fix: subquery selects (#1569)

sqlglot/expressions.py

@@ -846,11 +846,7 @@ def alias_column_names(self):
 
     @property
     def selects(self):
-        alias = self.args.get("alias")
-
-        if alias:
-            return alias.columns
-        return []
+        return self.this.selects if isinstance(self.this, Subqueryable) else []
 
     @property
     def named_selects(self):
@@ -920,7 +916,10 @@ def except_(self, expression, distinct=True, dialect=None, **opts):
 
 
 class UDTF(DerivedTable, Unionable):
-    pass
+    @property
+    def selects(self):
+        alias = self.args.get("alias")
+        return alias.columns if alias else []
 
 
 class Cache(Expression):

tests/test_expressions.py

@@ -297,6 +297,9 @@ def test_selects(self):
         expression = parse_one("SELECT a, b FROM x")
         self.assertEqual([s.sql() for s in expression.selects], ["a", "b"])
 
+        expression = parse_one("(SELECT a, b FROM x)")
+        self.assertEqual([s.sql() for s in expression.selects], ["a", "b"])
+
     def test_alias_column_names(self):
         expression = parse_one("SELECT * FROM (SELECT * FROM x) AS y")
         subquery = expression.find(exp.Subquery)

tests/test_optimizer.py

@@ -619,6 +619,12 @@ def test_concat_annotation(self):
         expression = annotate_types(parse_one("CONCAT('A', 'B')"))
         self.assertEqual(expression.type.this, exp.DataType.Type.VARCHAR)
 
+    def test_root_subquery_annotation(self):
+        expression = annotate_types(parse_one("(SELECT 1, 2 FROM x) LIMIT 0"))
+        self.assertIsInstance(expression, exp.Subquery)
+        self.assertEqual(exp.DataType.Type.INT, expression.selects[0].type.this)
+        self.assertEqual(exp.DataType.Type.INT, expression.selects[1].type.this)
+
     def test_recursive_cte(self):
         query = parse_one(
             """