# connect_demo.py

import pymysql

db = pymysql.connect('localhost', 'root', 'root', 'imooc', charset='utf8')

cursor = db.cursor()

print(db)

print(cursor)

cursor.close()

db.close()

<pymysql.connections.Connection object at 0x7f1e2a852278>

<pymysql.cursors.Cursor object at 0x7f1e2880e668>

# cursor_demo.py

import pymysql

db = pymysql.connect('localhost', 'root', 'root', 'imooc', charset='utf8')

cursor = db.cursor()

sql = 'select * from user'

cursor.execute(sql)

print(cursor.rowcount)

result = cursor.fetchall()

print(result)

for row in result:

   print(row[0],':', row[1])

cursor.close()

db.close()

((, 'lisi'), (, 'zhangsan'), (, 'liuqi'), (, 'white'))

 : lisi

 : zhangsan

 : liuqi

 : white

# curd_demo.py

import pymysql

db = pymysql.connect('localhost', 'root', 'root', 'imooc', charset='utf8')

cursor = db.cursor()

sql_select = "select * from user"

sql_insert = "insert into user(userid, username) values(DEFAULT, 'wuliu')"

sql_update = "update user set username='liuqi' where userid=3"

sql_delete = "delete from user where userid>4"

cursor.execute(sql_select)

result = cursor.fetchall()

print(result)

try:

    cursor.execute(sql_insert)

    result = cursor.rowcount

    print(result)

    cursor.execute(sql_update)

    result = cursor.rowcount

    print(result)

    cursor.execute(sql_delete)

    result = cursor.rowcount

    print(result)

    db.commit()

except Exception as e:

    print(e)

    db.rollback()

cursor.close()

db.close()

((, 'lisi'), (, 'zhangsan'), (, 'liuqi'), (, 'white'))

# bank_demo.py

# coding:utf8

import sys

import pymysql

class TransferMoney(object):

    def __init__(self, conn):

        self.conn = conn

    def check_acct_available(self, acctid):

        cursor = self.conn.cursor()

        try:

            sql = "select * from account where acctid=%s" % acctid

            cursor.execute(sql)

            print("check_acct_available:" + sql)

            rs = cursor.fetchall()

            if len(rs) != 1:

                raise Exception("账号不存在" % acctid)

        finally:

            cursor.close()

    def has_enough_money(self, acctid, money):

        cursor = self.conn.cursor()

        try:

            sql = "select * from account where acctid=%s and money>%s" % (acctid, money)

            cursor.execute(sql)

            print("chas_enough_mone:" + sql)

            rs = cursor.fetchall()

            if len(rs) != 1:

                raise Exception("账号%s余额不足" % acctid)

        finally:

            cursor.close()

    def reduce_money(self, acctid, money):

        cursor = self.conn.cursor()

        try:

            sql = "update account set money=money - %s where acctid=%s" % (money, acctid)

            cursor.execute(sql)

            print("reduce_money:" + sql)

            if cursor.rowcount != 1:

                raise Exception("账号%s减款失败" % acctid)

        finally:

            cursor.close()

    def add_money(self, acctid, money):

        cursor = self.conn.cursor()

        try:

            sql = "update account set money=money + %s where acctid=%s" % (money, acctid)

            cursor.execute(sql)

            print("rad_money:" + sql)

            if cursor.rowcount != 1:

                raise Exception("账号%s加款失败" % acctid)

        finally:

            cursor.close()

    def transfer(self, source_acctid, target_acctid, money):

        try:

            self.check_acct_available(source_acctid)

            self.check_acct_available(target_acctid)

            self.has_enough_money(source_acctid, money)

            self.reduce_money(source_acctid, money)

            self.add_money(target_acctid, money)

            self.conn.commit()

        except Exception as e:

            self.conn.rollback()

            raise e

if __name__ == "__main__":

    source_acctid= sys.argv[1]

    target_acctid= sys.argv[2]

    money = sys.argv[3]

    conn = pymysql.connect('localhost', 'root', 'root', 'imooc', charset='utf8')

    tr_money = TransferMoney(conn)

    try:

        tr_money.transfer(source_acctid, target_acctid, money)

    except Exception as e:

        print("出现问题:", str(e))

    finally:

        conn.close()

 python bank_demo.py 3 1 1000

check_acct_available:select * from account where acctid=

check_acct_available:select * from account where acctid=

chas_enough_mone:select * from account where acctid= and money>

reduce_money:update account set money=money -  where acctid=

rad_money:update account set money=money +  where acctid=