一、介紹
之前我們都是通過MySQL自帶的命令行客戶端工具mysql來操作數據庫，那如何在python程序中操作數據庫呢？
這就用到了pymysql模塊，該模塊本質就是一個套接字客戶端軟件，使用前需要事先安裝。
pip install -i http://mirrors.aliyun.com/pypi/simple --trusted-host mirrors.aliyun.com pymysql
二、鏈接、執行SQL、關閉鏈接
import pymysql
# 建立鏈接
conn = pymysql.connect(host="localhost", user="root", password="20001001", database="db", charset="utf8")
# 初始化遊標
cursor = conn.cursor()
# 執行SQL語句
name = input("Please input name: ").strip()
sql = 'select * from employee where name = "%s";' % name
print("sql: ", sql)
res = cursor.execute(sql)
print("res: ", res)
cursor.close()
conn.close()
執行結果爲：
Please input name: alex
sql: select * from employee where name = "alex"
res: 1
三、execute()之sql注入
SQL語句的註釋符號爲：–
因此註釋之後的所有語句都不會執行。
#1、sql注入之：用戶存在，繞過密碼
alex' -- 任意字符
#2、sql注入之：用戶不存在，繞過用戶與密碼
xxx' or 1=1 -- 任意字符
pymysql其實已經幫我們做好了這方面的防護，使用execute幫助我們拼接SQL語句更加安全。
sql="select * from userinfo where name=%s and password=%s" # 注意%s需要去掉引號，因爲pymysql會自動爲我們加上
res=cursor.execute(sql,[user,pwd]) # pymysql模塊自動幫我們解決sql注入的問題，只要我們按照pymysql的規矩來。
四、pymysql增刪改查
import pymysql
conn = pymysql.connect(host="localhost", user="root", password="20001001", database="db")
cursor = conn.cursor()
# 增
sql1 = 'insert into employee (name, sex, age, dep_id) values(%s, %s, %s, %s);'
res1 = cursor.execute(sql1, ("Alex", "male", 19, 200))
print("res1: ", res1)
res2 = cursor.executemany(sql1, [("Coco", "female", 19, 201), ("Bei", "female", 5, 202)])
print("res2: ", res2)
print(cursor.lastrowid) # 獲取插入的最後一條數據的自增ID
# 刪
sql2 = "delete from employee where name = %s;"
res2 = cursor.execute(sql2, "alex")
print("res3: ", res2)
# 改
sql3 = "update employee set age = 2 where name = %s;"
res3 = cursor.execute(sql3, "Bei")
print("res3: ", res3)
# 查
sql4 = "select * from employee;"
res4 = cursor.execute(sql4)
print("res41: ", cursor.fetchone(), end="\n\n")
print("res42: ", cursor.fetchmany(2), end="\n\n")
print("res43: ", cursor.fetchall(), end="\n\n")
conn.commit() # 提交後才發現表中插入記錄成功
cursor.close()
conn.close()
執行結果爲：
res1: 1
res2: 2
8
res3: 2
res3: 1
res41: (1, 'egon', 'male', 18, 200)
res42: ((3, 'wupeiqi', 'male', 38, 201), (4, 'yuanhao', 'female', 28, 202))
res43: ((5, 'liwenzhou', 'male', 18, 200), (6, 'jingliyang', 'female', 18, 204), (8, 'Coco', 'female', 19, 201), (9, 'Bei', 'female', 2, 202))
Process finished with exit code 0
數據庫結果：
