use sql.null() instead of sql.literal_column('NULL')

diff --git a/lib/sqlalchemy/dialects/oracle/base.py b/lib/sqlalchemy/dialects/oracle/base.py
index e37f2f5399c17cc1e4851118a30754d4fcf97ffd..5e0ff6488338fe8a826e663ec2ff1993e4f59b16 100644 (file)
--- a/lib/sqlalchemy/dialects/oracle/base.py
+++ b/lib/sqlalchemy/dialects/oracle/base.py
@@ -2054,12 +2054,12 @@ class OracleDialect(default.DefaultDialect):
             (
                 dictionary.all_tables.c.compression
                 if self._supports_table_compression
-                else sql.literal_column("NULL").label("compression")
+                else sql.null().label("compression")
             ),
             (
                 dictionary.all_tables.c.compress_for
                 if self._supports_table_compress_for
-                else sql.literal_column("NULL").label("compress_for")
+                else sql.null().label("compress_for")
             ),
         ).where(dictionary.all_tables.c.owner == owner)
         if has_filter_names: