pymysql的使用2

import pymysql
#不要把自己的py文件起名叫pymysql。。
#否则会报错


conn = pymysql.connect(
    host = "localhost",
    user = "root",
    password = "",
    database = "s23",
    port = 3306,
    charset = 'utf8'
)
print(conn)
#cursor 游标对象
cur = conn.cursor()

# 防止sql注入，sql语句里面的参数不用加" "
user = input('请输入要查询的用户名')
pwd = input('请输入密码')
sql = 'select * from user where username = %s and pwd = %s'
# %s不用加"",也不用自己拼接了
print(sql)
retnum = cur.execute(sql,[user,pwd])
# 把需要的参数写在execute里[user,pwd]
print(retnum)#受影响的行数
cur.close()
conn.close()

if retnum:
    print('登录成功')
else:
    print('登录失败')

# 防止sql注入

#增加，删除，修改之后要commit
# 否则修改不生效
#见3