在python3.x中，可以使用pymysql来MySQL数据库的连接，并实现数据库的各种操作，本次博客主要介绍了pymysql的安装和使用方法。
PyMySQL的安装
一、.windows上的安装方法：
在python3.6中，自带pip3，所以在python3中可以直接使用pip3去安装所需的模块：
pip3 install pymysql -i https://pypi.douban.com/simple
二、.linux下安装方法：
1.tar包下载及解压
下载tar包 wget https://pypi.python.org/packages/29/f8/919a28976bf0557b7819fd6935bfd839118aff913407ca58346e14fa6c86/PyMySQL-0.7.11.tar.gz#md5=167f28514f4c20cbc6b1ddf831ade772 解压并展开tar包 tar xf PyMySQL-0.7.11.tar.gz
2.安装
[root@localhost PyMySQL-0.7.11]# python36 setup.py install
数据库的连接
本次测试创建的数据及表：
#创建数据库及表，然后插入数据 mysql> create database dbforpymysql; mysql> create table userinfo(id int not null auto_increment primary key,username varchar(10),passwd varchar(10))engine=innodb default charset=utf8; mysql> insert into userinfo(username,passwd) values('frank','123'),('rose','321'),('jeff',666);mysql> select * from userinfo;
+----+----------+--------+
| id | username | passwd |
+----+----------+--------+
| 1 | frank | 123 |
| 2 | rose | 321 |
| 3 | jeff | 666 |
+----+----------+--------+
3 rows in set (0.00 sec)
连接数据库：
import pymysql#连接数据库
db = pymysql.connect("localhost","root","LBLB1212@@","dbforpymysql")#使用cursor()方法创建一个游标对象
cursor = db.cursor()#使用execute()方法执行SQL语句
cursor.execute("SELECT * FROM userinfo")#使用fetall()获取全部数据
data = cursor.fetchall()#打印获取到的数据
print(data)#关闭游标和数据库的连接
cursor.close()
db.close()#运行结果
((1, 'frank', '123'), (2, 'rose', '321'), (3, 'jeff', '666'))
要完成一个MySQL数据的连接，在connect中可以接受以下参数：
def __init__(self, host=None, user=None, password="", database=None, port=0, unix_socket=None, charset='', sql_mode=None, read_default_file=None, conv=None, use_unicode=None, client_flag=0, cursorclass=Cursor, init_command=None, connect_timeout=10, ssl=None, read_default_group=None, compress=None, named_pipe=None, no_delay=None, autocommit=False, db=None, passwd=None, local_infile=False, max_allowed_packet=16*1024*1024, defer_connect=False, auth_plugin_map={}, read_timeout=None, write_timeout=None, bind_address=None): 参数解释： host: Host where the database server is located #主机名或者主机地址 user: Username to log in as #用户名 password: Password to use. #密码 database: Database to use, None to not use a particular one. #指定的数据库 port: MySQL port to use, default is usually OK. (default: 3306) #端口，默认是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. #当客户端有多个网络接口的时候，指点连接到数据库的接口，可以是一个主机名或者ip地址 unix_socket: Optionally, you can use a unix socket rather than TCP/IP. charset: Charset you want to use. #指定字符编码 sql_mode: Default SQL_MODE to use. read_default_file: Specifies my.cnf file to read these parameters from under the [client] section. conv: Conversion dictionary to use instead of the default one. This is used to provide custom marshalling and unmarshaling of types. See converters. use_unicode: Whether or not to default to unicode strings. This option defaults to true for Py3k. client_flag: Custom flags to send to MySQL. Find potential values in constants.CLIENT. cursorclass: Custom cursor class to use. init_command: Initial SQL statement to run when connection is established. connect_timeout: Timeout before throwing an exception when connecting. (default: 10, min: 1, max: 31536000) ssl: A dict of arguments similar to mysql_ssl_set()'s parameters. For now the capath and cipher arguments are not supported. read_default_group: Group to read from in the configuration file. compress; Not supported named_pipe: Not supported autocommit: Autocommit mode. None means use server default. (default: False) local_infile: Boolean to enable the use of LOAD DATA LOCAL command. (default: False) max_allowed_packet: Max size of packet sent to server in bytes. (default: 16MB) Only used to limit size of "LOAD LOCAL INFILE" data packet smaller than default (16KB). defer_connect: Don't explicitly connect on contruction - wait for connect call. (default: False) auth_plugin_map: A dict of plugin names to a class that processes that plugin. The class will take the Connection object as the argument to the constructor. The class needs an authenticate method taking an authentication packet as an argument. For the dialog plugin, a prompt(echo, prompt) method can be used (if no authenticate method) for returning a string from the user. (experimental) db: Alias for database. (for compatibility to MySQLdb) passwd: Alias for password. (for compatibility to MySQLdb)
cursor其实是调用了cursors模块下的Cursor的类，这个模块主要的作用就是用来和数据库交互的，当你实例化了一个对象的时候，你就可以调用对象下面的各种绑定方法：
class Cursor(object): """ This is the object you use to interact with the database. """ def close(self): """ Closing a cursor just exhausts all remaining data. """ def setinputsizes(self, *args): """Does nothing, required by DB API."""<span style="color: #0000ff;">def</span> setoutputsizes(self, *<span style="color: #000000;">args): </span><span style="color: #800000;">"""</span><span style="color: #800000;">Does nothing, required by DB API.</span><span style="color: #800000;">"""</span> <span style="color: #0000ff;">def</span> execute(self, query, args=<span style="color: #000000;">None): </span><span style="color: #800000;">"""</span><span style="color: #800000;">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. </span><span style="color: #800000;">"""</span> <span style="color: #0000ff;">def</span><span style="color: #000000;"> executemany(self, query, args): </span><span style="color: #008000;">#</span><span style="color: #008000;"> type: (str, list) -> int</span> <span style="color: #800000;">"""</span><span style="color: #800000;">Run several data against one query :param query: query to execute on server :param args: Sequence of sequences or mappings. It is used as parameter. :return: Number of rows affected, if any. This method improves performance on multiple-row INSERT and REPLACE. Otherwise it is equivalent to looping over args with execute(). </span><span style="color: #800000;">"""</span> <span style="color: #0000ff;">def</span><span style="color: #000000;"> fetchone(self): </span><span style="color: #800000;">"""</span><span style="color: #800000;">Fetch the next row</span><span style="color: #800000;">"""</span> <span style="color: #0000ff;">def</span> fetchmany(self, size=<span style="color: #000000;">None): </span><span style="color: #800000;">"""</span><span style="color: #800000;">Fetch several rows</span><span style="color: #800000;">"""</span> <span style="color: #0000ff;">def</span><span style="color: #000000;"> fetchall(self): </span><span style="color: #800000;">"""</span><span style="color: #800000;">Fetch all the rows</span><span style="color: #800000;">"""</span><span style="color: #000000;"> ......</span></pre>