diff options
Diffstat (limited to 'src/select.c')
| -rw-r--r-- | src/select.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/src/select.c b/src/select.c index 95b2925e3..e2dd24b3e 100644 --- a/src/select.c +++ b/src/select.c @@ -3036,7 +3036,9 @@ static int multiSelect( int priorOp; /* The SRT_ operation to apply to prior selects */ Expr *pLimit; /* Saved values of p->nLimit */ int addr; + int emptyBypass = 0; /* IfEmpty opcode to bypass RHS */ SelectDest uniondest; + testcase( p->op==TK_EXCEPT ); testcase( p->op==TK_UNION ); @@ -3075,6 +3077,8 @@ static int multiSelect( */ if( p->op==TK_EXCEPT ){ op = SRT_Except; + emptyBypass = sqlite3VdbeAddOp1(v, OP_IfEmpty, unionTab); + VdbeCoverage(v); }else{ assert( p->op==TK_UNION ); op = SRT_Union; @@ -3117,6 +3121,7 @@ static int multiSelect( sqlite3VdbeResolveLabel(v, iCont); sqlite3VdbeAddOp2(v, OP_Next, unionTab, iStart); VdbeCoverage(v); sqlite3VdbeResolveLabel(v, iBreak); + if( emptyBypass ) sqlite3VdbeJumpHere(v, emptyBypass); sqlite3VdbeAddOp2(v, OP_Close, unionTab, 0); } break; @@ -3128,6 +3133,7 @@ static int multiSelect( int addr; SelectDest intersectdest; int r1; + int emptyBypass; /* INTERSECT is different from the others since it requires ** two temporary tables. Hence it has its own case. Begin @@ -3151,6 +3157,7 @@ static int multiSelect( if( rc ){ goto multi_select_end; } + emptyBypass = sqlite3VdbeAddOp1(v, OP_IfEmpty, tab1); VdbeCoverage(v); /* Code the current SELECT into temporary table "tab2" */ @@ -3194,6 +3201,7 @@ static int multiSelect( sqlite3VdbeAddOp2(v, OP_Next, tab1, iStart); VdbeCoverage(v); sqlite3VdbeResolveLabel(v, iBreak); sqlite3VdbeAddOp2(v, OP_Close, tab2, 0); + sqlite3VdbeJumpHere(v, emptyBypass); sqlite3VdbeAddOp2(v, OP_Close, tab1, 0); break; } |