异常处理

import traceback

import pymysql


def op_mysql(sql,many_tag=False):
    try:
        conn = pymysql.connect(host='118.24.3.40',user='jxz',password='123456',
                               db='jxz',port=3306,charset='utf8',
                               autocommit=True)
    except Exception as e:
        print('连接出错了~')
    else:
        cur = conn.cursor(pymysql.cursors.DictCursor)
        try:
            cur.execute(sql)
        except Exception as e:
            print(traceback.format_exc())
            print('sql语句出错了！')
        else:
            if many_tag:
                result = cur.fetchall() # [{"id":1,"name":"xxx"},{"id":2,"name":"xxx"}]
            else:
                result = cur.fetchone()
            return result
        finally:
            cur.close()
            conn.close()


def conn_mysql():
    conn = pymysql.connect(host='118.24.3.40', user='jxz', password='123456',
                           db='jxz', port=3306, charset='utf8',
                           autocommit=True)
    cur = conn.cursor(pymysql.cursors.DictCursor)
    return conn,cur

def execute_sql(cur,sql):
    cur.execute(sql)
    return cur.fetchone()

def execute_sql2(cur,sql):
    cur.execute(sql)
    return cur.fetchall()

def close_mysql(conn,cur):
    cur.close()
    conn.close()


class MySQL:
    def __init__(self):
        self.conn = pymysql.connect(host='118.24.3.40', user='jxz', password='123456',
                           db='jxz', port=3306, charset='utf8',
                           autocommit=True)
        self.cur = self.conn.cursor(pymysql.cursors.DictCursor)
    def __del__(self):
        self.cur.close()
        self.conn.close()
        print('连接已经被关闭了')

    def execute_one(self,sql):
        self.cur.execute(sql)
        return self.cur.fetchone()
    def execute_many(self,sql):
        self.cur.execute(sql)
        return self.cur.fetchall()


m = MySQL()
m.execute_one('show tables;')

import traceback
a = [1,2,3]
# print(a[5])

d = {"a":1}

try:
    print(d['key'])
    # 1/0
    a[5]
except Exception as e:
    print(traceback.format_exc())
    print("出异常了！！")
else:
    print('没有出错的情况下')
finally:
    print('什么时候走这里呢')#不管出错或者没出错都走这里