DataBase Programming with Python:

import psycopg2
try:
        conn=psycopg2.connect("host=localhost dbname=databasename user=postgres password=postgres")
        mark=conn.cursor()
        mquery="select * from table"
        mark.execute(query)
# if it is selection query
        row1=mark.fetchall()
# if there exists any record
if(mark.rowcount):
            for row in row1:
                     print ( str( row[0] ) )

#Dont use like this.you need to catch specific exception.
#This will catch what ever exception arises   
except:
       print("Failed to connect to DB")
psycopg2 is a python module for connecting to Postgres database