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查看“Python MySQL - mysql-connector 驱动”的源代码
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{{DISPLAYTITLE:Python3 MySQL(mysql-connector)}}[[Category:Python 教程|36]] = Python MySQL - mysql-connector 驱动 = MySQL 是最流行的关系型数据库管理系统,如果你不熟悉 MySQL,可以阅读我们的 [[mysql tutorial|MySQL 教程。]] 本章节我们为大家介绍使用 '''mysql-connector''' 来连接使用 MySQL, '''mysql-connector''' 是 '''MySQL''' 官方提供的驱动器。 我们可以使用 '''pip''' 命令来安装 '''mysql-connector''': <sample title="" desc="" lang="python" hererun="1"> python -m pip install mysql-connector </sample> 使用以下代码测试 mysql-connector 是否安装成功: == demo_mysql_test.py: == <sample title="" desc="" lang="python" hererun="1"> import mysql.connector </sample> 执行以上代码,如果没有产生错误,表明安装成功。 <blockquote>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: <sample title="" desc="" lang="python" hererun="1"> [mysqld] default_authentication_plugin=mysql_native_password </sample> 然后在 mysql 下执行以下命令来修改密码: <sample title="" desc="" lang="python" hererun="1"> ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY '新密码'; </sample> 更多内容可以参考:[https://www.xiaobai.wang/note/45833 Python MySQL8.0 链接问题]。 </blockquote> == 创建数据库连接 == 可以使用以下代码来连接数据库: == demo_mysql_test.py: == <sample title="" desc="" lang="python" hererun="1"> import mysql.connector mydb = mysql.connector.connect( host="localhost", # 数据库主机地址 user="yourusername", # 数据库用户名 passwd="yourpassword" # 数据库密码 ) print(mydb) </sample> === 创建数据库 === 创建数据库使用 "CREATE DATABASE" 语句,以下创建一个名为 xiaobai_db 的数据库: == demo_mysql_test.py: == <sample title="" desc="" lang="python" hererun="1"> import mysql.connector mydb = mysql.connector.connect( host="localhost", user="root", passwd="123456" ) mycursor = mydb.cursor() mycursor.execute("CREATE DATABASE xiaobai_db") </sample> 创建数据库前我们也可以使用 "SHOW DATABASES" 语句来查看数据库是否存在: == demo_mysql_test.py: == 输出所有数据库列表: <sample title="" desc="" lang="python" hererun="1"> import mysql.connector mydb = mysql.connector.connect( host="localhost", user="root", passwd="123456" ) mycursor = mydb.cursor() mycursor.execute("SHOW DATABASES") for x in mycursor: print(x) </sample> 或者我们可以直接连接数据库,如果数据库不存在,会输出错误信息: == demo_mysql_test.py: == <sample title="" desc="" lang="python" hererun="1"> import mysql.connector mydb = mysql.connector.connect( host="localhost", user="root", passwd="123456", database="xiaobai_db" ) </sample> == 创建数据表 == 创建数据表使用 '''"CREATE TABLE"''' 语句,创建数据表前,需要确保数据库已存在,以下创建一个名为 '''sites''' 的数据表: == demo_mysql_test.py: == <sample title="" desc="" lang="python" hererun="1"> import mysql.connector mydb = mysql.connector.connect( host="localhost", user="root", passwd="123456", database="xiaobai_db" ) mycursor = mydb.cursor() mycursor.execute("CREATE TABLE sites (name VARCHAR(255), url VARCHAR(255))") </sample> 执行成功后,我们可以看到数据库创建的数据表 sites,字段为 name 和 url。 '''我们也可以使用 '''"SHOW TABLES"''' 语句来查看数据表是否已存在:''' == demo_mysql_test.py: == <sample title="" desc="" lang="python" hererun="1"> import mysql.connector mydb = mysql.connector.connect( host="localhost", user="root", passwd="123456", database="xiaobai_db" ) mycursor = mydb.cursor() mycursor.execute("SHOW TABLES") for x in mycursor: print(x) </sample> === 主键设置 === 创建表的时候我们一般都会设置一个主键(PRIMARY KEY),我们可以使用 '''"INT AUTO_INCREMENT PRIMARY KEY"''' 语句来创建一个主键,主键起始值为 1,逐步递增。 如果我们的表已经创建,我们需要使用 '''ALTER TABLE''' 来给表添加主键: == demo_mysql_test.py: == 给 sites 表添加主键。 <sample title="" desc="" lang="python" hererun="1"> import mysql.connector mydb = mysql.connector.connect( host="localhost", user="root", passwd="123456", database="xiaobai_db" ) mycursor = mydb.cursor() mycursor.execute("ALTER TABLE sites ADD COLUMN id INT AUTO_INCREMENT PRIMARY KEY") </sample> 如果你还未创建 sites 表,可以直接使用以下代码创建。 == demo_mysql_test.py: == 给表创建主键。 <sample title="" desc="" lang="python" hererun="1"> import mysql.connector mydb = mysql.connector.connect( host="localhost", user="root", passwd="123456", database="xiaobai_db" ) mycursor = mydb.cursor() mycursor.execute("CREATE TABLE sites (id INT AUTO_INCREMENT PRIMARY KEY, name VARCHAR(255), url VARCHAR(255))") </sample> == 插入数据 == 插入数据使用 '''"INSERT INTO"''' 语句: == demo_mysql_test.py: == 向 sites 表插入一条记录。 <sample title="" desc="" lang="python" hererun="1"> import mysql.connector mydb = mysql.connector.connect( host="localhost", user="root", passwd="123456", database="xiaobai_db" ) mycursor = mydb.cursor() sql = "INSERT INTO sites (name, url) VALUES (%s, %s)" val = ("XiaoBai.Wang", "https://www.xiaobai.wang") 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。") </sample> 执行代码,输出结果为: <sample title="" desc="" lang="python" hererun="1"> 1 记录插入成功 </sample> === 批量插入 === 批量插入使用 '''executemany()''' 方法,该方法的第二个参数是一个元组列表,包含了我们要插入的数据: == demo_mysql_test.py: == 向 sites 表插入多条记录。 <sample title="" desc="" lang="python" hererun="1"> import mysql.connector mydb = mysql.connector.connect( host="localhost", user="root", passwd="123456", database="xiaobai_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。") </sample> 执行代码,输出结果为: <sample title="" desc="" lang="python" hererun="1"> 4 记录插入成功。 </sample> 执行以上代码后,我们可以看看数据表的记录: 如果我们想在数据记录插入后,获取该记录的 ID ,可以使用以下代码: == demo_mysql_test.py: == <sample title="" desc="" lang="python" hererun="1"> import mysql.connector mydb = mysql.connector.connect( host="localhost", user="root", passwd="123456", database="xiaobai_db" ) mycursor = mydb.cursor() sql = "INSERT INTO sites (name, url) VALUES (%s, %s)" val = ("Zhihu", "https://www.zhihu.com") mycursor.execute(sql, val) mydb.commit() print("1 条记录已插入, ID:", mycursor.lastrowid) </sample> 执行代码,输出结果为: <sample title="" desc="" lang="python" hererun="1"> 1 条记录已插入, ID: 6 </sample> == 查询数据 == 查询数据使用 '''SELECT''' 语句: == demo_mysql_test.py: == <sample title="" desc="" lang="python" hererun="1"> import mysql.connector mydb = mysql.connector.connect( host="localhost", user="root", passwd="123456", database="xiaobai_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) </sample> 执行代码,输出结果为: <sample title="" desc="" lang="python" hererun="1"> (1, 'XiaoBai.Wang', 'https://www.xiaobai.wang') (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') </sample> 也可以读取指定的字段数据: == demo_mysql_test.py: == <sample title="" desc="" lang="python" hererun="1"> import mysql.connector mydb = mysql.connector.connect( host="localhost", user="root", passwd="123456", database="xiaobai_db" ) mycursor = mydb.cursor() mycursor.execute("SELECT name, url FROM sites") myresult = mycursor.fetchall() for x in myresult: print(x) </sample> 执行代码,输出结果为: <sample title="" desc="" lang="python" hererun="1"> ('XiaoBai.Wang', 'https://www.xiaobai.wang') ('Google', 'https://www.google.com') ('Github', 'https://www.github.com') ('Taobao', 'https://www.taobao.com') ('stackoverflow', 'https://www.stackoverflow.com/') ('Zhihu', 'https://www.zhihu.com') </sample> 如果我们只想读取一条数据,可以使用 '''fetchone()''' 方法: == demo_mysql_test.py: == <sample title="" desc="" lang="python" hererun="1"> import mysql.connector mydb = mysql.connector.connect( host="localhost", user="root", passwd="123456", database="xiaobai_db" ) mycursor = mydb.cursor() mycursor.execute("SELECT * FROM sites") myresult = mycursor.fetchone() print(myresult) </sample> 执行代码,输出结果为: <sample title="" desc="" lang="python" hererun="1"> (1, 'XiaoBai.Wang', 'https://www.xiaobai.wang') </sample> === where 条件语句 === 如果我们要读取指定条件的数据,可以使用 '''where''' 语句: == demo_mysql_test.py == 读取 name 字段为 XiaoBai.Wang 的记录: <sample title="" desc="" lang="python" hererun="1"> import mysql.connector mydb = mysql.connector.connect( host="localhost", user="root", passwd="123456", database="xiaobai_db" ) mycursor = mydb.cursor() sql = "SELECT * FROM sites WHERE name ='XiaoBai.Wang'" mycursor.execute(sql) myresult = mycursor.fetchall() for x in myresult: print(x) </sample> 执行代码,输出结果为: <sample title="" desc="" lang="python" hererun="1"> (1, 'XiaoBai.Wang', 'https://www.xiaobai.wang') </sample> 也可以使用通配符 %: == demo_mysql_test.py == <sample title="" desc="" lang="python" hererun="1"> import mysql.connector mydb = mysql.connector.connect( host="localhost", user="root", passwd="123456", database="xiaobai_db" ) mycursor = mydb.cursor() sql = "SELECT * FROM sites WHERE url LIKE '%oo%'" mycursor.execute(sql) myresult = mycursor.fetchall() for x in myresult: print(x) </sample> 执行代码,输出结果为: <sample title="" desc="" lang="python" hererun="1"> (1, 'XiaoBai.Wang', 'https://www.xiaobai.wang') (2, 'Google', 'https://www.google.com') </sample> 为了防止数据库查询发生 SQL 注入的攻击,我们可以使用 %s 占位符来转义查询的条件: == demo_mysql_test.py == <sample title="" desc="" lang="python" hererun="1"> import mysql.connector mydb = mysql.connector.connect( host="localhost", user="root", passwd="123456", database="xiaobai_db" ) mycursor = mydb.cursor() sql = "SELECT * FROM sites WHERE name = %s" na = ("XiaoBai.Wang", ) mycursor.execute(sql, na) myresult = mycursor.fetchall() for x in myresult: print(x) </sample> === 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'''。 == demo_mysql_test.py == 按 name 字段字母的升序排序: <sample title="" desc="" lang="python" hererun="1"> import mysql.connector mydb = mysql.connector.connect( host="localhost", user="root", passwd="123456", database="xiaobai_db" ) mycursor = mydb.cursor() sql = "SELECT * FROM sites ORDER BY name" mycursor.execute(sql) myresult = mycursor.fetchall() for x in myresult: print(x) </sample> 执行代码,输出结果为: <sample title="" desc="" lang="python" hererun="1"> (3, 'Github', 'https://www.github.com') (2, 'Google', 'https://www.google.com') (1, 'XiaoBai.Wang', 'https://www.xiaobai.wang') (5, 'stackoverflow', 'https://www.stackoverflow.com/') (4, 'Taobao', 'https://www.taobao.com') (6, 'Zhihu', 'https://www.zhihu.com') </sample> 降序排序实例: == demo_mysql_test.py == 按 name 字段字母的降序排序: <sample title="" desc="" lang="python" hererun="1"> import mysql.connector mydb = mysql.connector.connect( host="localhost", user="root", passwd="123456", database="xiaobai_db" ) mycursor = mydb.cursor() sql = "SELECT * FROM sites ORDER BY name DESC" mycursor.execute(sql) myresult = mycursor.fetchall() for x in myresult: print(x) </sample> 执行代码,输出结果为: <sample title="" desc="" lang="python" hererun="1"> (6, 'Zhihu', 'https://www.zhihu.com') (4, 'Taobao', 'https://www.taobao.com') (5, 'stackoverflow', 'https://www.stackoverflow.com/') (1, 'XiaoBai.Wang', 'https://www.xiaobai.wang') (2, 'Google', 'https://www.google.com') (3, 'Github', 'https://www.github.com') </sample> === Limit === 如果我们要设置查询的数据量,可以通过 '''"LIMIT"''' 语句来指定 == demo_mysql_test.py == 读取前 3 条记录: <sample title="" desc="" lang="python" hererun="1"> import mysql.connector mydb = mysql.connector.connect( host="localhost", user="root", passwd="123456", database="xiaobai_db" ) mycursor = mydb.cursor() mycursor.execute("SELECT * FROM sites LIMIT 3") myresult = mycursor.fetchall() for x in myresult: print(x) </sample> 执行代码,输出结果为: <sample title="" desc="" lang="python" hererun="1"> (1, 'XiaoBai.Wang', 'https://www.xiaobai.wang') (2, 'Google', 'https://www.google.com') (3, 'Github', 'https://www.github.com') </sample> 也可以指定起始位置,使用的关键字是 '''OFFSET''': == demo_mysql_test.py == 从第二条开始读取前 3 条记录: <sample title="" desc="" lang="python" hererun="1"> import mysql.connector mydb = mysql.connector.connect( host="localhost", user="root", passwd="123456", database="xiaobai_db" ) mycursor = mydb.cursor() mycursor.execute("SELECT * FROM sites LIMIT 3 OFFSET 1") # 0 为 第一条,1 为第二条,以此类推 myresult = mycursor.fetchall() for x in myresult: print(x) </sample> 执行代码,输出结果为: <sample title="" desc="" lang="python" hererun="1"> (2, 'Google', 'https://www.google.com') (3, 'Github', 'https://www.github.com') (4, 'Taobao', 'https://www.taobao.com') </sample> == 删除记录 == 删除记录使用 '''"DELETE FROM"''' 语句: == demo_mysql_test.py == 删除 name 为 stackoverflow 的记录: <sample title="" desc="" lang="python" hererun="1"> import mysql.connector mydb = mysql.connector.connect( host="localhost", user="root", passwd="123456", database="xiaobai_db" ) mycursor = mydb.cursor() sql = "DELETE FROM sites WHERE name = 'stackoverflow'" mycursor.execute(sql) mydb.commit() print(mycursor.rowcount, " 条记录删除") </sample> 执行代码,输出结果为: <sample title="" desc="" lang="python" hererun="1"> 1 条记录删除 </sample> '''注意:'''要慎重使用删除语句,删除语句要确保指定了 WHERE 条件语句,否则会导致整表数据被删除。 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: == demo_mysql_test.py == <sample title="" desc="" lang="python" hererun="1"> import mysql.connector mydb = mysql.connector.connect( host="localhost", user="root", passwd="123456", database="xiaobai_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") </sample> 执行代码,输出结果为: <sample title="" desc="" lang="python" hererun="1"> 1 条记录删除 </sample> == 更新表数据 == 数据表更新使用 '''"UPDATE"''' 语句: == demo_mysql_test.py == 将 name 为 Zhihu 的字段数据改为 ZH: <sample title="" desc="" lang="python" hererun="1"> import mysql.connector mydb = mysql.connector.connect( host="localhost", user="root", passwd="123456", database="xiaobai_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") </sample> 执行代码,输出结果为: <sample title="" desc="" lang="python" hererun="1"> 1 条记录被修改 </sample> '''注意:'''UPDATE 语句要确保指定了 WHERE 条件语句,否则会导致整表数据被更新。 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: == demo_mysql_test.py == <sample title="" desc="" lang="python" hererun="1"> import mysql.connector mydb = mysql.connector.connect( host="localhost", user="root", passwd="123456", database="xiaobai_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") </sample> 执行代码,输出结果为: <sample title="" desc="" lang="python" hererun="1"> 1 条记录被修改 </sample> == 删除表 == 删除表使用 '''"DROP TABLE"''' 语句, IF EXISTS 关键字是用于判断表是否存在,只有在存在的情况才删除: == demo_mysql_test.py == <sample title="" desc="" lang="python" hererun="1"> import mysql.connector mydb = mysql.connector.connect( host="localhost", user="root", passwd="123456", database="xiaobai_db" ) mycursor = mydb.cursor() sql = "DROP TABLE IF EXISTS sites" # 删除数据表 sites mycursor.execute(sql) </sample>
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