Class to connect postgres with python in psycopg2

For we need to connect the postgres db in project very frequently, so write the follows class:

 import psycopg2
 #finish the work with task schedule
 class dbwork:
     def __init__(self,work_content,dbname='taskschedule',user='rl_dev',password='', host='10.0.39.46',port=5432):
         self.dbname=dbname
         self.user=user
         self.password=password
         self.host=host
         self.port=port
         self.work_content=work_content
     def dowork(self):
         conn=psycopg2.connect(database=self.dbname , user=self.user, password=self.password,host=self.host,port=self.port)
         # Open a cursor to perform database operations
         cur=conn.cursor()
         # Execute a command: this creates a new table
         sqlstr=self.work_content
         #print 'sqlstr:'+sqlstr
         if sqlstr.__contains__("update") or sqlstr.__contains__("UPDATE") or sqlstr.__contains__("delete") or sqlstr.__contains__("DELETE") or sqlstr.__contains__("insert") or sqlstr.__contains__("INSERT"):
             cur.execute(sqlstr)
             #if the sql action is a transaction, need to do commit
             conn.commit()
             cur.close()
             conn.close()
         else:
             #if the sql action is not a transaction , return the result derectly
             cur.execute(self.work_content)
             result = cur.fetchall()
               cur.close()
             conn.close()

             return result

         #cur.execute("CREATE TABLE test (id serial PRIMARY KEY, num integer, data varchar);")