More fixes and comment updates.

FossilOrigin-Name: 38a9327bad1a01e3d7a47fad44ece2f6c7e88643

1 files changed, 36 insertions, 6 deletions

diff --git a/src/expr.c b/src/expr.c
index c50a2c077..08c22fffc 100644
--- a/src/expr.c
+++ b/src/expr.c
@@ -1398,7 +1398,6 @@ int sqlite3FindInIndex(Parse *pParse, Expr *pX, int *prNotFound){
     if( iCol<0 ){
       int iMem = ++pParse->nMem;
       int iAddr;
-      sqlite3VdbeUsesBtree(v, iDb);
 
       iAddr = sqlite3VdbeAddOp1(v, OP_If, iMem);
       sqlite3VdbeAddOp2(v, OP_Integer, 1, iMem);
@@ -1432,9 +1431,6 @@ int sqlite3FindInIndex(Parse *pParse, Expr *pX, int *prNotFound){
           char *pKey;
   
           pKey = (char *)sqlite3IndexKeyinfo(pParse, pIdx);
-          iDb = sqlite3SchemaToIndex(db, pIdx->pSchema);
-          sqlite3VdbeUsesBtree(v, iDb);
-
           iAddr = sqlite3VdbeAddOp1(v, OP_If, iMem);
           sqlite3VdbeAddOp2(v, OP_Integer, 1, iMem);
   
@@ -2559,14 +2555,48 @@ int sqlite3ExprCodeTarget(Parse *pParse, Expr *pExpr, int target){
     }
 
     case TK_TRIGGER: {
+      /* If the opcode is TK_TRIGGER, then the expression is a reference
+      ** to a column in the new.* or old.* pseudo-tables available to
+      ** trigger programs. In this case Expr.iTable is set to 1 for the
+      ** new.* pseudo-table, or 0 for the old.* pseudo-table. Expr.iColumn
+      ** is set to the column of the pseudo-table to read, or to -1 to
+      ** read the rowid field.
+      **
+      ** The expression is implemented using an OP_Param opcode. The p1
+      ** parameter is set to 0 for an old.rowid reference, or to (i+1)
+      ** to reference another column of the old.* pseudo-table, where 
+      ** i is the index of the column. For a new.rowid reference, p1 is
+      ** set to (n+1), where n is the number of columns in each pseudo-table.
+      ** For a reference to any other column in the new.* pseudo-table, p1
+      ** is set to (n+2+i), where n and i are as defined previously. For
+      ** example, if the table on which triggers are being fired is
+      ** declared as:
+      **
+      **   CREATE TABLE t1(a, b);
+      **
+      ** Then p1 is interpreted as follows:
+      **
+      **   p1==0   ->    old.rowid     p1==3   ->    new.rowid
+      **   p1==1   ->    old.a         p1==4   ->    new.a
+      **   p1==2   ->    old.b         p1==5   ->    new.b       
+      */
       Table *pTab = pExpr->pTab;
-      int iVal = pExpr->iTable * (pTab->nCol+1) + 1 + pExpr->iColumn;
-      sqlite3VdbeAddOp2(v, OP_Param, iVal, target);
+      int p1 = pExpr->iTable * (pTab->nCol+1) + 1 + pExpr->iColumn;
+
+      assert( pExpr->iTable==0 || pExpr->iTable==1 );
+      assert( pExpr->iColumn>=-1 && pExpr->iColumn<pTab->nCol );
+      assert( pTab->iPKey<0 || pExpr->iColumn!=pTab->iPKey );
+      assert( p1>=0 && p1<(pTab->nCol*2+2) );
+
+      sqlite3VdbeAddOp2(v, OP_Param, p1, target);
       VdbeComment((v, "%s.%s -> $%d",
         (pExpr->iTable ? "new" : "old"),
         (pExpr->iColumn<0 ? "rowid" : pExpr->pTab->aCol[pExpr->iColumn].zName),
         target
       ));
+
+      /* If the column has REAL affinity, it may currently be stored as an
+      ** integer. Use OP_RealAffinity to make sure it is really real.  */
       if( pExpr->iColumn>=0 
        && pTab->aCol[pExpr->iColumn].affinity==SQLITE_AFF_REAL
       ){