pymysql.Connect()参数说明
host(str):      MySQL服务器地址
port(int):      MySQL服务器端口号
user(str):      用户名
passwd(str):    密码
db(str):        数据库名称
charset(str):   连接编码

connection对象支持的方法
cursor()        使用该连接创建并返回游标
commit()        提交当前事务
rollback()      回滚当前事务
close()         关闭连接

cursor对象支持的方法
execute(op)     执行一个数据库的查询命令
fetchone()      取得结果集的下一行
fetchmany(size) 获取结果集的下几行
fetchall()      获取结果集中的所有行
rowcount()      返回数据条数或影响行数
close()         关闭游标对象

import pymysql.cursors

# 连接数据库
connect = pymysql.Connect(
    host=‘localhost‘,
    port=3310,
    user=‘woider‘,
    passwd=‘3243‘,
    db=‘python‘,
    charset=‘utf8‘
)

# 获取游标
cursor = connect.cursor()

# 插入数据
sql = "INSERT INTO trade (name, account, saving) VALUES ( ‘%s‘, ‘%s‘, %.2f )"
data = (‘雷军‘, ‘13512345678‘, 10000)
cursor.execute(sql % data)
connect.commit()
print(‘成功插入‘, cursor.rowcount, ‘条数据‘)

# 修改数据
sql = "UPDATE trade SET saving = %.2f WHERE account = ‘%s‘ "
data = (8888, ‘13512345678‘)
cursor.execute(sql % data)
connect.commit()
print(‘成功修改‘, cursor.rowcount, ‘条数据‘)

# 查询数据
sql = "SELECT name,saving FROM trade WHERE account = ‘%s‘ "
data = (‘13512345678‘,)
cursor.execute(sql % data)
for row in cursor.fetchall():
    print("Name:%s\tSaving:%.2f" % row)
print(‘共查找出‘, cursor.rowcount, ‘条数据‘)

# 删除数据
sql = "DELETE FROM trade WHERE account = ‘%s‘ LIMIT %d"
data = (‘13512345678‘, 1)
cursor.execute(sql % data)
connect.commit()
print(‘成功删除‘, cursor.rowcount, ‘条数据‘)

# 事务处理
sql_1 = "UPDATE trade SET saving = saving + 1000 WHERE account = ‘18012345678‘ "
sql_2 = "UPDATE trade SET expend = expend + 1000 WHERE account = ‘18012345678‘ "
sql_3 = "UPDATE trade SET income = income + 2000 WHERE account = ‘18012345678‘ "

try:
    cursor.execute(sql_1)  # 储蓄增加1000
    cursor.execute(sql_2)  # 支出增加1000
    cursor.execute(sql_3)  # 收入增加2000
except Exception as e:
    connect.rollback()  # 事务回滚
    print(‘事务处理失败‘, e)
else:
    connect.commit()  # 事务提交
    print(‘事务处理成功‘, cursor.rowcount)

# 关闭连接
cursor.close()
connect.close()