiCol || *paiCol==0 );
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assert( pParse );
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/* If this is a non-composite (single column) foreign key, check if it
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** maps to the INTEGER PRIMARY KEY of table pParent. If so, leave *ppIdx
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** and *paiCol set to zero and return early.
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**
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** Otherwise, for a composite foreign key (more than one column), allocate
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** space for the aiCol array (returned via output parameter *paiCol).
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** Non-composite foreign keys do not require the aiCol array.
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*/
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if( nCol==1 ){
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/* The FK maps to the IPK if any of the following are true:
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**
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** 1) There is an INTEGER PRIMARY KEY column and the FK is implicitly
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** mapped to the primary key of table pParent, or
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** 2) The FK is explicitly mapped to a column declared as INTEGER
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** PRIMARY KEY.
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*/
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if( pParent->iPKey>=0 ){
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if( !zKey ) return 0;
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if( !sqlite3StrICmp(pParent->aCol[pParent->iPKey].zName, zKey) ) return 0;
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}
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}else if( paiCol ){
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assert( nCol>1 );
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aiCol = (int *)sqlite3DbMallocRaw(pParse->db, nCol*sizeof(int));
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if( !aiCol ) return 1;
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*paiCol = aiCol;
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}
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for(pIdx=pParent->pIndex; pIdx; pIdx=pIdx->pNext){
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if( pIdx->nColumn==nCol && pIdx->onError!=OE_None ){
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/* pIdx is a UNIQUE index (or a PRIMARY KEY) and has the right number
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** of columns. If each indexed column corresponds to a foreign key
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** column of pFKey, then this index is a winner. */
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if( zKey==0 ){
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/* If zKey is NULL, then this foreign key is implicitly mapped to
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** the PRIMARY KEY of table pParent. The PRIMARY KEY index may be
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** identified by the test (Index.autoIndex==2). */
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if( pIdx->autoIndex==2 ){
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if( aiCol ){
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int i;
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for(i=0; i<nCol; i++) aiCol[i] = pFKey->aCol[i].iFrom;
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}
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break;
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}
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}else{
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/* If zKey is non-NULL, then this foreign key was declared to
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** map to an explicit list of columns in table pParent. Check if this
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** index matches those columns. Also, check that the index uses
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** the default collation sequences for each column. */
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int i, j;
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for(i=0; i<nCol; i++){
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int iCol = pIdx->aiColumn[i]; /* Index of column in parent tbl */
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char *zDfltColl; /* Def. collation for column */
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char *zIdxCol; /* Name of indexed column */
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/* If the index uses a collation sequence that is different from
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** the default collation sequence for the column, this index is
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** unusable. Bail out early in this case. */
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zDfltColl = pParent->aCol[iCol].zColl;
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if( !zDfltColl ){
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zDfltColl = "BINARY";
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}
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if( sqlite3StrICmp(pIdx->azColl[i], zDfltColl) ) break;
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zIdxCol = pParent->aCol[iCol].zName;
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for(j=0; j<nCol; j++){
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if( sqlite3StrICmp(pFKey->aCol[j].zCol, zIdxCol)==0 ){
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if( aiCol ) aiCol[i] = pFKey->aCol[j].iFrom;
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break;
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}
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}
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if( j==nCol ) break;
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}
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if( i==nCol ) break; /* pIdx is usable */
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}
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}
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}
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if( !pIdx ){
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if( !pParse->disableTriggers ){
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sqlite3ErrorMsg(pParse,
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"foreign key mismatch - \"%w\" referencing \"%w\"",
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pFKey->pFrom->zName, pFKey->zTo);
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}
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sqlite3DbFree(pParse->db, aiCol);
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return 1;
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}
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*ppIdx = pIdx;
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return 0;
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}
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/*
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** This function is called when a row is inserted into or deleted from the
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** child table of foreign key constraint pFKey. If an SQL UPDATE is executed
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** on the child table of pFKey, this function is invoked twice for each row
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** affected - once to "delete" the old row, and then again to "insert" the
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** new row.
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**
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** Each time it is called, this function generates VDBE code to locate the
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** row in the parent table that corresponds to the row being inserted into
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** or deleted from the child table. If the parent row can be found, no
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** special action is taken. Otherwise, if the parent row can *not* be
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** found in the parent table:
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**
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** Operation | FK type | Action taken
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** --------------------------------------------------------------------------
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** INSERT immediate Increment the "immediate constraint counter".
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**
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** DELETE immediate Decrement the "immediate constraint counter".
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**
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** INSERT deferred Increment the "deferred constraint counter".
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**
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** DELETE deferred Decrement the "deferred constraint counter".
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**
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** These operations are identified in the comment at the top of this file
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** (fkey.c) as "I.1" and "D.1".
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*/
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static void fkLookupParent(
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Parse *pParse, /* Parse context */
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int iDb, /* Index of database housing pTab */
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Table *pTab, /* Parent table of FK pFKey */
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Index *pIdx, /* Unique index on parent key columns in pTab */
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FKey *pFKey, /* Foreign key constraint */
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int *aiCol, /* Map from parent key columns to child table columns */
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int regData, /* Address of array containing child table row */
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int nIncr, /* Increment constraint counter by this */
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int isIgnore /* If true, pretend pTab contains all NULL values */
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){
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int i; /* Iterator variable */
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Vdbe *v = sqlite3GetVdbe(pParse); /* Vdbe to add code to */
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int iCur = pParse->nTab - 1; /* Cursor number to use */
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int iOk = sqlite3VdbeMakeLabel(v); /* jump here if parent key found */
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/* If nIncr is less than zero, then check at runtime if there are any
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** outstanding constraints to resolve. If there are not, there is no need
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** to check if deleting this row resolves any outstanding violations.
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**
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** Check if any of the key columns in the child table row are NULL. If
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** any are, then the constraint is considered satisfied. No need to
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** search for a matching row in the parent table. */
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if( nIncr<0 ){
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sqlite3VdbeAddOp2(v, OP_FkIfZero, pFKey->isDeferred, iOk);
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}
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for(i=0; i<pFKey->nCol; i++){
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int iReg = aiCol[i] + regData + 1;
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sqlite3VdbeAddOp2(v, OP_IsNull, iReg, iOk);
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}
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if( isIgnore==0 ){
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if( pIdx==0 ){
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/* If pIdx is NULL, then the parent key is the INTEGER PRIMARY KEY
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** column of the parent table (table pTab). */
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int iMustBeInt; /* Address of MustBeInt instruction */
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int regTemp = sqlite3GetTempReg(pParse);
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/* Invoke MustBeInt to coerce the child key value to an integer (i.e.
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** apply the affinity of the parent key). If this fails, then there
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** is no matching parent key. Before using MustBeInt, make a copy of
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** the value. Otherwise, the value inserted into the child key column
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** will have INTEGER affinity applied to it, which may not be correct. */
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sqlite3VdbeAddOp2(v, OP_SCopy, aiCol[0]+1+regData, regTemp);
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iMustBeInt = sqlite3VdbeAddOp2(v, OP_MustBeInt, regTemp, 0);
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/* If the parent table is the same as the child table, and we are about
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** to increment the constraint-counter (i.e. this is an INSERT operation),
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** then check if the row being inserted matches itself. If so, do not
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** increment the constraint-counter. */
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if( pTab==pFKey->pFrom && nIncr==1 ){
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sqlite3VdbeAddOp3(v, OP_Eq, regData, iOk, regTemp);
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}
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sqlite3OpenTable(pParse, iCur, iDb, pTab, OP_OpenRead);
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sqlite3VdbeAddOp3(v, OP_NotExists, iCur, 0, regTemp);
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sqlite3VdbeAddOp2(v, OP_Goto, 0, iOk);
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sqlite3VdbeJumpHere(v, sqlite3VdbeCurrentAddr(v)-2);
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sqlite3VdbeJumpHere(v, iMustBeInt);
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sqlite3ReleaseTempReg(pParse, regTemp);
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}else{
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int nCol = pFKey->nCol;
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int regTemp = sqlite3GetTempRange(pParse, nCol);
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int regRec = sqlite3GetTempReg(pParse);
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KeyInfo *pKey = sqlite3IndexKeyinfo(pParse, pIdx);
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sqlite3VdbeAddOp3(v, OP_OpenRead, iCur, pIdx->tnum, iDb);
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sqlite3VdbeChangeP4(v, -1, (char*)pKey, P4_KEYINFO_HANDOFF);
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for(i=0; i<nCol; i++){
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sqlite3VdbeAddOp2(v, OP_Copy, aiCol[i]+1+regData, regTemp+i);
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}
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/* If the parent table is the same as the child table, and we are about
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** to increment the constraint-counter (i.e. this is an INSERT operation),
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** then check if the row being inserted matches itself. If so, do not
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** increment the constraint-counter.
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**
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** If any of the parent-key values are NULL, then the row cannot match
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** itself. So set JUMPIFNULL to make sure we do the OP_Found if any
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** of the parent-key values are NULL (at this point it is known that
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** none of the child key values are).
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*/
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if( pTab==pFKey->pFrom && nIncr==1 ){
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int iJump = sqlite3VdbeCurrentAddr(v) + nCol + 1;
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for(i=0; i<nCol; i++){
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int iChild = aiCol[i]+1+regData;
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int iParent = pIdx->aiColumn[i]+1+regData;
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assert( aiCol[i]!=pTab->iPKey );
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if( pIdx->aiColumn[i]==pTab->iPKey ){
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/* The parent key is a composite key that includes the IPK column */
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iParent = regData;
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}
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sqlite3VdbeAddOp3(v, OP_Ne, iChild, iJump, iParent);
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sqlite3VdbeChangeP5(v, SQLITE_JUMPIFNULL);
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}
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sqlite3VdbeAddOp2(v, OP_Goto, 0, iOk);
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}
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sqlite3VdbeAddOp3(v, OP_MakeRecord, regTemp, nCol, regRec);
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sqlite3VdbeChangeP4(v, -1, sqlite3IndexAffinityStr(v,pIdx), P4_TRANSIENT);
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sqlite3VdbeAddOp4Int(v, OP_Found, iCur, iOk, regRec, 0);
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sqlite3ReleaseTempReg(pParse, regRec);
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sqlite3ReleaseTempRange(pParse, regTemp, nCol);
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}
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}
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if( !pFKey->isDeferred && !(pParse->db->flags & SQLITE_DeferFKs)
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&& !pParse->pToplevel
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&& !pParse->isMultiWrite
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){
|
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/* Special case: If this is an INSERT statement that will insert exactly
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** one row into the table, raise a constraint immediately instead of
|
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** incrementing a counter. This is necessary as the VM code is being
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** generated for will not open a statement transaction. */
|
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assert( nIncr==1 );
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sqlite3HaltConstraint(pParse, SQLITE_CONSTRAINT_FOREIGNKEY,
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OE_Abort, "foreign key constraint failed", P4_STATIC
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);
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}else{
|
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if( nIncr>0 && pFKey->isDeferred==0 ){
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sqlite3ParseToplevel(pParse)->mayAbort = 1;
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}
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sqlite3VdbeAddOp2(v, OP_FkCounter, pFKey->isDeferred, nIncr);
|
|
}
|
|
|
|
sqlite3VdbeResolveLabel(v, iOk);
|
|
sqlite3VdbeAddOp1(v, OP_Close, iCur);
|
|
}
|
|
|
|
/*
|
|
** This function is called to generate code executed when a row is deleted
|
|
** from the parent table of foreign key constraint pFKey and, if pFKey is
|
|
** deferred, when a row is inserted into the same table. When generating
|
|
** code for an SQL UPDATE operation, this function may be called twice -
|
|
** once to "delete" the old row and once to "insert" the new row.
|
|
**
|
|
** The code generated by this function scans through the rows in the child
|
|
** table that correspond to the parent table row being deleted or inserted.
|
|
** For each child row found, one of the following actions is taken:
|
|
**
|
|
** Operation | FK type | Action taken
|
|
** --------------------------------------------------------------------------
|
|
** DELETE immediate Increment the "immediate constraint counter".
|
|
** Or, if the ON (UPDATE|DELETE) action is RESTRICT,
|
|
** throw a "foreign key constraint failed" exception.
|
|
**
|
|
** INSERT immediate Decrement the "immediate constraint counter".
|
|
**
|
|
** DELETE deferred Increment the "deferred constraint counter".
|
|
** Or, if the ON (UPDATE|DELETE) action is RESTRICT,
|
|
** throw a "foreign key constraint failed" exception.
|
|
**
|
|
** INSERT deferred Decrement the "deferred constraint counter".
|
|
**
|
|
** These operations are identified in the comment at the top of this file
|
|
** (fkey.c) as "I.2" and "D.2".
|
|
*/
|
|
static void fkScanChildren(
|
|
Parse *pParse, /* Parse context */
|
|
SrcList *pSrc, /* SrcList containing the table to scan */
|
|
Table *pTab,
|
|
Index *pIdx, /* Foreign key index */
|
|
FKey *pFKey, /* Foreign key relationship */
|
|
int *aiCol, /* Map from pIdx cols to child table cols */
|
|
int regData, /* Referenced table data starts here */
|
|
int nIncr /* Amount to increment deferred counter by */
|
|
){
|
|
sqlite3 *db = pParse->db; /* Database handle */
|
|
int i; /* Iterator variable */
|
|
Expr *pWhere = 0; /* WHERE clause to scan with */
|
|
NameContext sNameContext; /* Context used to resolve WHERE clause */
|
|
WhereInfo *pWInfo; /* Context used by sqlite3WhereXXX() */
|
|
int iFkIfZero = 0; /* Address of OP_FkIfZero */
|
|
Vdbe *v = sqlite3GetVdbe(pParse);
|
|
|
|
assert( !pIdx || pIdx->pTable==pTab );
|
|
|
|
if( nIncr<0 ){
|
|
iFkIfZero = sqlite3VdbeAddOp2(v, OP_FkIfZero, pFKey->isDeferred, 0);
|
|
}
|
|
|
|
/* Create an Expr object representing an SQL expression like:
|
|
**
|
|
** <parent-key1> = <child-key1> AND <parent-key2> = <child-key2> ...
|
|
**
|
|
** The collation sequence used for the comparison should be that of
|
|
** the parent key columns. The affinity of the parent key column should
|
|
** be applied to each child key value before the comparison takes place.
|
|
*/
|
|
for(i=0; i<pFKey->nCol; i++){
|
|
Expr *pLeft; /* Value from parent table row */
|
|
Expr *pRight; /* Column ref to child table */
|
|
Expr *pEq; /* Expression (pLeft = pRight) */
|
|
int iCol; /* Index of column in child table */
|
|
const char *zCol; /* Name of column in child table */
|
|
|
|
pLeft = sqlite3Expr(db, TK_REGISTER, 0);
|
|
if( pLeft ){
|
|
/* Set the collation sequence and affinity of the LHS of each TK_EQ
|
|
** expression to the parent key column defaults. */
|
|
if( pIdx ){
|
|
Column *pCol;
|
|
const char *zColl;
|
|
iCol = pIdx->aiColumn[i];
|
|
pCol = &pTab->aCol[iCol];
|
|
if( pTab->iPKey==iCol ) iCol = -1;
|
|
pLeft->iTable = regData+iCol+1;
|
|
pLeft->affinity = pCol->affinity;
|
|
zColl = pCol->zColl;
|
|
if( zColl==0 ) zColl = db->pDfltColl->zName;
|
|
pLeft = sqlite3ExprAddCollateString(pParse, pLeft, zColl);
|
|
}else{
|
|
pLeft->iTable = regData;
|
|
pLeft->affinity = SQLITE_AFF_INTEGER;
|
|
}
|
|
}
|
|
iCol = aiCol ? aiCol[i] : pFKey->aCol[0].iFrom;
|
|
assert( iCol>=0 );
|
|
zCol = pFKey->pFrom->aCol[iCol].zName;
|
|
pRight = sqlite3Expr(db, TK_ID, zCol);
|
|
pEq = sqlite3PExpr(pParse, TK_EQ, pLeft, pRight, 0);
|
|
pWhere = sqlite3ExprAnd(db, pWhere, pEq);
|
|
}
|
|
|
|
/* If the child table is the same as the parent table, and this scan
|
|
** is taking place as part of a DELETE operation (operation D.2), omit the
|
|
** row being deleted from the scan by adding ($rowid != rowid) to the WHERE
|
|
** clause, where $rowid is the rowid of the row being deleted. */
|
|
if( pTab==pFKey->pFrom && nIncr>0 ){
|
|
Expr *pEq; /* Expression (pLeft = pRight) */
|
|
Expr *pLeft; /* Value from parent table row */
|
|
Expr *pRight; /* Column ref to child table */
|
|
pLeft = sqlite3Expr(db, TK_REGISTER, 0);
|
|
pRight = sqlite3Expr(db, TK_COLUMN, 0);
|
|
if( pLeft && pRight ){
|
|
pLeft->iTable = regData;
|
|
pLeft->affinity = SQLITE_AFF_INTEGER;
|
|
pRight->iTable = pSrc->a[0].iCursor;
|
|
pRight->iColumn = -1;
|
|
}
|
|
pEq = sqlite3PExpr(pParse, TK_NE, pLeft, pRight, 0);
|
|
pWhere = sqlite3ExprAnd(db, pWhere, pEq);
|
|
}
|
|
|
|
/* Resolve the references in the WHERE clause. */
|
|
memset(&sNameContext, 0, sizeof(NameContext));
|
|
sNameContext.pSrcList = pSrc;
|
|
sNameContext.pParse = pParse;
|
|
sqlite3ResolveExprNames(&sNameContext, pWhere);
|
|
|
|
/* Create VDBE to loop through the entries in pSrc that match the WHERE
|
|
** clause. If the constraint is not deferred, throw an exception for
|
|
** each row found. Otherwise, for deferred constraints, increment the
|
|
** deferred constraint counter by nIncr for each row selected. */
|
|
pWInfo = sqlite3WhereBegin(pParse, pSrc, pWhere, 0, 0, 0, 0);
|
|
if( nIncr>0 && pFKey->isDeferred==0 ){
|
|
sqlite3ParseToplevel(pParse)->mayAbort = 1;
|
|
}
|
|
sqlite3VdbeAddOp2(v, OP_FkCounter, pFKey->isDeferred, nIncr);
|
|
if( pWInfo ){
|
|
sqlite3WhereEnd(pWInfo);
|
|
}
|
|
|
|
/* Clean up the WHERE clause constructed above. */
|
|
sqlite3ExprDelete(db, pWhere);
|
|
if( iFkIfZero ){
|
|
sqlite3VdbeJumpHere(v, iFkIfZero);
|
|
}
|
|
}
|
|
|
|
/*
|
|
** This function returns a pointer to the head of a linked list of FK
|
|
** constraints for which table pTab is the parent table. For example,
|
|
** given the following schema:
|
|
**
|
|
** CREATE TABLE t1(a PRIMARY KEY);
|
|
** CREATE TABLE t2(b REFERENCES t1(a);
|
|
**
|
|
** Calling this function with table "t1" as an argument returns a pointer
|
|
** to the FKey structure representing the foreign key constraint on table
|
|
** "t2". Calling this function with "t2" as the argument would return a
|
|
** NULL pointer (as there are no FK constraints for which t2 is the parent
|
|
** table).
|
|
*/
|
|
FKey *sqlite3FkReferences(Table *pTab){
|
|
int nName = sqlite3Strlen30(pTab->zName);
|
|
return (FKey *)sqlite3HashFind(&pTab->pSchema->fkeyHash, pTab->zName, nName);
|
|
}
|
|
|
|
/*
|
|
** The second argument is a Trigger structure allocated by the
|
|
** fkActionTrigger() routine. This function deletes the Trigger structure
|
|
** and all of its sub-components.
|
|
**
|
|
** The Trigger structure or any of its sub-components may be allocated from
|
|
** the lookaside buffer belonging to database handle dbMem.
|
|
*/
|
|
static void fkTriggerDelete(sqlite3 *dbMem, Trigger *p){
|
|
if( p ){
|
|
TriggerStep *pStep = p->step_list;
|
|
sqlite3ExprDelete(dbMem, pStep->pWhere);
|
|
sqlite3ExprListDelete(dbMem, pStep->pExprList);
|
|
sqlite3SelectDelete(dbMem, pStep->pSelect);
|
|
sqlite3ExprDelete(dbMem, p->pWhen);
|
|
sqlite3DbFree(dbMem, p);
|
|
}
|
|
}
|
|
|
|
/*
|
|
** This function is called to generate code that runs when table pTab is
|
|
** being dropped from the database. The SrcList passed as the second argument
|
|
** to this function contains a single entry guaranteed to resolve to
|
|
** table pTab.
|
|
**
|
|
** Normally, no code is required. However, if either
|
|
**
|
|
** (a) The table is the parent table of a FK constraint, or
|
|
** (b) The table is the child table of a deferred FK constraint and it is
|
|
** determined at runtime that there are outstanding deferred FK
|
|
** constraint violations in the database,
|
|
**
|
|
** then the equivalent of "DELETE FROM <tbl>" is executed before dropping
|
|
** the table from the database. Triggers are disabled while running this
|
|
** DELETE, but foreign key actions are not.
|
|
*/
|
|
void sqlite3FkDropTable(Parse *pParse, SrcList *pName, Table *pTab){
|
|
sqlite3 *db = pParse->db;
|
|
if( (db->flags&SQLITE_ForeignKeys) && !IsVirtual(pTab) && !pTab->pSelect ){
|
|
int iSkip = 0;
|
|
Vdbe *v = sqlite3GetVdbe(pParse);
|
|
|
|
assert( v ); /* VDBE has already been allocated */
|
|
if( sqlite3FkReferences(pTab)==0 ){
|
|
/* Search for a deferred foreign key constraint for which this table
|
|
** is the child table. If one cannot be found, return without
|
|
** generating any VDBE code. If one can be found, then jump over
|
|
** the entire DELETE if there are no outstanding deferred constraints
|
|
** when this statement is run. */
|
|
FKey *p;
|
|
for(p=pTab->pFKey; p; p=p->pNextFrom){
|
|
if( p->isDeferred || (db->flags & SQLITE_DeferFKs) ) break;
|
|
}
|
|
if( !p ) return;
|
|
iSkip = sqlite3VdbeMakeLabel(v);
|
|
sqlite3VdbeAddOp2(v, OP_FkIfZero, 1, iSkip);
|
|
}
|
|
|
|
pParse->disableTriggers = 1;
|
|
sqlite3DeleteFrom(pParse, sqlite3SrcListDup(db, pName, 0), 0);
|
|
pParse->disableTriggers = 0;
|
|
|
|
/* If the DELETE has generated immediate foreign key constraint
|
|
** violations, halt the VDBE and return an error at this point, before
|
|
** any modifications to the schema are made. This is because statement
|
|
** transactions are not able to rollback schema changes.
|
|
**
|
|
** If the SQLITE_DeferFKs flag is set, then this is not required, as
|
|
** the statement transaction will not be rolled back even if FK
|
|
** constraints are violated.
|
|
*/
|
|
if( (db->flags & SQLITE_DeferFKs)==0 ){
|
|
sqlite3VdbeAddOp2(v, OP_FkIfZero, 0, sqlite3VdbeCurrentAddr(v)+2);
|
|
sqlite3HaltConstraint(pParse, SQLITE_CONSTRAINT_FOREIGNKEY,
|
|
OE_Abort, "foreign key constraint failed", P4_STATIC
|
|
);
|
|
}
|
|
|
|
if( iSkip ){
|
|
sqlite3VdbeResolveLabel(v, iSkip);
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
/*
|
|
** The second argument points to an FKey object representing a foreign key
|
|
** for which pTab is the child table. An UPDATE statement against pTab
|
|
** is currently being processed. For each column of the table that is
|
|
** actually updated, the corresponding element in the aChange[] array
|
|
** is zero or greater (if a column is unmodified the corresponding element
|
|
** is set to -1). If the rowid column is modified by the UPDATE statement
|
|
** the bChngRowid argument is non-zero.
|
|
**
|
|
** This function returns true if any of the columns that are part of the
|
|
** child key for FK constraint *p are modified.
|
|
*/
|
|
static int fkChildIsModified(
|
|
Table *pTab, /* Table being updated */
|
|
FKey *p, /* Foreign key for which pTab is the child */
|
|
int *aChange, /* Array indicating modified columns */
|
|
int bChngRowid /* True if rowid is modified by this update */
|
|
){
|
|
int i;
|
|
for(i=0; i<p->nCol; i++){
|
|
int iChildKey = p->aCol[i].iFrom;
|
|
if( aChange[iChildKey]>=0 ) return 1;
|
|
if( iChildKey==pTab->iPKey && bChngRowid ) return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
** The second argument points to an FKey object representing a foreign key
|
|
** for which pTab is the parent table. An UPDATE statement against pTab
|
|
** is currently being processed. For each column of the table that is
|
|
** actually updated, the corresponding element in the aChange[] array
|
|
** is zero or greater (if a column is unmodified the corresponding element
|
|
** is set to -1). If the rowid column is modified by the UPDATE statement
|
|
** the bChngRowid argument is non-zero.
|
|
**
|
|
** This function returns true if any of the columns that are part of the
|
|
** parent key for FK constraint *p are modified.
|
|
*/
|
|
static int fkParentIsModified(
|
|
Table *pTab,
|
|
FKey *p,
|
|
int *aChange,
|
|
int bChngRowid
|
|
){
|
|
int i;
|
|
for(i=0; i<p->nCol; i++){
|
|
char *zKey = p->aCol[i].zCol;
|
|
int iKey;
|
|
for(iKey=0; iKey<pTab->nCol; iKey++){
|
|
if( aChange[iKey]>=0 || (iKey==pTab->iPKey && bChngRowid) ){
|
|
Column *pCol = &pTab->aCol[iKey];
|
|
if( zKey ){
|
|
if( 0==sqlite3StrICmp(pCol->zName, zKey) ) return 1;
|
|
}else if( pCol->colFlags & COLFLAG_PRIMKEY ){
|
|
return 1;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
** This function is called when inserting, deleting or updating a row of
|
|
** table pTab to generate VDBE code to perform foreign key constraint
|
|
** processing for the operation.
|
|
**
|
|
** For a DELETE operation, parameter regOld is passed the index of the
|
|
** first register in an array of (pTab->nCol+1) registers containing the
|
|
** rowid of the row being deleted, followed by each of the column values
|
|
** of the row being deleted, from left to right. Parameter regNew is passed
|
|
** zero in this case.
|
|
**
|
|
** For an INSERT operation, regOld is passed zero and regNew is passed the
|
|
** first register of an array of (pTab->nCol+1) registers containing the new
|
|
** row data.
|
|
**
|
|
** For an UPDATE operation, this function is called twice. Once before
|
|
** the original record is deleted from the table using the calling convention
|
|
** described for DELETE. Then again after the original record is deleted
|
|
** but before the new record is inserted using the INSERT convention.
|
|
*/
|
|
void sqlite3FkCheck(
|
|
Parse *pParse, /* Parse context */
|
|
Table *pTab, /* Row is being deleted from this table */
|
|
int regOld, /* Previous row data is stored here */
|
|
int regNew, /* New row data is stored here */
|
|
int *aChange, /* Array indicating UPDATEd columns (or 0) */
|
|
int bChngRowid /* True if rowid is UPDATEd */
|
|
){
|
|
sqlite3 *db = pParse->db; /* Database handle */
|
|
FKey *pFKey; /* Used to iterate through FKs */
|
|
int iDb; /* Index of database containing pTab */
|
|
const char *zDb; /* Name of database containing pTab */
|
|
int isIgnoreErrors = pParse->disableTriggers;
|
|
|
|
/* Exactly one of regOld and regNew should be non-zero. */
|
|
assert( (regOld==0)!=(regNew==0) );
|
|
|
|
/* If foreign-keys are disabled, this function is a no-op. */
|
|
if( (db->flags&SQLITE_ForeignKeys)==0 ) return;
|
|
|
|
iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
|
|
zDb = db->aDb[iDb].zName;
|
|
|
|
/* Loop through all the foreign key constraints for which pTab is the
|
|
** child table (the table that the foreign key definition is part of). */
|
|
for(pFKey=pTab->pFKey; pFKey; pFKey=pFKey->pNextFrom){
|
|
Table *pTo; /* Parent table of foreign key pFKey */
|
|
Index *pIdx = 0; /* Index on key columns in pTo */
|
|
int *aiFree = 0;
|
|
int *aiCol;
|
|
int iCol;
|
|
int i;
|
|
int isIgnore = 0;
|
|
|
|
if( aChange
|
|
&& sqlite3_stricmp(pTab->zName, pFKey->zTo)!=0
|
|
&& fkChildIsModified(pTab, pFKey, aChange, bChngRowid)==0
|
|
){
|
|
continue;
|
|
}
|
|
|
|
/* Find the parent table of this foreign key. Also find a unique index
|
|
** on the parent key columns in the parent table. If either of these
|
|
** schema items cannot be located, set an error in pParse and return
|
|
** early. */
|
|
if( pParse->disableTriggers ){
|
|
pTo = sqlite3FindTable(db, pFKey->zTo, zDb);
|
|
}else{
|
|
pTo = sqlite3LocateTable(pParse, 0, pFKey->zTo, zDb);
|
|
}
|
|
if( !pTo || sqlite3FkLocateIndex(pParse, pTo, pFKey, &pIdx, &aiFree) ){
|
|
assert( isIgnoreErrors==0 || (regOld!=0 && regNew==0) );
|
|
if( !isIgnoreErrors || db->mallocFailed ) return;
|
|
if( pTo==0 ){
|
|
/* If isIgnoreErrors is true, then a table is being dropped. In this
|
|
** case SQLite runs a "DELETE FROM xxx" on the table being dropped
|
|
** before actually dropping it in order to check FK constraints.
|
|
** If the parent table of an FK constraint on the current table is
|
|
** missing, behave as if it is empty. i.e. decrement the relevant
|
|
** FK counter for each row of the current table with non-NULL keys.
|
|
*/
|
|
Vdbe *v = sqlite3GetVdbe(pParse);
|
|
int iJump = sqlite3VdbeCurrentAddr(v) + pFKey->nCol + 1;
|
|
for(i=0; i<pFKey->nCol; i++){
|
|
int iReg = pFKey->aCol[i].iFrom + regOld + 1;
|
|
sqlite3VdbeAddOp2(v, OP_IsNull, iReg, iJump);
|
|
}
|
|
sqlite3VdbeAddOp2(v, OP_FkCounter, pFKey->isDeferred, -1);
|
|
}
|
|
continue;
|
|
}
|
|
assert( pFKey->nCol==1 || (aiFree && pIdx) );
|
|
|
|
if( aiFree ){
|
|
aiCol = aiFree;
|
|
}else{
|
|
iCol = pFKey->aCol[0].iFrom;
|
|
aiCol = &iCol;
|
|
}
|
|
for(i=0; i<pFKey->nCol; i++){
|
|
if( aiCol[i]==pTab->iPKey ){
|
|
aiCol[i] = -1;
|
|
}
|
|
#ifndef SQLITE_OMIT_AUTHORIZATION
|
|
/* Request permission to read the parent key columns. If the
|
|
** authorization callback returns SQLITE_IGNORE, behave as if any
|
|
** values read from the parent table are NULL. */
|
|
if( db->xAuth ){
|
|
int rcauth;
|
|
char *zCol = pTo->aCol[pIdx ? pIdx->aiColumn[i] : pTo->iPKey].zName;
|
|
rcauth = sqlite3AuthReadCol(pParse, pTo->zName, zCol, iDb);
|
|
isIgnore = (rcauth==SQLITE_IGNORE);
|
|
}
|
|
#endif
|
|
}
|
|
|
|
/* Take a shared-cache advisory read-lock on the parent table. Allocate
|
|
** a cursor to use to search the unique index on the parent key columns
|
|
** in the parent table. */
|
|
sqlite3TableLock(pParse, iDb, pTo->tnum, 0, pTo->zName);
|
|
pParse->nTab++;
|
|
|
|
if( regOld!=0 ){
|
|
/* A row is being removed from the child table. Search for the parent.
|
|
** If the parent does not exist, removing the child row resolves an
|
|
** outstanding foreign key constraint violation. */
|
|
fkLookupParent(pParse, iDb, pTo, pIdx, pFKey, aiCol, regOld, -1,isIgnore);
|
|
}
|
|
if( regNew!=0 ){
|
|
/* A row is being added to the child table. If a parent row cannot
|
|
** be found, adding the child row has violated the FK constraint. */
|
|
fkLookupParent(pParse, iDb, pTo, pIdx, pFKey, aiCol, regNew, +1,isIgnore);
|
|
}
|
|
|
|
sqlite3DbFree(db, aiFree);
|
|
}
|
|
|
|
/* Loop through all the foreign key constraints that refer to this table */
|
|
for(pFKey = sqlite3FkReferences(pTab); pFKey; pFKey=pFKey->pNextTo){
|
|
Index *pIdx = 0; /* Foreign key index for pFKey */
|
|
SrcList *pSrc;
|
|
int *aiCol = 0;
|
|
|
|
if( aChange && fkParentIsModified(pTab, pFKey, aChange, bChngRowid)==0 ){
|
|
continue;
|
|
}
|
|
|
|
if( !pFKey->isDeferred && !(db->flags & SQLITE_DeferFKs)
|
|
&& !pParse->pToplevel && !pParse->isMultiWrite
|
|
){
|
|
assert( regOld==0 && regNew!=0 );
|
|
/* Inserting a single row into a parent table cannot cause an immediate
|
|
** foreign key violation. So do nothing in this case. */
|
|
continue;
|
|
}
|
|
|
|
if( sqlite3FkLocateIndex(pParse, pTab, pFKey, &pIdx, &aiCol) ){
|
|
if( !isIgnoreErrors || db->mallocFailed ) return;
|
|
continue;
|
|
}
|
|
assert( aiCol || pFKey->nCol==1 );
|
|
|
|
/* Create a SrcList structure containing a single table (the table
|
|
** the foreign key that refers to this table is attached to). This
|
|
** is required for the sqlite3WhereXXX() interface. */
|
|
pSrc = sqlite3SrcListAppend(db, 0, 0, 0);
|
|
if( pSrc ){
|
|
struct SrcList_item *pItem = pSrc->a;
|
|
pItem->pTab = pFKey->pFrom;
|
|
pItem->zName = pFKey->pFrom->zName;
|
|
pItem->pTab->nRef++;
|
|
pItem->iCursor = pParse->nTab++;
|
|
|
|
if( regNew!=0 ){
|
|
fkScanChildren(pParse, pSrc, pTab, pIdx, pFKey, aiCol, regNew, -1);
|
|
}
|
|
if( regOld!=0 ){
|
|
/* If there is a RESTRICT action configured for the current operation
|
|
** on the parent table of this FK, then throw an exception
|
|
** immediately if the FK constraint is violated, even if this is a
|
|
** deferred trigger. That's what RESTRICT means. To defer checking
|
|
** the constraint, the FK should specify NO ACTION (represented
|
|
** using OE_None). NO ACTION is the default. */
|
|
fkScanChildren(pParse, pSrc, pTab, pIdx, pFKey, aiCol, regOld, 1);
|
|
}
|
|
pItem->zName = 0;
|
|
sqlite3SrcListDelete(db, pSrc);
|
|
}
|
|
sqlite3DbFree(db, aiCol);
|
|
}
|
|
}
|
|
|
|
#define COLUMN_MASK(x) (((x)>31) ? 0xffffffff : ((u32)1<<(x)))
|
|
|
|
/*
|
|
** This function is called before generating code to update or delete a
|
|
** row contained in table pTab.
|
|
*/
|
|
u32 sqlite3FkOldmask(
|
|
Parse *pParse, /* Parse context */
|
|
Table *pTab /* Table being modified */
|
|
){
|
|
u32 mask = 0;
|
|
if( pParse->db->flags&SQLITE_ForeignKeys ){
|
|
FKey *p;
|
|
int i;
|
|
for(p=pTab->pFKey; p; p=p->pNextFrom){
|
|
for(i=0; i<p->nCol; i++) mask |= COLUMN_MASK(p->aCol[i].iFrom);
|
|
}
|
|
for(p=sqlite3FkReferences(pTab); p; p=p->pNextTo){
|
|
Index *pIdx = 0;
|
|
sqlite3FkLocateIndex(pParse, pTab, p, &pIdx, 0);
|
|
if( pIdx ){
|
|
for(i=0; i<pIdx->nColumn; i++) mask |= COLUMN_MASK(pIdx->aiColumn[i]);
|
|
}
|
|
}
|
|
}
|
|
return mask;
|
|
}
|
|
|
|
|
|
/*
|
|
** This function is called before generating code to update or delete a
|
|
** row contained in table pTab. If the operation is a DELETE, then
|
|
** parameter aChange is passed a NULL value. For an UPDATE, aChange points
|
|
** to an array of size N, where N is the number of columns in table pTab.
|
|
** If the i'th column is not modified by the UPDATE, then the corresponding
|
|
** entry in the aChange[] array is set to -1. If the column is modified,
|
|
** the value is 0 or greater. Parameter chngRowid is set to true if the
|
|
** UPDATE statement modifies the rowid fields of the table.
|
|
**
|
|
** If any foreign key processing will be required, this function returns
|
|
** true. If there is no foreign key related processing, this function
|
|
** returns false.
|
|
*/
|
|
int sqlite3FkRequired(
|
|
Parse *pParse, /* Parse context */
|
|
Table *pTab, /* Table being modified */
|
|
int *aChange, /* Non-NULL for UPDATE operations */
|
|
int chngRowid /* True for UPDATE that affects rowid */
|
|
){
|
|
if( pParse->db->flags&SQLITE_ForeignKeys ){
|
|
if( !aChange ){
|
|
/* A DELETE operation. Foreign key processing is required if the
|
|
** table in question is either the child or parent table for any
|
|
** foreign key constraint. */
|
|
return (sqlite3FkReferences(pTab) || pTab->pFKey);
|
|
}else{
|
|
/* This is an UPDATE. Foreign key processing is only required if the
|
|
** operation modifies one or more child or parent key columns. */
|
|
FKey *p;
|
|
|
|
/* Check if any child key columns are being modified. */
|
|
for(p=pTab->pFKey; p; p=p->pNextFrom){
|
|
if( fkChildIsModified(pTab, p, aChange, chngRowid) ) return 1;
|
|
}
|
|
|
|
/* Check if any parent key columns are being modified. */
|
|
for(p=sqlite3FkReferences(pTab); p; p=p->pNextTo){
|
|
if( fkParentIsModified(pTab, p, aChange, chngRowid) ) return 1;
|
|
}
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
** This function is called when an UPDATE or DELETE operation is being
|
|
** compiled on table pTab, which is the parent table of foreign-key pFKey.
|
|
** If the current operation is an UPDATE, then the pChanges parameter is
|
|
** passed a pointer to the list of columns being modified. If it is a
|
|
** DELETE, pChanges is passed a NULL pointer.
|
|
**
|
|
** It returns a pointer to a Trigger structure containing a trigger
|
|
** equivalent to the ON UPDATE or ON DELETE action specified by pFKey.
|
|
** If the action is "NO ACTION" or "RESTRICT", then a NULL pointer is
|
|
** returned (these actions require no special handling by the triggers
|
|
** sub-system, code for them is created by fkScanChildren()).
|
|
**
|
|
** For example, if pFKey is the foreign key and pTab is table "p" in
|
|
** the following schema:
|
|
**
|
|
** CREATE TABLE p(pk PRIMARY KEY);
|
|
** CREATE TABLE c(ck REFERENCES p ON DELETE CASCADE);
|
|
**
|
|
** then the returned trigger structure is equivalent to:
|
|
**
|
|
** CREATE TRIGGER ... DELETE ON p BEGIN
|
|
** DELETE FROM c WHERE ck = old.pk;
|
|
** END;
|
|
**
|
|
** The returned pointer is cached as part of the foreign key object. It
|
|
** is eventually freed along with the rest of the foreign key object by
|
|
** sqlite3FkDelete().
|
|
*/
|
|
static Trigger *fkActionTrigger(
|
|
Parse *pParse, /* Parse context */
|
|
Table *pTab, /* Table being updated or deleted from */
|
|
FKey *pFKey, /* Foreign key to get action for */
|
|
ExprList *pChanges /* Change-list for UPDATE, NULL for DELETE */
|
|
){
|
|
sqlite3 *db = pParse->db; /* Database handle */
|
|
int action; /* One of OE_None, OE_Cascade etc. */
|
|
Trigger *pTrigger; /* Trigger definition to return */
|
|
int iAction = (pChanges!=0); /* 1 for UPDATE, 0 for DELETE */
|
|
|
|
action = pFKey->aAction[iAction];
|
|
pTrigger = pFKey->apTrigger[iAction];
|
|
|
|
if( action!=OE_None && !pTrigger ){
|
|
u8 enableLookaside; /* Copy of db->lookaside.bEnabled */
|
|
char const *zFrom; /* Name of child table */
|
|
int nFrom; /* Length in bytes of zFrom */
|
|
Index *pIdx = 0; /* Parent key index for this FK */
|
|
int *aiCol = 0; /* child table cols -> parent key cols */
|
|
TriggerStep *pStep = 0; /* First (only) step of trigger program */
|
|
Expr *pWhere = 0; /* WHERE clause of trigger step */
|
|
ExprList *pList = 0; /* Changes list if ON UPDATE CASCADE */
|
|
Select *pSelect = 0; /* If RESTRICT, "SELECT RAISE(...)" */
|
|
int i; /* Iterator variable */
|
|
Expr *pWhen = 0; /* WHEN clause for the trigger */
|
|
|
|
if( sqlite3FkLocateIndex(pParse, pTab, pFKey, &pIdx, &aiCol) ) return 0;
|
|
assert( aiCol || pFKey->nCol==1 );
|
|
|
|
for(i=0; i<pFKey->nCol; i++){
|
|
Token tOld = { "old", 3 }; /* Literal "old" token */
|
|
Token tNew = { "new", 3 }; /* Literal "new" token */
|
|
Token tFromCol; /* Name of column in child table */
|
|
Token tToCol; /* Name of column in parent table */
|
|
int iFromCol; /* Idx of column in child table */
|
|
Expr *pEq; /* tFromCol = OLD.tToCol */
|
|
|
|
iFromCol = aiCol ? aiCol[i] : pFKey->aCol[0].iFrom;
|
|
assert( iFromCol>=0 );
|
|
tToCol.z = pIdx ? pTab->aCol[pIdx->aiColumn[i]].zName : "oid";
|
|
tFromCol.z = pFKey->pFrom->aCol[iFromCol].zName;
|
|
|
|
tToCol.n = sqlite3Strlen30(tToCol.z);
|
|
tFromCol.n = sqlite3Strlen30(tFromCol.z);
|
|
|
|
/* Create the expression "OLD.zToCol = zFromCol". It is important
|
|
** that the "OLD.zToCol" term is on the LHS of the = operator, so
|
|
** that the affinity and collation sequence associated with the
|
|
** parent table are used for the comparison. */
|
|
pEq = sqlite3PExpr(pParse, TK_EQ,
|
|
sqlite3PExpr(pParse, TK_DOT,
|
|
sqlite3PExpr(pParse, TK_ID, 0, 0, &tOld),
|
|
sqlite3PExpr(pParse, TK_ID, 0, 0, &tToCol)
|
|
, 0),
|
|
sqlite3PExpr(pParse, TK_ID, 0, 0, &tFromCol)
|
|
, 0);
|
|
pWhere = sqlite3ExprAnd(db, pWhere, pEq);
|
|
|
|
/* For ON UPDATE, construct the next term of the WHEN clause.
|
|
** The final WHEN clause will be like this:
|
|
**
|
|
** WHEN NOT(old.col1 IS new.col1 AND ... AND old.colN IS new.colN)
|
|
*/
|
|
if( pChanges ){
|
|
pEq = sqlite3PExpr(pParse, TK_IS,
|
|
sqlite3PExpr(pParse, TK_DOT,
|
|
sqlite3PExpr(pParse, TK_ID, 0, 0, &tOld),
|
|
sqlite3PExpr(pParse, TK_ID, 0, 0, &tToCol),
|
|
0),
|
|
sqlite3PExpr(pParse, TK_DOT,
|
|
sqlite3PExpr(pParse, TK_ID, 0, 0, &tNew),
|
|
sqlite3PExpr(pParse, TK_ID, 0, 0, &tToCol),
|
|
0),
|
|
0);
|
|
pWhen = sqlite3ExprAnd(db, pWhen, pEq);
|
|
}
|
|
|
|
if( action!=OE_Restrict && (action!=OE_Cascade || pChanges) ){
|
|
Expr *pNew;
|
|
if( action==OE_Cascade ){
|
|
pNew = sqlite3PExpr(pParse, TK_DOT,
|
|
sqlite3PExpr(pParse, TK_ID, 0, 0, &tNew),
|
|
sqlite3PExpr(pParse, TK_ID, 0, 0, &tToCol)
|
|
, 0);
|
|
}else if( action==OE_SetDflt ){
|
|
Expr *pDflt = pFKey->pFrom->aCol[iFromCol].pDflt;
|
|
if( pDflt ){
|
|
pNew = sqlite3ExprDup(db, pDflt, 0);
|
|
}else{
|
|
pNew = sqlite3PExpr(pParse, TK_NULL, 0, 0, 0);
|
|
}
|
|
}else{
|
|
pNew = sqlite3PExpr(pParse, TK_NULL, 0, 0, 0);
|
|
}
|
|
pList = sqlite3ExprListAppend(pParse, pList, pNew);
|
|
sqlite3ExprListSetName(pParse, pList, &tFromCol, 0);
|
|
}
|
|
}
|
|
sqlite3DbFree(db, aiCol);
|
|
|
|
zFrom = pFKey->pFrom->zName;
|
|
nFrom = sqlite3Strlen30(zFrom);
|
|
|
|
if( action==OE_Restrict ){
|
|
Token tFrom;
|
|
Expr *pRaise;
|
|
|
|
tFrom.z = zFrom;
|
|
tFrom.n = nFrom;
|
|
pRaise = sqlite3Expr(db, TK_RAISE, "foreign key constraint failed");
|
|
if( pRaise ){
|
|
pRaise->affinity = OE_Abort;
|
|
}
|
|
pSelect = sqlite3SelectNew(pParse,
|
|
sqlite3ExprListAppend(pParse, 0, pRaise),
|
|
sqlite3SrcListAppend(db, 0, &tFrom, 0),
|
|
pWhere,
|
|
0, 0, 0, 0, 0, 0
|
|
);
|
|
pWhere = 0;
|
|
}
|
|
|
|
/* Disable lookaside memory allocation */
|
|
enableLookaside = db->lookaside.bEnabled;
|
|
db->lookaside.bEnabled = 0;
|
|
|
|
pTrigger = (Trigger *)sqlite3DbMallocZero(db,
|
|
sizeof(Trigger) + /* struct Trigger */
|
|
sizeof(TriggerStep) + /* Single step in trigger program */
|
|
nFrom + 1 /* Space for pStep->target.z */
|
|
);
|
|
if( pTrigger ){
|
|
pStep = pTrigger->step_list = (TriggerStep *)&pTrigger[1];
|
|
pStep->target.z = (char *)&pStep[1];
|
|
pStep->target.n = nFrom;
|
|
memcpy((char *)pStep->target.z, zFrom, nFrom);
|
|
|
|
pStep->pWhere = sqlite3ExprDup(db, pWhere, EXPRDUP_REDUCE);
|
|
pStep->pExprList = sqlite3ExprListDup(db, pList, EXPRDUP_REDUCE);
|
|
pStep->pSelect = sqlite3SelectDup(db, pSelect, EXPRDUP_REDUCE);
|
|
if( pWhen ){
|
|
pWhen = sqlite3PExpr(pParse, TK_NOT, pWhen, 0, 0);
|
|
pTrigger->pWhen = sqlite3ExprDup(db, pWhen, EXPRDUP_REDUCE);
|
|
}
|
|
}
|
|
|
|
/* Re-enable the lookaside buffer, if it was disabled earlier. */
|
|
db->lookaside.bEnabled = enableLookaside;
|
|
|
|
sqlite3ExprDelete(db, pWhere);
|
|
sqlite3ExprDelete(db, pWhen);
|
|
sqlite3ExprListDelete(db, pList);
|
|
sqlite3SelectDelete(db, pSelect);
|
|
if( db->mallocFailed==1 ){
|
|
fkTriggerDelete(db, pTrigger);
|
|
return 0;
|
|
}
|
|
assert( pStep!=0 );
|
|
|
|
switch( action ){
|
|
case OE_Restrict:
|
|
pStep->op = TK_SELECT;
|
|
break;
|
|
case OE_Cascade:
|
|
if( !pChanges ){
|
|
pStep->op = TK_DELETE;
|
|
break;
|
|
}
|
|
default:
|
|
pStep->op = TK_UPDATE;
|
|
}
|
|
pStep->pTrig = pTrigger;
|
|
pTrigger->pSchema = pTab->pSchema;
|
|
pTrigger->pTabSchema = pTab->pSchema;
|
|
pFKey->apTrigger[iAction] = pTrigger;
|
|
pTrigger->op = (pChanges ? TK_UPDATE : TK_DELETE);
|
|
}
|
|
|
|
return pTrigger;
|
|
}
|
|
|
|
/*
|
|
** This function is called when deleting or updating a row to implement
|
|
** any required CASCADE, SET NULL or SET DEFAULT actions.
|
|
*/
|
|
void sqlite3FkActions(
|
|
Parse *pParse, /* Parse context */
|
|
Table *pTab, /* Table being updated or deleted from */
|
|
ExprList *pChanges, /* Change-list for UPDATE, NULL for DELETE */
|
|
int regOld, /* Address of array containing old row */
|
|
int *aChange, /* Array indicating UPDATEd columns (or 0) */
|
|
int bChngRowid /* True if rowid is UPDATEd */
|
|
){
|
|
/* If foreign-key support is enabled, iterate through all FKs that
|
|
** refer to table pTab. If there is an action associated with the FK
|
|
** for this operation (either update or delete), invoke the associated
|
|
** trigger sub-program. */
|
|
if( pParse->db->flags&SQLITE_ForeignKeys ){
|
|
FKey *pFKey; /* Iterator variable */
|
|
for(pFKey = sqlite3FkReferences(pTab); pFKey; pFKey=pFKey->pNextTo){
|
|
if( aChange==0 || fkParentIsModified(pTab, pFKey, aChange, bChngRowid) ){
|
|
Trigger *pAct = fkActionTrigger(pParse, pTab, pFKey, pChanges);
|
|
if( pAct ){
|
|
sqlite3CodeRowTriggerDirect(pParse, pAct, pTab, regOld, OE_Abort, 0);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
#endif /* ifndef SQLITE_OMIT_TRIGGER */
|
|
|
|
/*
|
|
** Free all memory associated with foreign key definitions attached to
|
|
** table pTab. Remove the deleted foreign keys from the Schema.fkeyHash
|
|
** hash table.
|
|
*/
|
|
void sqlite3FkDelete(sqlite3 *db, Table *pTab){
|
|
FKey *pFKey; /* Iterator variable */
|
|
FKey *pNext; /* Copy of pFKey->pNextFrom */
|
|
|
|
assert( db==0 || sqlite3SchemaMutexHeld(db, 0, pTab->pSchema) );
|
|
for(pFKey=pTab->pFKey; pFKey; pFKey=pNext){
|
|
|
|
/* Remove the FK from the fkeyHash hash table. */
|
|
if( !db || db->pnBytesFreed==0 ){
|
|
if( pFKey->pPrevTo ){
|
|
pFKey->pPrevTo->pNextTo = pFKey->pNextTo;
|
|
}else{
|
|
void *p = (void *)pFKey->pNextTo;
|
|
const char *z = (p ? pFKey->pNextTo->zTo : pFKey->zTo);
|
|
sqlite3HashInsert(&pTab->pSchema->fkeyHash, z, sqlite3Strlen30(z), p);
|
|
}
|
|
if( pFKey->pNextTo ){
|
|
pFKey->pNextTo->pPrevTo = pFKey->pPrevTo;
|
|
}
|
|
}
|
|
|
|
/* EV: R-30323-21917 Each foreign key constraint in SQLite is
|
|
** classified as either immediate or deferred.
|
|
*/
|
|
assert( pFKey->isDeferred==0 || pFKey->isDeferred==1 );
|
|
|
|
/* Delete any triggers created to implement actions for this FK. */
|
|
#ifndef SQLITE_OMIT_TRIGGER
|
|
fkTriggerDelete(db, pFKey->apTrigger[0]);
|
|
fkTriggerDelete(db, pFKey->apTrigger[1]);
|
|
#endif
|
|
|
|
pNext = pFKey->pNextFrom;
|
|
sqlite3DbFree(db, pFKey);
|
|
}
|
|
}
|
|
#endif /* ifndef SQLITE_OMIT_FOREIGN_KEY */
|