use text for NULL literal

select fff(x) from (select null as x) a
Query Error: error: function fff(text) does not exist

1 files changed, 1 insertions, 1 deletions

diff --git a/ydb/library/yql/sql/pg/pg_sql.cpp b/ydb/library/yql/sql/pg/pg_sql.cpp
index 09a81af7e70..b3b8e853ae4 100644
--- a/ydb/library/yql/sql/pg/pg_sql.cpp
+++ b/ydb/library/yql/sql/pg/pg_sql.cpp
@@ -1472,7 +1472,7 @@ public:
             return L(A("PgConst"), QAX(ToString(StrVal(val))), L(A("PgType"), QA("text")));
         }
         case T_Null: {
-            return L(A("Null"));
+            return L(A("PgCast"), L(A("Null")), L(A("PgType"), QA("text")));
         }
         default:
             ValueNotImplemented(value, val);