/* ** Evaluate a view and store its result in an ephemeral table. The ** pWhere argument is an optional WHERE clause that restricts the ** set of rows in the view that are to be added to the ephemeral table. */ void sqlite3MaterializeView( Parse *pParse, /* Parsing context */ Table *pView, /* View definition */ Expr *pWhere, /* Optional WHERE clause to be added */ int iCur /* Cursor number for ephemeral table */ ){ SelectDest dest; Select *pSel; SrcList *pFrom; sqlite3 *db = pParse->db; int iDb = sqlite3SchemaToIndex(db, pView->pSchema); pWhere = sqlite3ExprDup(db, pWhere, 0); pFrom = sqlite3SrcListAppend(db, 0, 0, 0); if( pFrom ){ assert( pFrom->nSrc==1 ); pFrom->a[0].zName = sqlite3DbStrDup(db, pView->zName); pFrom->a[0].zDatabase = sqlite3DbStrDup(db, db->aDb[iDb].zDbSName); assert( pFrom->a[0].pOn==0 ); assert( pFrom->a[0].pUsing==0 ); } pSel = sqlite3SelectNew(pParse, 0, pFrom, pWhere, 0, 0, 0, SF_IncludeHidden, 0, 0); sqlite3SelectDestInit(&dest, SRT_EphemTab, iCur); sqlite3Select(pParse, pSel, &dest); sqlite3SelectDelete(db, pSel); }
/* ** Evaluate a view and store its result in an ephemeral table. The ** pWhere argument is an optional WHERE clause that restricts the ** set of rows in the view that are to be added to the ephemeral table. */ void sqlite3MaterializeView( Parse *pParse, /* Parsing context */ Table *pView, /* View definition */ Expr *pWhere, /* Optional WHERE clause to be added */ int iCur /* Cursor number for ephemerial table */ ){ SelectDest dest; Select *pDup; sqlite3 *db = pParse->db; pDup = sqlite3SelectDup(db, pView->pSelect, 0); if( pWhere ){ SrcList *pFrom; pWhere = sqlite3ExprDup(db, pWhere, 0); pFrom = sqlite3SrcListAppend(db, 0, 0, 0); if( pFrom ){ assert( pFrom->nSrc==1 ); pFrom->a[0].zAlias = sqlite3DbStrDup(db, pView->zName); pFrom->a[0].pSelect = pDup; assert( pFrom->a[0].pOn==0 ); assert( pFrom->a[0].pUsing==0 ); }else{ sqlite3SelectDelete(db, pDup); } pDup = sqlite3SelectNew(pParse, 0, pFrom, pWhere, 0, 0, 0, 0, 0, 0); if( pDup ) pDup->selFlags |= SF_Materialize; } sqlite3SelectDestInit(&dest, SRT_EphemTab, iCur); sqlite3Select(pParse, pDup, &dest); sqlite3SelectDelete(db, pDup); }
/* ** Convert the pStep->target token into a SrcList and return a pointer ** to that SrcList. ** ** This routine adds a specific database name, if needed, to the target when ** forming the SrcList. This prevents a trigger in one database from ** referring to a target in another database. An exception is when the ** trigger is in TEMP in which case it can refer to any other database it ** wants. */ static SrcList *targetSrcList( Parse *pParse, /* The parsing context */ TriggerStep *pStep /* The trigger containing the target token */ ){ Token sDb; /* Dummy database name token */ int iDb; /* Index of the database to use */ SrcList *pSrc; /* SrcList to be returned */ iDb = pStep->pTrig->iDb; if( iDb==0 || iDb>=2 ){ assert( iDb<pParse->db->nDb ); sDb.z = pParse->db->aDb[iDb].zName; sDb.n = strlen(sDb.z); pSrc = sqlite3SrcListAppend(0, &sDb, &pStep->target); } else { pSrc = sqlite3SrcListAppend(0, &pStep->target, 0); } return pSrc; }
/* ** Convert the pStep->target token into a SrcList and return a pointer ** to that SrcList. ** ** This routine adds a specific database name, if needed, to the target when ** forming the SrcList. This prevents a trigger in one database from ** referring to a target in another database. An exception is when the ** trigger is in TEMP in which case it can refer to any other database it ** wants. */ static SrcList *targetSrcList( Parse *pParse, /* The parsing context */ TriggerStep *pStep /* The trigger containing the target token */ ){ int iDb; /* Index of the database to use */ SrcList *pSrc; /* SrcList to be returned */ pSrc = sqlite3SrcListAppend(pParse->db, 0, &pStep->target, 0); if( pSrc ){ assert( pSrc->nSrc>0 ); assert( pSrc->a!=0 ); iDb = sqlite3SchemaToIndex(pParse->db, pStep->pTrig->pSchema); if( iDb==0 || iDb>=2 ){ sqlite3 *db = pParse->db; assert( iDb<pParse->db->nDb ); pSrc->a[pSrc->nSrc-1].zDatabase = sqlite3DbStrDup(db, db->aDb[iDb].zName); } } return pSrc; }
/* ** 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 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); } }