Python连接MySQL数据库之pymysql模块使用（1）

01Python登录.py

username = input("输入用户名：")
pwd = input("请输入密码：")

# if username == "erge" and pwd == "dashabi":
#     print("登陆成功！")
# else:
#     print("滚~")


with open("userinfo.txt", "r", encoding="utf-8") as f:
    for line in f:
        # print(line.strip())
        u, p = line.strip().split("|")
        if u == username and p == pwd:
            print("登陆成功！")
            break
    else:
        print("go out~")


02Python连接数据库登录.py

import pymysql

username = input("输入用户名：")
pwd = input("请输入密码：")

# if username == "erge" and pwd == "dashabi":
#     print("登陆成功！")
# else:
#     print("滚~")

# 拿到用户输入的用户名密码

# 去数据库里面判断用户名和密码是否正确
# 1. 连接数据库
conn = pymysql.connect(
    host="localhost",
    port=3306,  # 端口号是数字类型
    database="userinfo",  # 写自己本地的数据库名字
    user="root",
    password="123456",
    charset="utf8"   # 千万记得没有-
)

cursor = conn.cursor()  # 获取输入SQL语句的光标对象
sql = "select * from info;"
ret = cursor.execute(sql)
print(ret)
# 关闭连接
cursor.close()
conn.close()


# 2. 判断 --> 只需要把检索条件写到sql语句中，去数据库执行就可以了

# with open("userinfo.txt", "r", encoding="utf-8") as f:
#     for line in f:
#         # print(line.strip())
#         u, p = line.strip().split("|")
#         if u == username and p == pwd:
#             print("登陆成功！")
#             break
#     else:
#         print("go out~")


03登录校验MySQL.py

import pymysql

# 获取用户输入
username = input("输入用户名：")
pwd = input("请输入密码：")


# 连接数据库检索有没有该用户
conn = pymysql.connect(
    host="localhost",
    port=3306,
    database="userinfo",
    user="root",
    password="123456",
    charset="utf8"
)

cursor = conn.cursor()  # 获取光标
# 拼接要执行的SQL语句
sql = "select * from info where username='%s' and password='%s'" % (username, pwd)
print(sql)
print("=" * 120)
# 执行SQL语句
ret = cursor.execute(sql)
if ret:
    print("登录成功")
else:
    print("登录失败！")
# 关闭光标对像
cursor.close()
# 关闭连接
conn.close()

04登录校验MySQL规避SQL注入.py

import pymysql

# 获取用户输入
username = input("输入用户名：")
pwd = input("请输入密码：")


# 连接数据库检索有没有该用户
conn = pymysql.connect(
    host="localhost",
    port=3306,
    database="userinfo",
    user="root",
    password="123456",
    charset="utf8"
)

cursor = conn.cursor()  # 获取光标
# 拼接要执行的SQL语句
sql = 'select * from info where username=%s and password=%s'
print(sql)
print("=" * 120)
# 执行SQL语句
ret = cursor.execute(sql, [username, pwd])  # 让pymysql帮我们拼接SQL语句
if ret:
    print("登录成功")
else:
    print("登录失败！")
# 关闭光标对像
cursor.close()
# 关闭连接
conn.close()

05pymysql增操作.py

"""
pymysql增操作
"""

import pymysql

conn = pymysql.connect(
    host="localhost",
    port=3306,
    database="userinfo",
    user="root",
    password="123456",
    charset="utf8"
)

cursor = conn.cursor()

# 拼接语句
sql = "insert into info (username, password)VALUES (%s, %s)"
# 执行
try:
    cursor.execute(sql, ["大旭",])
    # 自己写个for循环 (今天作业自己试下)
    conn.commit()
except Exception as e:
    print("报错啦：",str(e))
    conn.rollback()  # 回滚
# 对数据库做写操作一定要记得提交assword

cursor.close()
conn.close()

06演示lastrowid有什么用.py

import pymysql

conn = pymysql.connect(
    host="localhost",
    port=3306,
    database="userinfo",
    user="root",
    password="123456",
    charset="utf8"
)

cursor = conn.cursor()
# 创建班级的sql语句
sql1 = "insert into class (name) VALUES (%s)"
# 创建学生的sql语句
sql2 = "insert into student (name, cid) VALUES (%s, %s)"


cursor.execute(sql1, "全栈9期")
new_id = cursor.lastrowid  # 获取刚插入数据的ID值
cursor.execute(sql2, ["小东北", new_id])

conn.commit()
cursor.close()
conn.close()

07批量插入数据.py

import pymysql

conn = pymysql.connect(
    host="localhost",
    port=3306,
    database="userinfo",
    user="root",
    password="123456",
    charset="utf8"
)

cursor = conn.cursor()
# 创建班级的sql语句
sql = "insert into info (username, password) VALUES (%s, %s)"

data = [("alex1", "dashabi"), ("污Sir1",), ("xiaoyima1", "nvshen")]
try:
    cursor.executemany(sql, data)  # 内部实现for循环，批量执行插入语句
    # for i in data:
    #     cursor.execute(sql, i)
    conn.commit()  # 提交一次
except Exception as e:
    print("错啦！")
    conn.rollback()

cursor.close()
conn.close()

08删除数据操作.py

import pymysql

conn = pymysql.connect(
    host="localhost",
    port=3306,
    database="userinfo",
    user="root",
    password="123456",
    charset="utf8"
)

cursor = conn.cursor()

# sql = "delete from info WHERE username=%s"
sql = "delete from info WHERE id=%s"

cursor.execute(sql,8)

conn.commit()
cursor.close()
conn.close()