diff options
Diffstat (limited to 'src/expr.c')
| -rw-r--r-- | src/expr.c | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/src/expr.c b/src/expr.c index 8f02ae569..ef4221ff8 100644 --- a/src/expr.c +++ b/src/expr.c @@ -3994,10 +3994,23 @@ expr_code_doover: break; } + /* TK_IF_NULL_ROW Expr nodes are inserted ahead of expressions + ** that derive from the right-hand table of a LEFT JOIN. The + ** Expr.iTable value is the table number for the right-hand table. + ** The expression is only evaluated if that table is not currently + ** on a LEFT JOIN NULL row. + */ case TK_IF_NULL_ROW: { int addrINR; + u8 okConstFactor = pParse->okConstFactor; addrINR = sqlite3VdbeAddOp1(v, OP_IfNullRow, pExpr->iTable); + /* Temporarily disable factoring of constant expressions, since + ** even though expressions may appear to be constant, they are not + ** really constant because they originate from the right-hand side + ** of a LEFT JOIN. */ + pParse->okConstFactor = 0; inReg = sqlite3ExprCodeTarget(pParse, pExpr->pLeft, target); + pParse->okConstFactor = okConstFactor; sqlite3VdbeJumpHere(v, addrINR); sqlite3VdbeChangeP3(v, addrINR, inReg); break; |