diff options
author | Hans-Christoph Steiner <hans@eds.org> | 2012-03-30 20:42:12 -0400 |
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committer | Hans-Christoph Steiner <hans@eds.org> | 2012-03-30 20:42:12 -0400 |
commit | 7bb481fda9ecb134804b49c2ce77ca28f7eea583 (patch) | |
tree | 31b520b9914d3e2453968abe375f2c102772c3dc /src/fkey.c |
Imported Upstream version 2.0.3
Diffstat (limited to 'src/fkey.c')
-rw-r--r-- | src/fkey.c | 1219 |
1 files changed, 1219 insertions, 0 deletions
diff --git a/src/fkey.c b/src/fkey.c new file mode 100644 index 0000000..82e4cdc --- /dev/null +++ b/src/fkey.c @@ -0,0 +1,1219 @@ +/* +** +** The author disclaims copyright to this source code. In place of +** a legal notice, here is a blessing: +** +** May you do good and not evil. +** May you find forgiveness for yourself and forgive others. +** May you share freely, never taking more than you give. +** +************************************************************************* +** This file contains code used by the compiler to add foreign key +** support to compiled SQL statements. +*/ +#include "sqliteInt.h" + +#ifndef SQLITE_OMIT_FOREIGN_KEY +#ifndef SQLITE_OMIT_TRIGGER + +/* +** Deferred and Immediate FKs +** -------------------------- +** +** Foreign keys in SQLite come in two flavours: deferred and immediate. +** If an immediate foreign key constraint is violated, SQLITE_CONSTRAINT +** is returned and the current statement transaction rolled back. If a +** deferred foreign key constraint is violated, no action is taken +** immediately. However if the application attempts to commit the +** transaction before fixing the constraint violation, the attempt fails. +** +** Deferred constraints are implemented using a simple counter associated +** with the database handle. The counter is set to zero each time a +** database transaction is opened. Each time a statement is executed +** that causes a foreign key violation, the counter is incremented. Each +** time a statement is executed that removes an existing violation from +** the database, the counter is decremented. When the transaction is +** committed, the commit fails if the current value of the counter is +** greater than zero. This scheme has two big drawbacks: +** +** * When a commit fails due to a deferred foreign key constraint, +** there is no way to tell which foreign constraint is not satisfied, +** or which row it is not satisfied for. +** +** * If the database contains foreign key violations when the +** transaction is opened, this may cause the mechanism to malfunction. +** +** Despite these problems, this approach is adopted as it seems simpler +** than the alternatives. +** +** INSERT operations: +** +** I.1) For each FK for which the table is the child table, search +** the parent table for a match. If none is found increment the +** constraint counter. +** +** I.2) For each FK for which the table is the parent table, +** search the child table for rows that correspond to the new +** row in the parent table. Decrement the counter for each row +** found (as the constraint is now satisfied). +** +** DELETE operations: +** +** D.1) For each FK for which the table is the child table, +** search the parent table for a row that corresponds to the +** deleted row in the child table. If such a row is not found, +** decrement the counter. +** +** D.2) For each FK for which the table is the parent table, search +** the child table for rows that correspond to the deleted row +** in the parent table. For each found increment the counter. +** +** UPDATE operations: +** +** An UPDATE command requires that all 4 steps above are taken, but only +** for FK constraints for which the affected columns are actually +** modified (values must be compared at runtime). +** +** Note that I.1 and D.1 are very similar operations, as are I.2 and D.2. +** This simplifies the implementation a bit. +** +** For the purposes of immediate FK constraints, the OR REPLACE conflict +** resolution is considered to delete rows before the new row is inserted. +** If a delete caused by OR REPLACE violates an FK constraint, an exception +** is thrown, even if the FK constraint would be satisfied after the new +** row is inserted. +** +** Immediate constraints are usually handled similarly. The only difference +** is that the counter used is stored as part of each individual statement +** object (struct Vdbe). If, after the statement has run, its immediate +** constraint counter is greater than zero, it returns SQLITE_CONSTRAINT +** and the statement transaction is rolled back. An exception is an INSERT +** statement that inserts a single row only (no triggers). In this case, +** instead of using a counter, an exception is thrown immediately if the +** INSERT violates a foreign key constraint. This is necessary as such +** an INSERT does not open a statement transaction. +** +** TODO: How should dropping a table be handled? How should renaming a +** table be handled? +** +** +** Query API Notes +** --------------- +** +** Before coding an UPDATE or DELETE row operation, the code-generator +** for those two operations needs to know whether or not the operation +** requires any FK processing and, if so, which columns of the original +** row are required by the FK processing VDBE code (i.e. if FKs were +** implemented using triggers, which of the old.* columns would be +** accessed). No information is required by the code-generator before +** coding an INSERT operation. The functions used by the UPDATE/DELETE +** generation code to query for this information are: +** +** sqlite3FkRequired() - Test to see if FK processing is required. +** sqlite3FkOldmask() - Query for the set of required old.* columns. +** +** +** Externally accessible module functions +** -------------------------------------- +** +** sqlite3FkCheck() - Check for foreign key violations. +** sqlite3FkActions() - Code triggers for ON UPDATE/ON DELETE actions. +** sqlite3FkDelete() - Delete an FKey structure. +*/ + +/* +** VDBE Calling Convention +** ----------------------- +** +** Example: +** +** For the following INSERT statement: +** +** CREATE TABLE t1(a, b INTEGER PRIMARY KEY, c); +** INSERT INTO t1 VALUES(1, 2, 3.1); +** +** Register (x): 2 (type integer) +** Register (x+1): 1 (type integer) +** Register (x+2): NULL (type NULL) +** Register (x+3): 3.1 (type real) +*/ + +/* +** A foreign key constraint requires that the key columns in the parent +** table are collectively subject to a UNIQUE or PRIMARY KEY constraint. +** Given that pParent is the parent table for foreign key constraint pFKey, +** search the schema a unique index on the parent key columns. +** +** If successful, zero is returned. If the parent key is an INTEGER PRIMARY +** KEY column, then output variable *ppIdx is set to NULL. Otherwise, *ppIdx +** is set to point to the unique index. +** +** If the parent key consists of a single column (the foreign key constraint +** is not a composite foreign key), output variable *paiCol is set to NULL. +** Otherwise, it is set to point to an allocated array of size N, where +** N is the number of columns in the parent key. The first element of the +** array is the index of the child table column that is mapped by the FK +** constraint to the parent table column stored in the left-most column +** of index *ppIdx. The second element of the array is the index of the +** child table column that corresponds to the second left-most column of +** *ppIdx, and so on. +** +** If the required index cannot be found, either because: +** +** 1) The named parent key columns do not exist, or +** +** 2) The named parent key columns do exist, but are not subject to a +** UNIQUE or PRIMARY KEY constraint, or +** +** 3) No parent key columns were provided explicitly as part of the +** foreign key definition, and the parent table does not have a +** PRIMARY KEY, or +** +** 4) No parent key columns were provided explicitly as part of the +** foreign key definition, and the PRIMARY KEY of the parent table +** consists of a a different number of columns to the child key in +** the child table. +** +** then non-zero is returned, and a "foreign key mismatch" error loaded +** into pParse. If an OOM error occurs, non-zero is returned and the +** pParse->db->mallocFailed flag is set. +*/ +static int locateFkeyIndex( + Parse *pParse, /* Parse context to store any error in */ + Table *pParent, /* Parent table of FK constraint pFKey */ + FKey *pFKey, /* Foreign key to find index for */ + Index **ppIdx, /* OUT: Unique index on parent table */ + int **paiCol /* OUT: Map of index columns in pFKey */ +){ + Index *pIdx = 0; /* Value to return via *ppIdx */ + int *aiCol = 0; /* Value to return via *paiCol */ + int nCol = pFKey->nCol; /* Number of columns in parent key */ + char *zKey = pFKey->aCol[0].zCol; /* Name of left-most parent key column */ + + /* The caller is responsible for zeroing output parameters. */ + assert( ppIdx && *ppIdx==0 ); + assert( !paiCol || *paiCol==0 ); + assert( pParse ); + + /* If this is a non-composite (single column) foreign key, check if it + ** maps to the INTEGER PRIMARY KEY of table pParent. If so, leave *ppIdx + ** and *paiCol set to zero and return early. + ** + ** Otherwise, for a composite foreign key (more than one column), allocate + ** space for the aiCol array (returned via output parameter *paiCol). + ** Non-composite foreign keys do not require the aiCol array. + */ + if( nCol==1 ){ + /* The FK maps to the IPK if any of the following are true: + ** + ** 1) There is an INTEGER PRIMARY KEY column and the FK is implicitly + ** mapped to the primary key of table pParent, or + ** 2) The FK is explicitly mapped to a column declared as INTEGER + ** PRIMARY KEY. + */ + if( pParent->iPKey>=0 ){ + if( !zKey ) return 0; + if( !sqlite3StrICmp(pParent->aCol[pParent->iPKey].zName, zKey) ) return 0; + } + }else if( paiCol ){ + assert( nCol>1 ); + aiCol = (int *)sqlite3DbMallocRaw(pParse->db, nCol*sizeof(int)); + if( !aiCol ) return 1; + *paiCol = aiCol; + } + + for(pIdx=pParent->pIndex; pIdx; pIdx=pIdx->pNext){ + if( pIdx->nColumn==nCol && pIdx->onError!=OE_None ){ + /* pIdx is a UNIQUE index (or a PRIMARY KEY) and has the right number + ** of columns. If each indexed column corresponds to a foreign key + ** column of pFKey, then this index is a winner. */ + + if( zKey==0 ){ + /* If zKey is NULL, then this foreign key is implicitly mapped to + ** the PRIMARY KEY of table pParent. The PRIMARY KEY index may be + ** identified by the test (Index.autoIndex==2). */ + if( pIdx->autoIndex==2 ){ + if( aiCol ){ + int i; + for(i=0; i<nCol; i++) aiCol[i] = pFKey->aCol[i].iFrom; + } + break; + } + }else{ + /* If zKey is non-NULL, then this foreign key was declared to + ** map to an explicit list of columns in table pParent. Check if this + ** index matches those columns. Also, check that the index uses + ** the default collation sequences for each column. */ + int i, j; + for(i=0; i<nCol; i++){ + int iCol = pIdx->aiColumn[i]; /* Index of column in parent tbl */ + char *zDfltColl; /* Def. collation for column */ + char *zIdxCol; /* Name of indexed column */ + + /* If the index uses a collation sequence that is different from + ** the default collation sequence for the column, this index is + ** unusable. Bail out early in this case. */ + zDfltColl = pParent->aCol[iCol].zColl; + if( !zDfltColl ){ + zDfltColl = "BINARY"; + } + if( sqlite3StrICmp(pIdx->azColl[i], zDfltColl) ) break; + + zIdxCol = pParent->aCol[iCol].zName; + for(j=0; j<nCol; j++){ + if( sqlite3StrICmp(pFKey->aCol[j].zCol, zIdxCol)==0 ){ + if( aiCol ) aiCol[i] = pFKey->aCol[j].iFrom; + break; + } + } + if( j==nCol ) break; + } + if( i==nCol ) break; /* pIdx is usable */ + } + } + } + + if( !pIdx ){ + if( !pParse->disableTriggers ){ + sqlite3ErrorMsg(pParse, "foreign key mismatch"); + } + sqlite3DbFree(pParse->db, aiCol); + return 1; + } + + *ppIdx = pIdx; + return 0; +} + +/* +** This function is called when a row is inserted into or deleted from the +** child table of foreign key constraint pFKey. If an SQL UPDATE is executed +** on the child table of pFKey, this function is invoked twice for each row +** affected - once to "delete" the old row, and then again to "insert" the +** new row. +** +** Each time it is called, this function generates VDBE code to locate the +** row in the parent table that corresponds to the row being inserted into +** or deleted from the child table. If the parent row can be found, no +** special action is taken. Otherwise, if the parent row can *not* be +** found in the parent table: +** +** Operation | FK type | Action taken +** -------------------------------------------------------------------------- +** INSERT immediate Increment the "immediate constraint counter". +** +** DELETE immediate Decrement the "immediate constraint counter". +** +** INSERT deferred Increment the "deferred constraint counter". +** +** DELETE deferred Decrement the "deferred constraint counter". +** +** These operations are identified in the comment at the top of this file +** (fkey.c) as "I.1" and "D.1". +*/ +static void fkLookupParent( + Parse *pParse, /* Parse context */ + int iDb, /* Index of database housing pTab */ + Table *pTab, /* Parent table of FK pFKey */ + Index *pIdx, /* Unique index on parent key columns in pTab */ + FKey *pFKey, /* Foreign key constraint */ + int *aiCol, /* Map from parent key columns to child table columns */ + int regData, /* Address of array containing child table row */ + int nIncr, /* Increment constraint counter by this */ + int isIgnore /* If true, pretend pTab contains all NULL values */ +){ + int i; /* Iterator variable */ + Vdbe *v = sqlite3GetVdbe(pParse); /* Vdbe to add code to */ + int iCur = pParse->nTab - 1; /* Cursor number to use */ + int iOk = sqlite3VdbeMakeLabel(v); /* jump here if parent key found */ + + /* If nIncr is less than zero, then check at runtime if there are any + ** outstanding constraints to resolve. If there are not, there is no need + ** to check if deleting this row resolves any outstanding violations. + ** + ** Check if any of the key columns in the child table row are NULL. If + ** any are, then the constraint is considered satisfied. No need to + ** search for a matching row in the parent table. */ + if( nIncr<0 ){ + sqlite3VdbeAddOp2(v, OP_FkIfZero, pFKey->isDeferred, iOk); + } + for(i=0; i<pFKey->nCol; i++){ + int iReg = aiCol[i] + regData + 1; + sqlite3VdbeAddOp2(v, OP_IsNull, iReg, iOk); + } + + if( isIgnore==0 ){ + if( pIdx==0 ){ + /* If pIdx is NULL, then the parent key is the INTEGER PRIMARY KEY + ** column of the parent table (table pTab). */ + int iMustBeInt; /* Address of MustBeInt instruction */ + int regTemp = sqlite3GetTempReg(pParse); + + /* Invoke MustBeInt to coerce the child key value to an integer (i.e. + ** apply the affinity of the parent key). If this fails, then there + ** is no matching parent key. Before using MustBeInt, make a copy of + ** the value. Otherwise, the value inserted into the child key column + ** will have INTEGER affinity applied to it, which may not be correct. */ + sqlite3VdbeAddOp2(v, OP_SCopy, aiCol[0]+1+regData, regTemp); + iMustBeInt = sqlite3VdbeAddOp2(v, OP_MustBeInt, regTemp, 0); + + /* If the parent table is the same as the child table, and we are about + ** to increment the constraint-counter (i.e. this is an INSERT operation), + ** then check if the row being inserted matches itself. If so, do not + ** increment the constraint-counter. */ + if( pTab==pFKey->pFrom && nIncr==1 ){ + sqlite3VdbeAddOp3(v, OP_Eq, regData, iOk, regTemp); + } + + sqlite3OpenTable(pParse, iCur, iDb, pTab, OP_OpenRead); + sqlite3VdbeAddOp3(v, OP_NotExists, iCur, 0, regTemp); + sqlite3VdbeAddOp2(v, OP_Goto, 0, iOk); + sqlite3VdbeJumpHere(v, sqlite3VdbeCurrentAddr(v)-2); + sqlite3VdbeJumpHere(v, iMustBeInt); + sqlite3ReleaseTempReg(pParse, regTemp); + }else{ + int nCol = pFKey->nCol; + int regTemp = sqlite3GetTempRange(pParse, nCol); + int regRec = sqlite3GetTempReg(pParse); + KeyInfo *pKey = sqlite3IndexKeyinfo(pParse, pIdx); + + sqlite3VdbeAddOp3(v, OP_OpenRead, iCur, pIdx->tnum, iDb); + sqlite3VdbeChangeP4(v, -1, (char*)pKey, P4_KEYINFO_HANDOFF); + for(i=0; i<nCol; i++){ + sqlite3VdbeAddOp2(v, OP_Copy, aiCol[i]+1+regData, regTemp+i); + } + + /* If the parent table is the same as the child table, and we are about + ** to increment the constraint-counter (i.e. this is an INSERT operation), + ** then check if the row being inserted matches itself. If so, do not + ** increment the constraint-counter. + ** + ** If any of the parent-key values are NULL, then the row cannot match + ** itself. So set JUMPIFNULL to make sure we do the OP_Found if any + ** of the parent-key values are NULL (at this point it is known that + ** none of the child key values are). + */ + if( pTab==pFKey->pFrom && nIncr==1 ){ + int iJump = sqlite3VdbeCurrentAddr(v) + nCol + 1; + for(i=0; i<nCol; i++){ + int iChild = aiCol[i]+1+regData; + int iParent = pIdx->aiColumn[i]+1+regData; + assert( aiCol[i]!=pTab->iPKey ); + if( pIdx->aiColumn[i]==pTab->iPKey ){ + /* The parent key is a composite key that includes the IPK column */ + iParent = regData; + } + sqlite3VdbeAddOp3(v, OP_Ne, iChild, iJump, iParent); + sqlite3VdbeChangeP5(v, SQLITE_JUMPIFNULL); + } + sqlite3VdbeAddOp2(v, OP_Goto, 0, iOk); + } + + sqlite3VdbeAddOp3(v, OP_MakeRecord, regTemp, nCol, regRec); + sqlite3VdbeChangeP4(v, -1, sqlite3IndexAffinityStr(v,pIdx), P4_TRANSIENT); + sqlite3VdbeAddOp4Int(v, OP_Found, iCur, iOk, regRec, 0); + + sqlite3ReleaseTempReg(pParse, regRec); + sqlite3ReleaseTempRange(pParse, regTemp, nCol); + } + } + + if( !pFKey->isDeferred && !pParse->pToplevel && !pParse->isMultiWrite ){ + /* Special case: If this is an INSERT statement that will insert exactly + ** one row into the table, raise a constraint immediately instead of + ** incrementing a counter. This is necessary as the VM code is being + ** generated for will not open a statement transaction. */ + assert( nIncr==1 ); + sqlite3HaltConstraint( + pParse, OE_Abort, "foreign key constraint failed", P4_STATIC + ); + }else{ + if( nIncr>0 && pFKey->isDeferred==0 ){ + sqlite3ParseToplevel(pParse)->mayAbort = 1; + } + 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; + iCol = pIdx->aiColumn[i]; + pCol = &pTab->aCol[iCol]; + if( pTab->iPKey==iCol ) iCol = -1; + pLeft->iTable = regData+iCol+1; + pLeft->affinity = pCol->affinity; + pLeft->pColl = sqlite3LocateCollSeq(pParse, pCol->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); + 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 ) 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. */ + sqlite3VdbeAddOp2(v, OP_FkIfZero, 0, sqlite3VdbeCurrentAddr(v)+2); + sqlite3HaltConstraint( + pParse, OE_Abort, "foreign key constraint failed", P4_STATIC + ); + + if( iSkip ){ + sqlite3VdbeResolveLabel(v, iSkip); + } + } +} + +/* +** 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 */ +){ + 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; + + /* 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 || locateFkeyIndex(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( !pFKey->isDeferred && !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( locateFkeyIndex(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; + locateFkeyIndex(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. */ + int i; + FKey *p; + + /* Check if any child key columns are being modified. */ + for(p=pTab->pFKey; p; p=p->pNextFrom){ + for(i=0; i<p->nCol; i++){ + int iChildKey = p->aCol[i].iFrom; + if( aChange[iChildKey]>=0 ) return 1; + if( iChildKey==pTab->iPKey && chngRowid ) return 1; + } + } + + /* Check if any parent key columns are being modified. */ + for(p=sqlite3FkReferences(pTab); p; p=p->pNextTo){ + for(i=0; i<p->nCol; i++){ + char *zKey = p->aCol[i].zCol; + int iKey; + for(iKey=0; iKey<pTab->nCol; iKey++){ + Column *pCol = &pTab->aCol[iKey]; + if( (zKey ? !sqlite3StrICmp(pCol->zName, zKey) : pCol->isPrimKey) ){ + if( aChange[iKey]>=0 ) return 1; + if( iKey==pTab->iPKey && 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( locateFkeyIndex(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 */ +){ + /* 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){ + Trigger *pAction = fkActionTrigger(pParse, pTab, pFKey, pChanges); + if( pAction ){ + sqlite3CodeRowTriggerDirect(pParse, pAction, 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 */ |