diff --git a/sql/string.go b/sql/string.go
index 73f64f7b..12939cac 100644
--- a/sql/string.go
+++ b/sql/string.go
@@ -802,7 +802,7 @@ func (this Polygon) JSON() string {
 
 func (this SubExpression) String() string {
 	switch this.Expr.(type) {
-	case IfelseStatement:
+	case *IfelseStatement:
 		return print("%v", this.Expr)
 	default:
 		return print("(%v)", this.Expr)