Python sqlite3事务处理方法实例分析

本文实例讲述了Python sqlite3事务处理方法。分享给大家供大家参考，具体如下：

sqlite3事务总结:

在connect()中不传入 isolation_level

事务处理:

使用connection.commit()

#!/usr/bin/env python
# -*- coding:utf-8 -*-
'''sqlite3事务总结:
在connect()中不传入 isolation_level
事务处理:
 使用connection.commit()
分析:
 智能commit状态:
   生成方式: 在connect()中不传入 isolation_level, 此时isolation_level==''
     在进行 执行Data Modification Language (DML) 操作(INSERT/UPDATE/DELETE/REPLACE)时, 会自动打开一个事务,
     在执行 非DML, 非query (非 SELECT 和上面提到的)语句时, 会隐式执行commit
     可以使用 connection.commit()方法来进行提交
   注意:
     不能和cur.execute("COMMIT")共用
 自动commit状态:
   生成方式: 在connect()中传入 isolation_level=None
     这样,在任何DML操作时,都会自动提交
   事务处理
     connection.execute("BEGIN TRANSACTION")
     connection.execute("COMMIT")
   如果不使用事务, 批量添加数据非常缓慢
数据对比:
 两种方式, 事务耗时差别不大
 count = 100000
   智能commit即时提交耗时: 0.621
   自动commit耗时: 0.601
   智能commit即时提交耗时: 0.588
   自动commit耗时: 0.581
   智能commit即时提交耗时: 0.598
   自动commit耗时: 0.588
   智能commit即时提交耗时: 0.589
   自动commit耗时: 0.602
   智能commit即时提交耗时: 0.588
   自动commit耗时: 0.622
'''
import sys
import time
class Elapse_time(object):
 '''耗时统计工具'''
 def __init__(self, prompt=''):
   self.prompt = prompt
   self.start = time.time()
 def __del__(self):
   print('％s耗时: ％.3f' ％ (self.prompt, time.time() - self.start))
CElapseTime = Elapse_time
import sqlite3
# -------------------------------------------------------------------------------
# 测试
#
filename = 'e:/temp/a.db'
def prepare(isolation_level = ''):
 connection = sqlite3.connect(filename, isolation_level = isolation_level)
 connection.execute("create table IF NOT EXISTS people (num, age)")
 connection.execute('delete from people')
 connection.commit()
 return connection, connection.cursor()
def db_insert_values(cursor, count):
 num = 1
 age = 2 * num
 while num <= count:
   cursor.execute("insert into people values (?, ?)", (num, age))
   num += 1
   age = 2 * num
def study_case1_intelligent_commit(count):
 '''
 在智能commit状态下, 不能和cur.execute("COMMIT")共用
 '''
 connection, cursor = prepare()
 elapse_time = Elapse_time(' 智能commit')
 db_insert_values(cursor, count)
 #cursor.execute("COMMIT") #产生异常
 cursor.execute("select count(*) from people")
 print (cursor.fetchone())
def study_case2_autocommit(count):
 connection, cursor = prepare(isolation_level = None)
 elapse_time = Elapse_time(' 自动commit')
 db_insert_values(cursor, count)
 cursor.execute("select count(*) from people")
 print (cursor.fetchone())
def study_case3_intelligent_commit_manual(count):
 connection, cursor = prepare()
 elapse_time = Elapse_time(' 智能commit即时提交')
 db_insert_values(cursor, count)
 connection.commit()
 cursor.execute("select count(*) from people")
 print (cursor.fetchone())
def study_case4_autocommit_transaction(count):
 connection, cursor = prepare(isolation_level = None)
 elapse_time = Elapse_time(' 自动commit')
 connection.execute("BEGIN TRANSACTION;") # 关键点
 db_insert_values(cursor, count)
 connection.execute("COMMIT;") #关键点
 cursor.execute("select count(*) from people;")
 print (cursor.fetchone())
if __name__ == '__main__':
 count = 10000
 prepare()
 for i in range(5):
   #study_case1_intelligent_commit(count) #不提交数据
   #study_case2_autocommit(count) #非常缓慢
   study_case3_intelligent_commit_manual(count)
   study_case4_autocommit_transaction(count)

希望本文所述对大家Python程序设计有所帮助。