Postgresql example

examples/demo_postgresql.py

@@ -0,0 +1,13 @@
+from pandas import DataFrame
+from pandasql import PandaSQL
+
+# a dataframe
+df1 = DataFrame({"a": [1, 2, 3, 1], "b": [7, 1, 5, 3]})
+
+# establish postgresql connection using psycopg2 driver
+# log in with username: tubh; password: tubh; using unix socket at /tmp
+sqlClass = PandaSQL("postgresql+psycopg2://tubh:tubh@/tubh?host=/tmp")
+
+# try function GREATEST which is not supported by sqlite by is supported by postgresql
+result = sqlClass(("select GREATEST(tbl.a, tbl.b) as maxA_B from tbl"), {"tbl": df1})
+print(result)

pandasql/sqldf.py

@@ -1,7 +1,7 @@
 import inspect
 from contextlib import contextmanager
 from pandas.io.sql import to_sql, read_sql
-from sqlalchemy import create_engine
+from sqlalchemy import create_engine, text
 import re
 from warnings import catch_warnings, filterwarnings
 from sqlalchemy.exc import DatabaseError, ResourceClosedError
@@ -89,7 +89,7 @@ def conn(self):
 
     def _init_connection(self, conn):
         if self.engine.name == 'postgresql':
-            conn.execute('set search_path to pg_temp')
+            conn.execute(text('set search_path to pg_temp'))
 
     def _set_text_factory(self, dbapi_con, connection_record):
         dbapi_con.text_factory = str