Python 操做 MySQL 的正確姿式

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做者 |邵建永
編輯 | 顧鄉mysql

使用Python進行MySQL的庫主要有三個,Python-MySQL(更熟悉的名字多是MySQLdb),PyMySQL和SQLAlchemy。sql

Python-MySQL資格最老,核心由C語言打造,接口精煉,性能最棒,缺點是環境依賴較多,安裝複雜,近兩年已中止更新,只支持Python2,不支持Python3。數據庫

PyMySQL爲替代Python-MySQL而生,純python打造,接口與Python-MySQL兼容,安裝方便,支持Python3。編程

SQLAlchemy是一個ORM框架,它並不提供底層的數據庫操做,而是要藉助於MySQLdb、PyMySQL等第三方庫來完成,目前SQLAlchemy在Web編程領域應用普遍。api

本文主要介紹PyMySQL的正確使用方法,示例代碼都是選自實戰項目。框架

安裝

簡單的方式:性能

pip install pymysql

若是沒法聯網,須要進行離線安裝,例如:fetch

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

導入

import pymysql

鏈接

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

查詢

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.execute(sql_str)
    rows = cur.fetchall()
    cur.close()
    con.close()

    assert len(rows) == 1, 'Fatal error: country_code does not exists!'
    return rows[0][0]

簡單插入

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)
            assert cur.rowcount == 1, 'Fatal error: The wx-refund record be deleted!'

            sql_str = ("UPDATE t_wxrefund_trans"
                        + " SET Fcheck_amount_flag=1"
                        + ", Fmodify_time=now()"
                        + " WHERE Fremit_id='%s'" % remit_id
            logging.info(sql_str)
            cur.execute(sql_str)

            assert cur.rowcount == 1, 'The number of affected rows not equal to 1'
            con.commit()
        except:
            con.rollback()
            logging.exception('Update operation error')
            raise
        finally:
            cur.close()
            con.close()

PyMySQL已經至關成熟,和Python-MySQL同樣,它在不少Linux發行版本中都是可選的安裝組件。code


原文連接:https://www.qcloud.com/community/article/687813

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