Fix: selecting from table with same name as cte

sqlglot/optimizer/scope.py

@@ -620,7 +620,7 @@ def _traverse_tables(scope):
             table_name = expression.name
             source_name = expression.alias_or_name
 
-            if table_name in scope.sources:
+            if table_name in scope.sources and not expression.db:
                 # This is a reference to a parent source (e.g. a CTE), not an actual table, unless
                 # it is pivoted, because then we get back a new table and hence a new source.
                 pivots = expression.args.get("pivots")

tests/test_optimizer.py

@@ -198,6 +198,15 @@ def test_normalize(self):
         self.check_file("normalize", normalize)
 
     def test_qualify_columns(self):
+        self.assertEqual(
+            optimizer.qualify_columns.qualify_columns(
+                parse_one("WITH x AS (SELECT a FROM db.y) SELECT z FROM db.x"),
+                schema={"db": {"x": {"z": "int"}, "y": {"a": "int"}}},
+                infer_schema=False,
+            ).sql(),
+            "WITH x AS (SELECT y.a AS a FROM db.y) SELECT x.z AS z FROM db.x",
+        )
+
         self.assertEqual(
             optimizer.qualify_columns.qualify_columns(
                 parse_one("select y from x"),