python执行数据库的一个简单函数

def my_db(host,user,passwd,db,sql,port=3306,charset='utf8'):
    import pymysql
    coon = pymysql.connect(user=user,host=host,port=port,passwd=passwd,
                           db=db,
                           charset=charset)
    cur = coon.cursor()#建立游标
    cur.execute(sql)#执行sql
    if sql.strip()[:6].upper()=='SELECT':
        res = cur.fetchall()
    else:
        coon.commit()
        res = 'ok'
    cur.close()
    coon.close()
    return res