SQL: fix + test handling columns argument in read_table

Author: jorisvandenbossche

pandas/io/sql.py

@@ -340,7 +340,8 @@ def read_table(table_name, con, meta=None, index_col=None, coerce_float=True,
     table = pandas_sql.read_table(table_name,
                                   index_col=index_col,
                                   coerce_float=coerce_float,
-                                  parse_dates=parse_dates)
+                                  parse_dates=parse_dates,
+                                  columns=columns)
 
     if table is not None:
         return table

pandas/io/tests/test_sql.py

@@ -460,7 +460,9 @@ def test_date_and_index(self):
             issubclass(df.IntDateCol.dtype.type, np.datetime64),
             "IntDateCol loaded with incorrect type")
 
+
 class TestSQLApi(_TestSQLApi):
+
     """Test the public API as it would be used directly
     """
     flavor = 'sqlite'
@@ -501,8 +503,18 @@ def test_to_sql_index_label(self):
         self.assertEqual(frame.columns[0], 'other_label',
                          "Specified index_label not written to database")
 
+    def test_read_table_columns(self):
+        # test columns argument in read_table
+        sql.to_sql(self.test_frame1, 'test_frame', self.conn)
+
+        cols = ['A', 'B']
+        result = sql.read_table('test_frame', self.conn, columns=cols)
+        self.assertEqual(result.columns.tolist(), cols,
+                         "Columns not correctly selected")
+
 
 class TestSQLLegacyApi(_TestSQLApi):
+
     """Test the public legacy API
     """
     flavor = 'sqlite'