python连接MySQL

    再python3中连接mysql的模块位pymysql，我们可以通过pip来安装：

pip install pymysql

这样我们就可以使用该模块连接mysql了。

连接mysql用到pymysql的Connect()模块，

Connect(*args, **kwargs)  #Connect方法
    Establish a connection to the MySQL database. Accepts several
    arguments:

    host: Host where the database server is located
    user: Username to log in as
    password: Password to use.
    database: Database to use, None to not use a particular one.
    port: MySQL port to use, default is usually OK. (default: 3306)
    bind_address: When the client has multiple network interfaces, specify the interface from which to connect to the host. Argument can be a hostname or an IP address.
    unix_socket: Optionally, you can use a unix socket rather than TCP/IP.
    charset: Charset you want to use.

连接数据库后需要设置游标（cursor）进行数据库的执行操作conn.cursor():

>>> help(conn.cursor) #创建游标
Help on method cursor in module pymysql.connections:

cursor(cursor=None) method of pymysql.connections.Connection instance
    Create a new cursor to execute queries with

设置了cursor后，就可以写sql语句，使用cursor的实例去执行了,执行用到execute()方法：

>>> help(cursor.execute)   #execute方法
Help on method execute in module pymysql.cursors:

execute(query, args=None) method of pymysql.cursors.Cursor instance
    Execute a query

    :param str query: Query to execute.

    :param args: parameters used with query. (optional)
    :type args: tuple, list or dict

    :return: Number of affected rows
    :rtype: int

    If args is a list or tuple, %s can be used as a placeholder in the query.
    If args is a dict, %(name)s can be used as a placeholder in the query.

执行sql语句后，查询返回的结果，可以使用cursor的fetchall()函数查看，这会返回一个元组，每个元组的元素还是一个元组cursor.fetchall()：

>>> help(cursor.fetchall)
Help on method fetchall in module pymysql.cursors:

fetchall() method of pymysql.cursors.Cursor instance
    Fetch all the rows

可以使用for循环逐个查看结果。

下面是一个完整的例子：

import pymysql

conn=pymysql.Connect(host='192.168.37.130',port=3306,user='root',password='123456',database='user')
cursor=conn.cursor(pymysql.cursors.DictCursor)
sql='select * from users'
res_num=cursor.execute(sql)
print(res_num)
res_content=cursor.fetchall()
for i in res_content:
    print(i)

 

上面模拟了一个简单的数据库查询操作。下面我们在写一个简单的例子：

import pymysql

conn=pymysql.Connect(host='192.168.37.130',port=3306,user='root',password='123456',database='user')
cursor=conn.cursor(pymysql.cursors.DictCursor)
name=input('Input name:').strip()
sql='select * from users where name like %s'
res_num=cursor.execute(sql,name )
if res_num>0:
    res_content=cursor.fetchall()
    for i in res_content:
        print(i)
else:
    print('Not in database')