Fix sql-insert format emits NULL as 'None' (#1409)

* Sub: Fix issue #1408

Body:
1. Fix issue #1408 sql-insert format emits NULL as 'None';
2. Fix DUAL displays as ""DUAL"";

==== End ====

* Sub: Update changelog.rst

Body:

==== End ====

* Sub: Optimize if logic

Body:

==== End ====

changelog.rst

@@ -23,6 +23,7 @@ Bug fixes:
 * Fix \ev not producing a correctly quoted "schema"."view"
 * Fix 'invalid connection option "dsn"' ([issue 1373](https://github.com/dbcli/pgcli/issues/1373)).
 * Fix explain mode when used with `expand`, `auto_expand`, or `--explain-vertical-output` ([issue 1393](https://github.com/dbcli/pgcli/issues/1393)).
+* Fix sql-insert format emits NULL as 'None' ([issue 1408](https://github.com/dbcli/pgcli/issues/1408)).
 
 3.5.0 (2022/09/15):
 ===================

pgcli/auth.py

@@ -26,7 +26,9 @@ def keyring_initialize(keyring_enabled, *, logger):
 
         try:
             keyring = importlib.import_module("keyring")
-        except ModuleNotFoundError as e:
+        except (
+            ModuleNotFoundError
+        ) as e:  # ImportError for Python 2, ModuleNotFoundError for Python 3
             logger.warning("import keyring failed: %r.", e)
 
 

pgcli/packages/formatter/sqlformatter.py

@@ -14,10 +14,13 @@ preprocessors = ()
 
 
 def escape_for_sql_statement(value):
+    if value is None:
+        return "NULL"
+
     if isinstance(value, bytes):
         return f"X'{value.hex()}'"
-    else:
-        return "'{}'".format(value)
+
+    return "'{}'".format(value)
 
 
 def adapter(data, headers, table_format=None, **kwargs):
@@ -29,7 +32,7 @@ def adapter(data, headers, table_format=None, **kwargs):
         else:
             table_name = table[1]
     else:
-        table_name = '"DUAL"'
+        table_name = "DUAL"
     if table_format == "sql-insert":
         h = '", "'.join(headers)
         yield 'INSERT INTO "{}" ("{}") VALUES'.format(table_name, h)

tests/formatter/test_sqlformatter.py

@@ -34,7 +34,7 @@ def test_output_sql_insert():
             "Jackson",
             "jackson_test@gmail.com",
             "132454789",
-            "",
+            None,
             "2022-09-09 19:44:32.712343+08",
             "2022-09-09 19:44:32.712343+08",
         ]
@@ -58,7 +58,7 @@ def test_output_sql_insert():
     output_list = [l for l in output]
     expected = [
         'INSERT INTO "user" ("id", "name", "email", "phone", "description", "created_at", "updated_at") VALUES',
-        "  ('1', 'Jackson', 'jackson_test@gmail.com', '132454789', '', "
+        "  ('1', 'Jackson', 'jackson_test@gmail.com', '132454789', NULL, "
         + "'2022-09-09 19:44:32.712343+08', '2022-09-09 19:44:32.712343+08')",
         ";",
     ]