Fix(postgres): enable qualification of queries using the ROWS FROM syntax (#4699)

Author: georgesittas

sqlglot/expressions.py

@@ -3250,7 +3250,7 @@ class Table(Expression):
 
     @property
     def name(self) -> str:
-        if isinstance(self.this, Func):
+        if not self.this or isinstance(self.this, Func):
             return ""
         return self.this.name
 

tests/fixtures/optimizer/qualify_columns.sql

@@ -254,6 +254,11 @@ START WITH (t1.id IS NOT NULL)
 CONNECT BY PRIOR t1.id = t2.id;
 WITH T1 AS (SELECT 1 AS C1, 1 AS C2, 'Y' AS TOP_PARENT_INDICATOR, 1 AS ID FROM DUAL DUAL), T2 AS (SELECT 1 AS C2, 2 AS ID FROM DUAL DUAL) SELECT T1.C1 AS C1 FROM T1 T1 LEFT JOIN T2 T2 ON T1.C2 = T2.C2 WHERE (T1.TOP_PARENT_INDICATOR = 'Y' OR LEVEL = 1) START WITH (NOT T1.ID IS NULL) CONNECT BY PRIOR T1.ID = T2.ID;
 
+# execute: false
+# dialect: postgres
+SELECT * FROM ROWS FROM (GENERATE_SERIES(1, 3), GENERATE_SERIES(10, 12)) AS t(a, b);
+SELECT t.a AS a, t.b AS b FROM ROWS FROM (GENERATE_SERIES(1, 3), GENERATE_SERIES(10, 12)) AS t(a, b);
+
 --------------------------------------
 -- Derived tables
 --------------------------------------