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:
 1 import psycopg2
 2 #finish the work with task schedule
 3 class dbwork:
 4     def __init__(self,work_content,dbname='taskschedule',user='rl_dev',password='123456', host='10.0.39.46',port=5432):
 5         self.dbname=dbname
 6         self.user=user
 7         self.password=password
 8         self.host=host
 9         self.port=port
10         self.work_content=work_content
11     def dowork(self):
12         conn=psycopg2.connect(database=self.dbname , user=self.user, password=self.password,host=self.host,port=self.port)
13         # Open a cursor to perform database operations
14         cur=conn.cursor()
15         # Execute a command: this creates a new table
16         sqlstr=self.work_content
17         #print 'sqlstr:'+sqlstr
18         if sqlstr.__contains__("update") or sqlstr.__contains__("UPDATE") or sqlstr.__contains__("delete") or sqlstr.__contains__("DELETE") or sqlstr.__contains__("insert") or sqlstr.__contains__("INSERT"):
19             cur.execute(sqlstr)
20             #if the sql action is a transaction, need to do commit
21             conn.commit()
22             cur.close()
23             conn.close()
24         else:
25             #if the sql action is not a transaction , return the result derectly
26             cur.execute(self.work_content)
27             result = cur.fetchall()
28               cur.close()
29             conn.close()
30             
31             return result
32 
33         #cur.execute("CREATE TABLE test (id serial PRIMARY KEY, num integer, data varchar);")