/*
** Generate code for an UPDATE of a virtual table.
**
** The strategy is that we create an ephemerial table that contains
** for each row to be changed:
**
** (A) The original rowid of that row.
** (B) The revised rowid for the row. (note1)
** (C) The content of every column in the row.
**
** Then we loop over this ephemeral table and for each row in
** the ephermeral table call VUpdate.
**
** When finished, drop the ephemeral table.
**
** (note1) Actually, if we know in advance that (A) is always the same
** as (B) we only store (A), then duplicate (A) when pulling
** it out of the ephemeral table before calling VUpdate.
*/
static void updateVirtualTable(
Parse *pParse, /* The parsing context */
SrcList *pSrc, /* The virtual table to be modified */
Table *pTab, /* The virtual table */
ExprList *pChanges, /* The columns to change in the UPDATE statement */
Expr *pRowid, /* Expression used to recompute the rowid */
int *aXRef, /* Mapping from columns of pTab to entries in pChanges */
Expr *pWhere /* WHERE clause of the UPDATE statement */
){
Vdbe *v = pParse->pVdbe; /* Virtual machine under construction */
ExprList *pEList = 0; /* The result set of the SELECT statement */
Select *pSelect = 0; /* The SELECT statement */
Expr *pExpr; /* Temporary expression */
int ephemTab; /* Table holding the result of the SELECT */
int i; /* Loop counter */
int addr; /* Address of top of loop */
int iReg; /* First register in set passed to OP_VUpdate */
sqlite3 *db = pParse->db; /* Database connection */
const char *pVtab = (const char*)pTab->pVtab;
SelectDest dest;
/* Construct the SELECT statement that will find the new values for
** all updated rows.
*/
pEList = sqlite3ExprListAppend(pParse, 0,
sqlite3CreateIdExpr(pParse, "_rowid_"), 0);
if( pRowid ){
pEList = sqlite3ExprListAppend(pParse, pEList,
sqlite3ExprDup(db, pRowid), 0);
}
assert( pTab->iPKey<0 );
for(i=0; i<pTab->nCol; i++){
if( aXRef[i]>=0 ){
pExpr = sqlite3ExprDup(db, pChanges->a[aXRef[i]].pExpr);
}else{
pExpr = sqlite3CreateIdExpr(pParse, pTab->aCol[i].zName);
}
pEList = sqlite3ExprListAppend(pParse, pEList, pExpr, 0);
}
pSelect = sqlite3SelectNew(pParse, pEList, pSrc, pWhere, 0, 0, 0, 0, 0, 0);
/* Create the ephemeral table into which the update results will
** be stored.
*/
assert( v );
ephemTab = pParse->nTab++;
sqlite3VdbeAddOp2(v, OP_OpenEphemeral, ephemTab, pTab->nCol+1+(pRowid!=0));
/* fill the ephemeral table
*/
sqlite3SelectDestInit(&dest, SRT_Table, ephemTab);
sqlite3Select(pParse, pSelect, &dest);
/* Generate code to scan the ephemeral table and call VUpdate. */
iReg = ++pParse->nMem;
pParse->nMem += pTab->nCol+1;
sqlite3VdbeAddOp2(v, OP_Rewind, ephemTab, 0);
addr = sqlite3VdbeCurrentAddr(v);
sqlite3VdbeAddOp3(v, OP_Column, ephemTab, 0, iReg);
sqlite3VdbeAddOp3(v, OP_Column, ephemTab, (pRowid?1:0), iReg+1);
for(i=0; i<pTab->nCol; i++){
sqlite3VdbeAddOp3(v, OP_Column, ephemTab, i+1+(pRowid!=0), iReg+2+i);
}
sqlite3VtabMakeWritable(pParse, pTab);
sqlite3VdbeAddOp4(v, OP_VUpdate, 0, pTab->nCol+2, iReg, pVtab, P4_VTAB);
sqlite3VdbeAddOp2(v, OP_Next, ephemTab, addr);
sqlite3VdbeJumpHere(v, addr-1);
sqlite3VdbeAddOp2(v, OP_Close, ephemTab, 0);
/* Cleanup */
sqlite3SelectDelete(db, pSelect);
}
/*
** Generate code for an UPDATE of a virtual table.
**
** The strategy is that we create an ephemerial table that contains
** for each row to be changed:
**
** (A) The original rowid of that row.
** (B) The revised rowid for the row. (note1)
** (C) The content of every column in the row.
**
** Then we loop over this ephemeral table and for each row in
** the ephermeral table call VUpdate.
**
** When finished, drop the ephemeral table.
**
** (note1) Actually, if we know in advance that (A) is always the same
** as (B) we only store (A), then duplicate (A) when pulling
** it out of the ephemeral table before calling VUpdate.
*/
static void updateVirtualTable(
Parse *pParse, /* The parsing context */
SrcList *pSrc, /* The virtual table to be modified */
Table *pTab, /* The virtual table */
ExprList *pChanges, /* The columns to change in the UPDATE statement */
Expr *pRowid, /* Expression used to recompute the rowid */
int *aXRef, /* Mapping from columns of pTab to entries in pChanges */
Expr *pWhere /* WHERE clause of the UPDATE statement */
){
Vdbe *v = pParse->pVdbe; /* Virtual machine under construction */
ExprList *pEList = 0; /* The result set of the SELECT statement */
Select *pSelect = 0; /* The SELECT statement */
Expr *pExpr; /* Temporary expression */
int ephemTab; /* Table holding the result of the SELECT */
int i; /* Loop counter */
int addr; /* Address of top of loop */
/* Construct the SELECT statement that will find the new values for
** all updated rows.
*/
pEList = sqlite3ExprListAppend(0, sqlite3CreateIdExpr("_rowid_"), 0);
if( pRowid ){
pEList = sqlite3ExprListAppend(pEList, sqlite3ExprDup(pRowid), 0);
}
assert( pTab->iPKey<0 );
for(i=0; i<pTab->nCol; i++){
if( aXRef[i]>=0 ){
pExpr = sqlite3ExprDup(pChanges->a[aXRef[i]].pExpr);
}else{
pExpr = sqlite3CreateIdExpr(pTab->aCol[i].zName);
}
pEList = sqlite3ExprListAppend(pEList, pExpr, 0);
}
pSelect = sqlite3SelectNew(pEList, pSrc, pWhere, 0, 0, 0, 0, 0, 0);
/* Create the ephemeral table into which the update results will
** be stored.
*/
assert( v );
ephemTab = pParse->nTab++;
sqlite3VdbeAddOp(v, OP_OpenEphemeral, ephemTab, pTab->nCol+1+(pRowid!=0));
/* fill the ephemeral table
*/
sqlite3Select(pParse, pSelect, SRT_Table, ephemTab, 0, 0, 0, 0);
/*
** Generate code to scan the ephemeral table and call VDelete and
** VInsert
*/
sqlite3VdbeAddOp(v, OP_Rewind, ephemTab, 0);
addr = sqlite3VdbeCurrentAddr(v);
sqlite3VdbeAddOp(v, OP_Column, ephemTab, 0);
if( pRowid ){
sqlite3VdbeAddOp(v, OP_Column, ephemTab, 1);
}else{
sqlite3VdbeAddOp(v, OP_Dup, 0, 0);
}
for(i=0; i<pTab->nCol; i++){
sqlite3VdbeAddOp(v, OP_Column, ephemTab, i+1+(pRowid!=0));
}
pParse->pVirtualLock = pTab;
sqlite3VdbeOp3(v, OP_VUpdate, 0, pTab->nCol+2,
(const char*)pTab->pVtab, P3_VTAB);
sqlite3VdbeAddOp(v, OP_Next, ephemTab, addr);
sqlite3VdbeAddOp(v, OP_Close, ephemTab, 0);
/* Cleanup */
sqlite3SelectDelete(pSelect);
}
