/*
** 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);
}
}
