BUG: Fixes GH34411

pd.read_sql now returns a list with an empty pd.DataFrame if chunksize is greater
than 0 and the query returns 0 results.

Author: JohanKahrstrom

pandas/io/sql.py

@@ -1245,7 +1245,7 @@ def _query_iterator(
                         columns,
                         index_col=index_col,
                         coerce_float=coerce_float,
-                        parse_dates=parse_dates
+                        parse_dates=parse_dates,
                     )
                 break
             else:

pandas/tests/io/test_sql.py

@@ -602,12 +602,13 @@ def test_read_sql_view(self):
         self._check_iris_loaded_frame(iris_frame)
 
     def test_read_sql_with_chunksize_no_result(self):
-        with_batch = sql.read_sql_query("SELECT * FROM iris_view WHERE SepalLength < 0.0", self.conn, chunksize=5)
-        without_batch = sql.read_sql_query("SELECT * FROM iris_view WHERE SepalLength < 0.0", self.conn)
-        tm.assert_frame_equal(
-            pd.concat(with_batch),
-            without_batch
+        with_batch = sql.read_sql_query(
+            "SELECT * FROM iris_view WHERE SepalLength < 0.0", self.conn, chunksize=5
         )
+        without_batch = sql.read_sql_query(
+            "SELECT * FROM iris_view WHERE SepalLength < 0.0", self.conn
+        )
+        tm.assert_frame_equal(pd.concat(with_batch), without_batch)
 
     def test_to_sql(self):
         sql.to_sql(self.test_frame1, "test_frame1", self.conn)