python 操作 MySql 数据库

准备工作 :

安装 pymysql

• 命令：pip install pymysql

重要函数

函数	说明
connect	创建链接
cursor	创建一个游标
commit	事务提交，如果没有设为自动提交，则每次操作后必须提交事务，否则操作无效。
rollback	操作出错时，可以用这个函数回滚到执行事务之前
close	关闭连接

 

创建链接：

conn = pymysql.connect(host="localhost",
                           db="test",
                           user="root",
                           password="",
                           port=3306,
                           charset="utf8"
                           )

向数据库中添加一条信息：

cursor = conn.cursor()
sql_insert = "INSERT  INTO book(name,price) VALUES ('hhh', 7)"
try:
    cursor.execute(sql_insert)
    conn.commit()
except Exception as e:
    conn.rollback()
conn.close()

表结构如下：

connect参数：

    self,
    host=None,          # 要连接的主机地址
    user=None,          # 用于登录的数据库用户
    password='',        # 密码
    database=None,      # 要连接的数据库
    port=0,             # 端口，一般为 3306
    unix_socket=None,   # 选择是否要用unix_socket而不是TCP/IP
    charset='',         # 字符编码
    sql_mode=None,      # Default SQL_MODE to use.
    read_default_file=None, # 从默认配置文件(my.ini或my.cnf)中读取参数
    conv=None,          # 转换字典
    use_unicode=None,   # 是否使用 unicode 编码
    client_flag=0,      # Custom flags to send to MySQL. Find potential values in constants.CLIENT.
    cursorclass=<class 'pymysql.cursors.Cursor'>, # 选择 Cursor 类型
    init_command=None,  # 连接建立时运行的初始语句 
    connect_timeout=10, # 连接超时时间，(default: 10, min: 1, max: 31536000)
    ssl=None,           # A dict of arguments similar to mysql_ssl_set()'s parameters.For now the capath and cipher arguments are not supported. 
    read_default_group=None, # Group to read from in the configuration file.
    compress=None,      # 不支持
    named_pipe=None,    # 不支持
    no_delay=None,      # 
    autocommit=False,   # 是否自动提交事务
    db=None,            # 同 database，为了兼容 MySQLdb
    passwd=None,        # 同 password，为了兼容 MySQLdb
    local_infile=False, # 是否允许载入本地文件
    max_allowed_packet=16777216, # 限制 `LOCAL DATA INFILE` 大小
    defer_connect=False, # Don't explicitly connect on contruction - wait for connect call.
    auth_plugin_map={}, #
    read_timeout=None,  # 
    write_timeout=None, 
    bind_address=None   # 当客户有多个网络接口，指定一个连接到主机

完整代码：

import pymysql

def getConnection():
    conn = pymysql.connect(host="localhost",
                           db="test",
                           user="root",
                           password="",
                           port=3306,
                           charset="utf8"
                           )
    return conn

def Insert():
    conn = getConnection()
    cursor = conn.cursor()
    sql_insert = "INSERT  INTO book(name,price) VALUES ('hhh', 7)"
    try:
        cursor.execute(sql_insert)
        conn.commit()
    except Exception as e:
        conn.rollback()
    conn.close()

def Delete():
    conn = getConnection()
    cursor = conn.cursor()
    sql_delete = "DELETE FROM book WHERE NAME = %s"
    try:
        cursor.execute(sql_delete, ("hhh", ))
        conn.commit()
    except Exception as e:
        conn.rollback()
    conn.close()

def Update():
    coon = getConnection()
    cursor = coon.cursor()
    update_delete = "UPDATE book SET NAME = %s WHERE NAME = 'test2'"
    try:
        cursor.execute(update_delete, ("update",))
        coon.commit()
    except Exception as e:
        coon.rollback()
    coon.close()

def Select():
    coon = getConnection()
    cursor = coon.cursor()
    sql = "SELECT * FROM book WHERE name = %s"
    try:
        count = cursor.execute(sql, ("TEST",))
    except Exception as e:

        coon.rollback()
    print(count)

#Insert()
#Select()
#Delete()
Update()