feat(mysql): Add parser support for IS [NOT] NULL (#2651)

to return a boolean column

Author: Jille

internal/compiler/output_columns.go

@@ -173,12 +173,17 @@ func (c *Compiler) outputColumns(qc *QueryCatalog, node ast.Node) ([]*Column, er
 				name = *res.Name
 			}
 			notNull := false
-			if n.Boolop == ast.BoolExprTypeNot && len(n.Args.Items) == 1 {
-				sublink, ok := n.Args.Items[0].(*ast.SubLink)
-				if ok && sublink.SubLinkType == ast.EXISTS_SUBLINK {
+			if len(n.Args.Items) == 1 {
+				switch n.Boolop {
+				case ast.BoolExprTypeIsNull, ast.BoolExprTypeIsNotNull:
 					notNull = true
-					if name == "" {
-						name = "not_exists"
+				case ast.BoolExprTypeNot:
+					sublink, ok := n.Args.Items[0].(*ast.SubLink)
+					if ok && sublink.SubLinkType == ast.EXISTS_SUBLINK {
+						notNull = true
+						if name == "" {
+							name = "not_exists"
+						}
 					}
 				}
 			}

internal/endtoend/testdata/comparisons/mysql/go/query.sql.go

@@ -24,8 +24,8 @@ SELECT count(*) <> 0 FROM bar;
 -- name: Equal :many
 SELECT count(*) = 0 FROM bar;
 
+-- name: IsNull :many
+SELECT id IS NULL FROM bar;
 
-
-
-
-
+-- name: IsNotNull :many
+SELECT id IS NOT NULL FROM bar;

internal/endtoend/testdata/comparisons/mysql/query.sql

@@ -953,7 +953,18 @@ func (c *cc) convertIndexPartSpecification(n *pcast.IndexPartSpecification) ast.
 }
 
 func (c *cc) convertIsNullExpr(n *pcast.IsNullExpr) ast.Node {
-	return todo(n)
+	op := ast.BoolExprTypeIsNull
+	if n.Not {
+		op = ast.BoolExprTypeIsNotNull
+	}
+	return &ast.BoolExpr{
+		Boolop: op,
+		Args: &ast.List{
+			Items: []ast.Node{
+				c.convert(n.Expr),
+			},
+		},
+	}
 }
 
 func (c *cc) convertIsTruthExpr(n *pcast.IsTruthExpr) ast.Node {

internal/engine/dolphin/convert.go

@@ -6,6 +6,10 @@ const (
 	BoolExprTypeAnd
 	BoolExprTypeOr
 	BoolExprTypeNot
+
+	// Added for MySQL
+	BoolExprTypeIsNull
+	BoolExprTypeIsNotNull
 )
 
 type BoolExprType uint