ENH: Allow to_sql to recognize single sql type pandas-dev#11886

PEP pandas-dev#3

Author: RahulHP

doc/source/whatsnew/v0.18.2.txt

@@ -74,6 +74,8 @@ Other enhancements
 
     pd.Timestamp(year=2012, month=1, day=1, hour=8, minute=30)
 
+- ``DataFrame.to_sql `` now allows a single value as the SQL type for all columns (:issue:`11886`).
+
 - The ``pd.read_csv()`` with ``engine='python'`` has gained support for the ``decimal`` option (:issue:`12933`)
 
 - ``Index.astype()`` now accepts an optional boolean argument ``copy``, which allows optional copying if the requirements on dtype are satisfied (:issue:`13209`)

pandas/io/sql.py

@@ -1233,14 +1233,15 @@ def to_sql(self, frame, name, if_exists='fail', index=True,
         chunksize : int, default None
             If not None, then rows will be written in batches of this size at a
             time.  If None, all rows will be written at once.
-        dtype : single SQL type or dict of column name to SQL type, default None
+        dtype : single SQL type or dict of column name to SQL type, default
+            None
             Optional specifying the datatype for columns. The SQL type should
-            be a SQLAlchemy type. If all columns are of the same type, one 
+            be a SQLAlchemy type. If all columns are of the same type, one
             single value can be used.
 
         """
         if dtype and not is_dictlike(dtype):
-            dtype = {col_name : dtype for col_name in frame}
+            dtype = {col_name: dtype for col_name in frame}
 
         if dtype is not None:
             from sqlalchemy.types import to_instance, TypeEngine
@@ -1650,15 +1651,15 @@ def to_sql(self, frame, name, if_exists='fail', index=True,
         chunksize : int, default None
             If not None, then rows will be written in batches of this
             size at a time. If None, all rows will be written at once.
-        dtype : single SQL type or dict of column name to SQL type, default None
+        dtype : single SQL type or dict of column name to SQL type, default
+            None
             Optional specifying the datatype for columns. The SQL type should
             be a string. If all columns are of the same type, one single value
             can be used.
 
         """
         if dtype and not is_dictlike(dtype):
-            dtype = {col_name : dtype for col_name in frame}
-            
+            dtype = {col_name: dtype for col_name in frame}
         if dtype is not None:
             for col, my_type in dtype.items():
                 if not isinstance(my_type, str):

pandas/io/tests/test_sql.py

@@ -1552,20 +1552,18 @@ def test_dtype(self):
         self.assertTrue(isinstance(sqltype, sqlalchemy.String))
         self.assertEqual(sqltype.length, 10)
 
-    def test_to_sql_save_indexgle_dtype(self):
-        self.drop('single_dtype_test')
-        cols = ['A','B']
-        data = [('a','b'),
-                ('c','d')]
-        df = DataFrame(data,columns=cols)
-        df.to_sql('single_dtype_test',self.conn,dtype=sqlalchemy.TEXT)
+    def test_to_sql_single_dtype(self):
+        cols = ['A', 'B']
+        data = [('a', 'b'),
+                ('c', 'd')]
+        df = DataFrame(data, columns=cols)
+        df.to_sql('single_dtype_test', self.conn, dtype=sqlalchemy.TEXT)
         meta = sqlalchemy.schema.MetaData(bind=self.conn)
         meta.reflect()
         sqltypea = meta.tables['single_dtype_test'].columns['A'].type
         sqltypeb = meta.tables['single_dtype_test'].columns['B'].type
         self.assertTrue(isinstance(sqltypea, sqlalchemy.TEXT))
         self.assertTrue(isinstance(sqltypeb, sqlalchemy.TEXT))
-        self.drop_table('single_dtype_test')
 
     def test_notnull_dtype(self):
         cols = {'Bool': Series([True, None]),
@@ -2044,15 +2042,17 @@ def test_to_sql_single_dtype(self):
         if self.flavor == 'mysql':
             raise nose.SkipTest('Not applicable to MySQL legacy')
         self.drop_table('single_dtype_test')
-        cols = ['A','B']
-        data = [('a','b'),
-                ('c','d')]
-        df = DataFrame(data,columns=cols)
-        df.to_sql('single_dtype_test',self.conn,dtype='STRING')
-        self.assertEqual(self._get_sqlite_column_type('single_dtype_test','A'),'STRING')
-        self.assertEqual(self._get_sqlite_column_type('single_dtype_test','B'),'STRING')
+        cols = ['A', 'B']
+        data = [('a', 'b'),
+                ('c', 'd')]
+        df = DataFrame(data, columns=cols)
+        df.to_sql('single_dtype_test', self.conn, dtype='STRING')
+        self.assertEqual(
+            self._get_sqlite_column_type('single_dtype_test', 'A'), 'STRING')
+        self.assertEqual(
+            self._get_sqlite_column_type('single_dtype_test', 'B'), 'STRING')
         self.drop_table('single_dtype_test')
-        
+
     def test_notnull_dtype(self):
         if self.flavor == 'mysql':
             raise nose.SkipTest('Not applicable to MySQL legacy')