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Diffstat (limited to 'lib/libsqlite3/src/fkey.c')
| -rw-r--r-- | lib/libsqlite3/src/fkey.c | 1410 |
1 files changed, 0 insertions, 1410 deletions
diff --git a/lib/libsqlite3/src/fkey.c b/lib/libsqlite3/src/fkey.c deleted file mode 100644 index b55e2a98138..00000000000 --- a/lib/libsqlite3/src/fkey.c +++ /dev/null @@ -1,1410 +0,0 @@ -/* -** -** 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_FOREIGNKEY 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_FOREIGNKEY -** 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 for 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 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. -*/ -int sqlite3FkLocateIndex( - 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->nKeyCol==nCol && IsUniqueIndex(pIdx) ){ - /* 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. */ - if( IsPrimaryKeyIndex(pIdx) ){ - 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++){ - i16 iCol = pIdx->aiColumn[i]; /* Index of column in parent tbl */ - char *zDfltColl; /* Def. collation for column */ - char *zIdxCol; /* Name of indexed column */ - - if( iCol<0 ) break; /* No foreign keys against expression indexes */ - - /* 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 - \"%w\" referencing \"%w\"", - pFKey->pFrom->zName, pFKey->zTo); - } - 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); - VdbeCoverage(v); - } - for(i=0; i<pFKey->nCol; i++){ - int iReg = aiCol[i] + regData + 1; - sqlite3VdbeAddOp2(v, OP_IsNull, iReg, iOk); VdbeCoverage(v); - } - - 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); - VdbeCoverage(v); - - /* 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); VdbeCoverage(v); - sqlite3VdbeChangeP5(v, SQLITE_NOTNULL); - } - - sqlite3OpenTable(pParse, iCur, iDb, pTab, OP_OpenRead); - sqlite3VdbeAddOp3(v, OP_NotExists, iCur, 0, regTemp); VdbeCoverage(v); - sqlite3VdbeGoto(v, 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); - - sqlite3VdbeAddOp3(v, OP_OpenRead, iCur, pIdx->tnum, iDb); - sqlite3VdbeSetP4KeyInfo(pParse, pIdx); - 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( pIdx->aiColumn[i]>=0 ); - 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); VdbeCoverage(v); - sqlite3VdbeChangeP5(v, SQLITE_JUMPIFNULL); - } - sqlite3VdbeGoto(v, iOk); - } - - sqlite3VdbeAddOp4(v, OP_MakeRecord, regTemp, nCol, regRec, - sqlite3IndexAffinityStr(pParse->db,pIdx), nCol); - sqlite3VdbeAddOp4Int(v, OP_Found, iCur, iOk, regRec, 0); VdbeCoverage(v); - - sqlite3ReleaseTempReg(pParse, regRec); - sqlite3ReleaseTempRange(pParse, regTemp, nCol); - } - } - - if( !pFKey->isDeferred && !(pParse->db->flags & SQLITE_DeferFKs) - && !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, SQLITE_CONSTRAINT_FOREIGNKEY, - OE_Abort, 0, P4_STATIC, P5_ConstraintFK); - }else{ - if( nIncr>0 && pFKey->isDeferred==0 ){ - sqlite3MayAbort(pParse); - } - sqlite3VdbeAddOp2(v, OP_FkCounter, pFKey->isDeferred, nIncr); - } - - sqlite3VdbeResolveLabel(v, iOk); - sqlite3VdbeAddOp1(v, OP_Close, iCur); -} - - -/* -** Return an Expr object that refers to a memory register corresponding -** to column iCol of table pTab. -** -** regBase is the first of an array of register that contains the data -** for pTab. regBase itself holds the rowid. regBase+1 holds the first -** column. regBase+2 holds the second column, and so forth. -*/ -static Expr *exprTableRegister( - Parse *pParse, /* Parsing and code generating context */ - Table *pTab, /* The table whose content is at r[regBase]... */ - int regBase, /* Contents of table pTab */ - i16 iCol /* Which column of pTab is desired */ -){ - Expr *pExpr; - Column *pCol; - const char *zColl; - sqlite3 *db = pParse->db; - - pExpr = sqlite3Expr(db, TK_REGISTER, 0); - if( pExpr ){ - if( iCol>=0 && iCol!=pTab->iPKey ){ - pCol = &pTab->aCol[iCol]; - pExpr->iTable = regBase + iCol + 1; - pExpr->affinity = pCol->affinity; - zColl = pCol->zColl; - if( zColl==0 ) zColl = db->pDfltColl->zName; - pExpr = sqlite3ExprAddCollateString(pParse, pExpr, zColl); - }else{ - pExpr->iTable = regBase; - pExpr->affinity = SQLITE_AFF_INTEGER; - } - } - return pExpr; -} - -/* -** Return an Expr object that refers to column iCol of table pTab which -** has cursor iCur. -*/ -static Expr *exprTableColumn( - sqlite3 *db, /* The database connection */ - Table *pTab, /* The table whose column is desired */ - int iCursor, /* The open cursor on the table */ - i16 iCol /* The column that is wanted */ -){ - Expr *pExpr = sqlite3Expr(db, TK_COLUMN, 0); - if( pExpr ){ - pExpr->pTab = pTab; - pExpr->iTable = iCursor; - pExpr->iColumn = iCol; - } - return pExpr; -} - -/* -** 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. -** -** Parameter nIncr is passed -1 when inserting a row (as this may decrease -** the number of FK violations in the db) or +1 when deleting one (as this -** may increase the number of FK constraint problems). -** -** 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, /* The child table to be scanned */ - Table *pTab, /* The parent table */ - Index *pIdx, /* Index on parent covering the foreign key */ - FKey *pFKey, /* The foreign key linking pSrc to pTab */ - int *aiCol, /* Map from pIdx cols to child table cols */ - int regData, /* Parent row 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==0 || pIdx->pTable==pTab ); - assert( pIdx==0 || pIdx->nKeyCol==pFKey->nCol ); - assert( pIdx!=0 || pFKey->nCol==1 ); - assert( pIdx!=0 || HasRowid(pTab) ); - - if( nIncr<0 ){ - iFkIfZero = sqlite3VdbeAddOp2(v, OP_FkIfZero, pFKey->isDeferred, 0); - VdbeCoverage(v); - } - - /* 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) */ - i16 iCol; /* Index of column in child table */ - const char *zCol; /* Name of column in child table */ - - iCol = pIdx ? pIdx->aiColumn[i] : -1; - pLeft = exprTableRegister(pParse, pTab, regData, iCol); - 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, then add terms - ** to the WHERE clause that prevent this entry from being scanned. - ** The added WHERE clause terms are like this: - ** - ** $current_rowid!=rowid - ** NOT( $current_a==a AND $current_b==b AND ... ) - ** - ** The first form is used for rowid tables. The second form is used - ** for WITHOUT ROWID tables. In the second form, the primary key is - ** (a,b,...) - */ - if( pTab==pFKey->pFrom && nIncr>0 ){ - Expr *pNe; /* Expression (pLeft != pRight) */ - Expr *pLeft; /* Value from parent table row */ - Expr *pRight; /* Column ref to child table */ - if( HasRowid(pTab) ){ - pLeft = exprTableRegister(pParse, pTab, regData, -1); - pRight = exprTableColumn(db, pTab, pSrc->a[0].iCursor, -1); - pNe = sqlite3PExpr(pParse, TK_NE, pLeft, pRight, 0); - }else{ - Expr *pEq, *pAll = 0; - Index *pPk = sqlite3PrimaryKeyIndex(pTab); - assert( pIdx!=0 ); - for(i=0; i<pPk->nKeyCol; i++){ - i16 iCol = pIdx->aiColumn[i]; - assert( iCol>=0 ); - pLeft = exprTableRegister(pParse, pTab, regData, iCol); - pRight = exprTableColumn(db, pTab, pSrc->a[0].iCursor, iCol); - pEq = sqlite3PExpr(pParse, TK_EQ, pLeft, pRight, 0); - pAll = sqlite3ExprAnd(db, pAll, pEq); - } - pNe = sqlite3PExpr(pParse, TK_NOT, pAll, 0, 0); - } - pWhere = sqlite3ExprAnd(db, pWhere, pNe); - } - - /* 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. For each row found, increment either the deferred or immediate - ** foreign key constraint counter. */ - pWInfo = sqlite3WhereBegin(pParse, pSrc, pWhere, 0, 0, 0, 0); - 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 linked list of FKey objects (connected by -** FKey.pNextTo) holding all children of table pTab. 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){ - return (FKey *)sqlite3HashFind(&pTab->pSchema->fkeyHash, pTab->zName); -} - -/* -** 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); VdbeCoverage(v); - } - - 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); - VdbeCoverage(v); - sqlite3HaltConstraint(pParse, SQLITE_CONSTRAINT_FOREIGNKEY, - OE_Abort, 0, P4_STATIC, P5_ConstraintFK); - } - - 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; -} - -/* -** Return true if the parser passed as the first argument is being -** used to code a trigger that is really a "SET NULL" action belonging -** to trigger pFKey. -*/ -static int isSetNullAction(Parse *pParse, FKey *pFKey){ - Parse *pTop = sqlite3ParseToplevel(pParse); - if( pTop->pTriggerPrg ){ - Trigger *p = pTop->pTriggerPrg->pTrigger; - if( (p==pFKey->apTrigger[0] && pFKey->aAction[0]==OE_SetNull) - || (p==pFKey->apTrigger[1] && pFKey->aAction[1]==OE_SetNull) - ){ - 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 bIgnore = 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); VdbeCoverage(v); - } - 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; - } - assert( pIdx==0 || pIdx->aiColumn[i]>=0 ); -#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); - bIgnore = (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, bIgnore); - } - if( regNew!=0 && !isSetNullAction(pParse, pFKey) ){ - /* 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. - ** - ** If this operation is being performed as part of a trigger program - ** that is actually a "SET NULL" action belonging to this very - ** foreign key, then omit this scan altogether. As all child key - ** values are guaranteed to be NULL, it is not possible for adding - ** this row to cause an FK violation. */ - fkLookupParent(pParse, iDb, pTo, pIdx, pFKey, aiCol, regNew, +1, bIgnore); - } - - sqlite3DbFree(db, aiFree); - } - - /* Loop through all the foreign key constraints that refer to this table. - ** (the "child" constraints) */ - 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 (or fix) - ** 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 the child table. We need the - ** child table as a SrcList for sqlite3WhereBegin() */ - 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 ){ - int eAction = pFKey->aAction[aChange!=0]; - fkScanChildren(pParse, pSrc, pTab, pIdx, pFKey, aiCol, regOld, 1); - /* If this is a deferred FK constraint, or a CASCADE or SET NULL - ** action applies, then any foreign key violations caused by - ** removing the parent key will be rectified by the action trigger. - ** So do not set the "may-abort" flag in this case. - ** - ** Note 1: If the FK is declared "ON UPDATE CASCADE", then the - ** may-abort flag will eventually be set on this statement anyway - ** (when this function is called as part of processing the UPDATE - ** within the action trigger). - ** - ** Note 2: At first glance it may seem like SQLite could simply omit - ** all OP_FkCounter related scans when either CASCADE or SET NULL - ** applies. The trouble starts if the CASCADE or SET NULL action - ** trigger causes other triggers or action rules attached to the - ** child table to fire. In these cases the fk constraint counters - ** might be set incorrectly if any OP_FkCounter related scans are - ** omitted. */ - if( !pFKey->isDeferred && eAction!=OE_Cascade && eAction!=OE_SetNull ){ - sqlite3MayAbort(pParse); - } - } - 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->nKeyCol; i++){ - assert( pIdx->aiColumn[i]>=0 ); - 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 ); - assert( pIdx!=0 || (pTab->iPKey>=0 && pTab->iPKey<pTab->nCol) ); - assert( pIdx==0 || pIdx->aiColumn[i]>=0 ); - tToCol.z = pTab->aCol[pIdx ? pIdx->aiColumn[i] : pTab->iPKey].zName; - 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, - sqlite3ExprAlloc(db, TK_ID, &tOld, 0), - sqlite3ExprAlloc(db, TK_ID, &tToCol, 0) - , 0), - sqlite3ExprAlloc(db, TK_ID, &tFromCol, 0) - , 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, - sqlite3ExprAlloc(db, TK_ID, &tOld, 0), - sqlite3ExprAlloc(db, TK_ID, &tToCol, 0), - 0), - sqlite3PExpr(pParse, TK_DOT, - sqlite3ExprAlloc(db, TK_ID, &tNew, 0), - sqlite3ExprAlloc(db, TK_ID, &tToCol, 0), - 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, - sqlite3ExprAlloc(db, TK_ID, &tNew, 0), - sqlite3ExprAlloc(db, TK_ID, &tToCol, 0) - , 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->zTarget */ - ); - if( pTrigger ){ - pStep = pTrigger->step_list = (TriggerStep *)&pTrigger[1]; - pStep->zTarget = (char *)&pStep[1]; - memcpy((char *)pStep->zTarget, 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, 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 */ |