python mysql-connector模块连接数据库详解
1. 介绍
MySQL 是最流行的关系型数据库管理系统，mysql-connector 来连接使用 MySQL， mysql-connector 是 MySQL 官方提供的驱动器。
2. 安装
$ pip install mysql-connector
注意：如果你的 MySQL 是 8.0 版本，密码插件验证方式发生了变化，早期版本为 mysql_native_password，8.0 版本为 caching_sha2_password，所以需要做些改变：
先修改 my.ini 配置：
[mysqld]
default_authentication_plugin=mysql_native_password
然后在 mysql 下执行以下命令来修改密码：
ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY '新密码';
3. 用法
3.1 创建数据库连接
import mysql.connector
mydb = mysql.connector.connect(
host="192.168.1.190",
user="root",
passwd="Password01!"
)
print(mydb)
输出：
python my2.py
<mysql.connector.connection.MySQLConnection object at 0x7ff34aa24410>
3.2 创建数据库
import mysql.connector
mydb = mysql.connector.connect(
host="localhost",
user="root",
passwd="123456"
)
mycursor = mydb.cursor()
mycursor.execute("CREATE DATABASE runoob_db;")
3.3 查看数据库是否存在
import mysql.connector
mydb = mysql.connector.connect(
host="192.168.1.190",
user="root",
passwd="Password01!"
)
mycursor = mydb.cursor()
mycursor.execute("SHOW DATABASES;")
for x in mycursor:
print(x)
输出：
$ python my1.py
(u'information_schema',)
(u'api_server',)
(u'api_server_test',)
(u'horus',)
(u'mgm',)
(u'mysql',)
(u'mysqlmanager',)
(u'performance_schema',)
(u'redismanager',)
(u'sys',)
3.4 创建数据表
import mysql.connector
mydb = mysql.connector.connect(
host="localhost",
user="root",
passwd="123456",
database="runoob_db"
)
mycursor = mydb.cursor()
mycursor.execute("CREATE TABLE sites (name VARCHAR(255), url VARCHAR(255))")
3.5 查看数据表是否已存在
import mysql.connector
mydb = mysql.connector.connect(
host="localhost",
user="root",
passwd="123456",
database="runoob_db"
)
mycursor = mydb.cursor()
mycursor.execute("SHOW TABLES")
for x in mycursor:
print(x)
3.6 主键设置
给 sites 表添加主键
import mysql.connector
mydb = mysql.connector.connect(
host="localhost",
user="root",
passwd="123456",
database="runoob_db"
)
mycursor = mydb.cursor()
mycursor.execute("ALTER TABLE sites ADD COLUMN id INT AUTO_INCREMENT PRIMARY KEY")
给表创建主键
import mysql.connector
mydb = mysql.connector.connect(
host="localhost",
user="root",
passwd="123456",
database="runoob_db"
)
mycursor = mydb.cursor()
mycursor.execute("CREATE TABLE sites (id INT AUTO_INCREMENT PRIMARY KEY, name VARCHAR(255), url VARCHAR(255))")
3.7 插入数据
import mysql.connector
mydb = mysql.connector.connect(
host="localhost",
user="root",
passwd="123456",
database="runoob_db"
)
mycursor = mydb.cursor()
sql = "INSERT INTO sites (name, url) VALUES (%s, %s)"
val = ("RUNOOB", "https://www.runoob.com")
mycursor.execute(sql, val)
mydb.commit() # 数据表内容有更新，必须使用到该语句
print(mycursor.rowcount, "记录插入成功。")
3.8 批量插入
批量插入使用 executemany() 方法
import mysql.connector
mydb = mysql.connector.connect(
host="localhost",
user="root",
passwd="123456",
database="runoob_db"
)
mycursor = mydb.cursor()
sql = "INSERT INTO sites (name, url) VALUES (%s, %s)"
val = [
('Google', 'https://www.google.com'),
('Github', 'https://www.github.com'),
('Taobao', 'https://www.taobao.com'),
('stackoverflow', 'https://www.stackoverflow.com/')
]
mycursor.executemany(sql, val)
mydb.commit() # 数据表内容有更新，必须使用到该语句
print(mycursor.rowcount, "记录插入成功。")
print("1 条记录已插入, ID:", mycursor.lastrowid)
3.9 查询数据
3.9.1 获取所有记录
import mysql.connector
mydb = mysql.connector.connect(
host="localhost",
user="root",
passwd="123456",
database="runoob_db"
)
mycursor = mydb.cursor()
mycursor.execute("SELECT * FROM sites")
myresult = mycursor.fetchall() # fetchall() 获取所有记录
for x in myresult:
print(x)
输出：
(1, 'RUNOOB', 'https://www.runoob.com')
(2, 'Google', 'https://www.google.com')
(3, 'Github', 'https://www.github.com')
(4, 'Taobao', 'https://www.taobao.com')
(5, 'stackoverflow', 'https://www.stackoverflow.com/')
(6, 'Zhihu', 'https://www.zhihu.com')
3.9.2 只想读取一条数据，可以使用 fetchone() 方法
import mysql.connector
mydb = mysql.connector.connect(
host="localhost",
user="root",
passwd="123456",
database="runoob_db"
)
mycursor = mydb.cursor()
mycursor.execute("SELECT * FROM sites")
myresult = mycursor.fetchone()
print(myresult)
输出结果为：
(1, 'RUNOOB', 'https://www.runoob.com')
3.9.3 排序
查询结果排序可以使用 ORDER BY 语句，默认的排序方式为升序，关键字为 ASC，如果要设置降序排序，可以设置关键字 DESC。
import mysql.connector
mydb = mysql.connector.connect(
host="localhost",
user="root",
passwd="123456",
database="runoob_db"
)
mycursor = mydb.cursor()
sql = "SELECT * FROM sites ORDER BY name"
#sql = "SELECT * FROM sites ORDER BY name DESC" #降序
#mycursor.execute("SELECT * FROM sites LIMIT 3") #通过 "LIMIT" 语句设置查询的数据量
#mycursor.execute("SELECT * FROM sites LIMIT 3 OFFSET 1") 使用的关键字是 OFFSET指定起始位置
mycursor.execute(sql)
myresult = mycursor.fetchall()
for x in myresult:
print(x)
3.9.4 了防止数据库查询发生 SQL 注入的攻击，我们可以使用 %s 占位符来转义查询的条件。
升序
import mysql.connector
mydb = mysql.connector.connect(
host="localhost",
user="root",
passwd="123456",
database="runoob_db"
)
mycursor = mydb.cursor()
sql = "SELECT * FROM sites WHERE name = %s"
na = ("RUNOOB", )
mycursor.execute(sql, na)
myresult = mycursor.fetchall()
for x in myresult:
print(x)
输出结果为：
(3, 'Github', 'https://www.github.com')
(2, 'Google', 'https://www.google.com')
(1, 'RUNOOB', 'https://www.runoob.com')
(5, 'stackoverflow', 'https://www.stackoverflow.com/')
(4, 'Taobao', 'https://www.taobao.com')
(6, 'Zhihu', 'https://www.zhihu.com')
3.10 删除记录
import mysql.connector
mydb = mysql.connector.connect(
host="localhost",
user="root",
passwd="123456",
database="runoob_db"
)
mycursor = mydb.cursor()
sql = "DELETE FROM sites WHERE name = 'stackoverflow'"
mycursor.execute(sql)
mydb.commit()
print(mycursor.rowcount, " 条记录删除")
为了防止数据库查询发生 SQL 注入的攻击，我们可以使用 %s 占位符来转义删除语句的条件
import mysql.connector
mydb = mysql.connector.connect(
host="localhost",
user="root",
passwd="123456",
database="runoob_db"
)
mycursor = mydb.cursor()
sql = "DELETE FROM sites WHERE name = %s"
na = ("stackoverflow", )
mycursor.execute(sql, na)
mydb.commit()
print(mycursor.rowcount, " 条记录删除")
3.11 更新表数据
import mysql.connector
mydb = mysql.connector.connect(
host="localhost",
user="root",
passwd="123456",
database="runoob_db"
)
mycursor = mydb.cursor()
sql = "UPDATE sites SET name = 'ZH' WHERE name = 'Zhihu'"
mycursor.execute(sql)
mydb.commit()
print(mycursor.rowcount, " 条记录被修改")
输出结果为：
1 条记录被修改
为了防止数据库查询发生 SQL 注入的攻击，我们可以使用 %s 占位符来转义更新语句的条件
import mysql.connector
mydb = mysql.connector.connect(
host="localhost",
user="root",
passwd="123456",
database="runoob_db"
)
mycursor = mydb.cursor()
sql = "UPDATE sites SET name = %s WHERE name = %s"
val = ("Zhihu", "ZH")
mycursor.execute(sql, val)
mydb.commit()
print(mycursor.rowcount, " 条记录被修改")
输出结果为：
1 条记录被修改
3.12 删除表
import mysql.connector
mydb = mysql.connector.connect(
host="localhost",
user="root",
passwd="123456",
database="runoob_db"
)
mycursor = mydb.cursor()
sql = "DROP TABLE IF EXISTS sites" # 删除数据表 sites
mycursor.execute(sql)
参考资料：
https://www.runoob.com/python3/python-mysql-connector.html