ast: fix the behavior of window function (pingcap#236)

lyonzhi · Mar 11, 2019 · 32e93bd · 32e93bd
1 parent 4740ee2
commit 32e93bd
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Showing 5 changed files with 16 additions and 8 deletions.
diff --git a/ast/dml.go b/ast/dml.go
@@ -2009,12 +2009,19 @@ type WindowSpec struct {
 	PartitionBy *PartitionByClause
 	OrderBy     *OrderByClause
 	Frame       *FrameClause
+
+	// OnlyAlias will set to true of the first following case.
+	// To make compatiable with MySQL, we need to distinguish `select func over w` from `select func over (w)`.
+	OnlyAlias bool
 }
 
 // Restore implements Node interface.
 func (n *WindowSpec) Restore(ctx *RestoreCtx) error {
 	if name := n.Name.String(); name != "" {
 		ctx.WriteName(name)
+		if n.OnlyAlias {
+			return nil
+		}
 		ctx.WriteKeyWord(" AS ")
 	}
 	ctx.WritePlain("(")

diff --git a/ast/dml_test.go b/ast/dml_test.go
@@ -368,8 +368,9 @@ func (ts *testDMLSuite) TestWindowSpecRestore(c *C) {
 	RunNodeRestoreTest(c, testCases, "select rank() over w from t window %s", extractNodeFunc)
 
 	testCases = []NodeRestoreTestCase{
-		{"w", "(`w`)"},
+		{"w", "`w`"},
 		{"()", "()"},
+		{"(w)", "(`w`)"},
 		{"(w PARTITION BY country)", "(`w` PARTITION BY `country`)"},
 		{"(PARTITION BY a ROWS BETWEEN 1 PRECEDING AND 1 FOLLOWING)", "(PARTITION BY `a` ROWS BETWEEN 1 PRECEDING AND 1 FOLLOWING)"},
 	}

diff --git a/ast/functions_test.go b/ast/functions_test.go
@@ -123,16 +123,16 @@ func (ts *testFunctionsSuite) TestAggregateFuncExprRestore(c *C) {
 
 func (ts *testDMLSuite) TestWindowFuncExprRestore(c *C) {
 	testCases := []NodeRestoreTestCase{
-		{"RANK() OVER w", "RANK() OVER (`w`)"},
+		{"RANK() OVER w", "RANK() OVER `w`"},
 		{"RANK() OVER (PARTITION BY a)", "RANK() OVER (PARTITION BY `a`)"},
 		{"MAX(DISTINCT a) OVER (PARTITION BY a)", "MAX(DISTINCT `a`) OVER (PARTITION BY `a`)"},
 		{"MAX(DISTINCTROW a) OVER (PARTITION BY a)", "MAX(DISTINCT `a`) OVER (PARTITION BY `a`)"},
 		{"MAX(DISTINCT ALL a) OVER (PARTITION BY a)", "MAX(DISTINCT `a`) OVER (PARTITION BY `a`)"},
 		{"MAX(ALL a) OVER (PARTITION BY a)", "MAX(`a`) OVER (PARTITION BY `a`)"},
-		{"FIRST_VALUE(val) IGNORE NULLS OVER w", "FIRST_VALUE(`val`) IGNORE NULLS OVER (`w`)"},
-		{"FIRST_VALUE(val) RESPECT NULLS OVER w", "FIRST_VALUE(`val`) OVER (`w`)"},
-		{"NTH_VALUE(val, 233) FROM LAST IGNORE NULLS OVER w", "NTH_VALUE(`val`, 233) FROM LAST IGNORE NULLS OVER (`w`)"},
-		{"NTH_VALUE(val, 233) FROM FIRST IGNORE NULLS OVER w", "NTH_VALUE(`val`, 233) IGNORE NULLS OVER (`w`)"},
+		{"FIRST_VALUE(val) IGNORE NULLS OVER (w)", "FIRST_VALUE(`val`) IGNORE NULLS OVER (`w`)"},
+		{"FIRST_VALUE(val) RESPECT NULLS OVER w", "FIRST_VALUE(`val`) OVER `w`"},
+		{"NTH_VALUE(val, 233) FROM LAST IGNORE NULLS OVER w", "NTH_VALUE(`val`, 233) FROM LAST IGNORE NULLS OVER `w`"},
+		{"NTH_VALUE(val, 233) FROM FIRST IGNORE NULLS OVER (w)", "NTH_VALUE(`val`, 233) IGNORE NULLS OVER (`w`)"},
 	}
 	extractNodeFunc := func(node Node) Node {
 		return node.(*SelectStmt).Fields.Fields[0].Expr

diff --git a/parser.go b/parser.go
diff --git a/parser.y b/parser.y
@@ -4836,7 +4836,7 @@ WindowingClause:
 WindowNameOrSpec:
 	WindowName
 	{
-		$$ = ast.WindowSpec{Ref: $1.(model.CIStr)}
+		$$ = ast.WindowSpec{Name: $1.(model.CIStr), OnlyAlias: true,}
 	}
 |	WindowSpec
 	{