转载 Python 操作 MySQL 的正确姿势 - 琉璃块 Python 操作 MySQL 的正确姿势

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作者 |邵建永
编辑 | 顾乡

使用Python进行MySQL的库主要有三个，Python-MySQL（更熟悉的名字可能是MySQLdb），PyMySQL和SQLAlchemy。

Python-MySQL资格最老，核心由C语言打造，接口精炼，性能最棒，缺点是环境依赖较多，安装复杂，近两年已停止更新，只支持Python2，不支持Python3。

PyMySQL为替代Python-MySQL而生，纯python打造，接口与Python-MySQL兼容，安装方便，支持Python3。

SQLAlchemy是一个ORM框架，它并不提供底层的数据库操作，而是要借助于MySQLdb、PyMySQL等第三方库来完成，目前SQLAlchemy在Web编程领域应用广泛。

本文主要介绍PyMySQL的正确使用方法，示例代码都是选自实战项目。

安装

简单的方式：

pip install pymysql

如果无法联网，需要进行离线安装，例如：

pip install pymysql-x.x.x.tar.gz

导入

import pymysql

连接

def connect_wxremit_db():
    return pymysql.connect(host=\'10.123.5.28\',
                           port=3306,
                           user=\'root\',
                           password=\'root1234\',
                           database=\'db_name\',
                           charset=\'latin1\')

查询

def query_country_name(cc2):
    sql_str = ("SELECT Fcountry_name_zh"
                + " FROM t_country_code"
                + " WHERE Fcountry_2code=\'%s\'" % (cc2))
    logging.info(sql_str)
con = mysql_api.connect_wxremit_db()
cur = con.cursor()
cur.<span class="hljs-built_in">execute</span>(sql_str)
rows = cur.fetchall()
cur.<span class="hljs-built_in">close</span>()
con.<span class="hljs-built_in">close</span>()

<span class="hljs-built_in">assert</span> <span class="hljs-built_in">len</span>(rows) == <span class="hljs-number">1</span>, <span class="hljs-string">\'Fatal error: country_code does not exists!\'</span>
<span class="hljs-keyword">return</span> rows[<span class="hljs-number">0</span>][<span class="hljs-number">0</span>]

简单插入

def insert_file_rec(self, file_name, file_md5):
        con = mysql_api.connect_wxremit_db()
        cur = con.cursor()
        try:
            sql_str = ("INSERT INTO t_forward_file (Ffile_name, Ffile_md5)", 
                       + " VALUES (\'%s\', \'%s\')" % (file_name, file_md5))
            cur.execute(sql_str)
            con.commit()
        except:
            con.rollback()
            logging.exception(\'Insert operation error\')
            raise
        finally:
            cur.close()
            con.close()

批量插入

remit_ids = [(\'1234\', \'CAD\'), (\'5678\', \'HKD\')]
con = mysql_api.connect_wxremit_db()

cur = con.cursor()
try:

cur.executemany("INSERT INTO t_order (Fremit_id, Fcur_type, Fcreate_time"

+ " VALUES (%s, %s, now())", new_items)
assert cur.rowcount == len(remit_ids), \'my error message\'

con.commit()
except Exception as e:

con.rollback()

logging.exception(\'Insert operation error\')
finally:

cur.close()

con.close()

更新

    def update_refund_trans(self, remit_id):
        con = mysql_api.connect_wxremit_db()
        cur = con.cursor()
        try:
            sql_str = ("SELECT Fremit_id"
                       + " FROM t_wxrefund_trans"
                       + " WHERE Fremit_id=\'%s\'" % remit_id
                       + " FOR UPDATE")
            logging.info(sql_str)
        cur.execute(sql_str)
        <span class="hljs-keyword">assert</span> cur.rowcount == <span class="hljs-number">1</span>, <span class="hljs-string">\'Fatal error: The wx-refund record be deleted!\'</span>

        sql_str = (<span class="hljs-string">"UPDATE t_wxrefund_trans"</span>
                    + <span class="hljs-string">" SET Fcheck_amount_flag=1"</span>
                    + <span class="hljs-string">", Fmodify_time=now()"</span>
                    + <span class="hljs-string">" WHERE Fremit_id=\'%s\'"</span> % remit_id
        logging.info(sql_str)
        cur.execute(sql_str)

        <span class="hljs-keyword">assert</span> cur.rowcount == <span class="hljs-number">1</span>, <span class="hljs-string">\'The number of affected rows not equal to 1\'</span>
        con.commit()
    <span class="hljs-keyword">except</span>:
        con.rollback()
        logging.exception(<span class="hljs-string">\'Update operation error\'</span>)
        <span class="hljs-keyword">raise</span>
    <span class="hljs-keyword">finally</span>:
        cur.close()
        con.close()

PyMySQL已经相当成熟，和Python-MySQL一样，它在很多Linux发行版本中都是可选的安装组件。

原文链接：https://www.qcloud.com/community/article/687813

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	<div class="postDesc">posted @ <span id="post-date">2017-04-25 21:26</span> <a href="https://www.cnblogs.com/liuliliuli2017/">琉璃块</a> 阅读(<span id="post_view_count">12782</span>) 评论(<span id="post_comment_count">0</span>)  <a href="https://i.cnblogs.com/EditPosts.aspx?postid=6763988" rel="nofollow">编辑</a> <a href="#" onclick="AddToWz(6763988);return false;">收藏</a></div>
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