reset pingcap/tidb#7837

ast/expressions.go

@@ -442,8 +442,6 @@ type ExistsSubqueryExpr struct {
 	exprNode
 	// Sel is the subquery, may be rewritten to other type of expression.
 	Sel ExprNode
-	// Not is true, the expression is "not exists".
-	Not bool
 }
 
 // Format the ExprNode into a Writer.
@@ -700,8 +698,6 @@ type PositionExpr struct {
 	exprNode
 	// N is the position, started from 1 now.
 	N int
-	// P is the parameterized position.
-	P ExprNode
 	// Refer is the result field the position refers to.
 	Refer *ResultField
 }
@@ -718,13 +714,6 @@ func (n *PositionExpr) Accept(v Visitor) (Node, bool) {
 		return v.Leave(newNode)
 	}
 	n = newNode.(*PositionExpr)
-	if n.P != nil {
-		node, ok := n.P.Accept(v)
-		if !ok {
-			return n, false
-		}
-		n.P = node.(ExprNode)
-	}
 	return v.Leave(n)
 }
 

parser.y

@@ -2471,13 +2471,7 @@ Expression:
 	}
 |	"NOT" Expression %prec not
 	{
-		expr, ok := $2.(*ast.ExistsSubqueryExpr)
-		if ok {
-			expr.Not = true
-			$$ = $2
-		} else {
-			$$ = &ast.UnaryOperationExpr{Op: opcode.Not, V: $2}
-		}
+		$$ = &ast.UnaryOperationExpr{Op: opcode.Not, V: $2}
 	}
 |	BoolPri IsOrNotOp trueKwd %prec is
 	{

parser_test.go

@@ -2468,23 +2468,6 @@ func (s *testParserSuite) TestTablePartition(c *C) {
 	c.Assert(createTable.Partition.Definitions[0].Comment, Equals, "check")
 }
 
-func (s *testParserSuite) TestNotExistsSubquery(c *C) {
-	table := []testCase{
-		{`select * from t1 where not exists (select * from t2 where t1.a = t2.a)`, true},
-	}
-
-	parser := New()
-	for _, tt := range table {
-		stmt, err := parser.Parse(tt.src, "", "")
-		c.Assert(err, IsNil)
-
-		sel := stmt[0].(*ast.SelectStmt)
-		exists, ok := sel.Where.(*ast.ExistsSubqueryExpr)
-		c.Assert(ok, IsTrue)
-		c.Assert(exists.Not, Equals, tt.ok)
-	}
-}
-
 func (s *testParserSuite) TestWindowFunctionIdentifier(c *C) {
 	var table []testCase
 	s.enableWindowFunc = true