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HomeBackend DevelopmentPython TutorialExplanation of basic operation examples of SQLite3 in Python

Explanation of basic operation examples of SQLite3 in Python

Aug 15, 2017 pm 03:09 PM
pythonsqlite3Basic operations

这篇文章主要介绍了Python2.7编程中SQLite3基本操作方法,涉及Python2.7操作sqlite3数据库的增删改查及防注入等相关技巧,需要的朋友可以参考下

本文实例讲述了Python2.7中SQLite3基本操作方法。分享给大家供大家参考,具体如下:

1、基本操作


# -*- coding: utf-8 -*-
#!/usr/bin/env python
import sqlite3
def mykey(x):
  return x[3]
conn=sqlite3.connect("D:\\demo\\my_db.db")
sql = "CREATE TABLE IF NOT EXISTS mytb ( a char , b int , c real, d DATE)"
# a char , b int , c real 表示该表有三个字段,
# a 是字符串类型, b 是整数类型, c 是实数类型。
conn.execute( sql )
cs = conn.cursor()
#cs.execute("DELETE FROM mytb WHERE A='张三' ")
cs.execute("DELETE FROM mytb  ")
#删除所有记录
'''''
cs.execute( "INSERT INTO mytb ( a,b,c,d ) values('Zhang San',25, 120, '2014-03-04')" )
cs.execute( "INSERT INTO mytb ( a,b,c,d ) values( 'Wang Wu',24, 110, '2014-05-01')" )
cs.execute( "INSERT INTO mytb ( a,b,c,d ) values( 'Li Si',23, 130, '2014-04-06')" )
'''
#批量注入,batchdata是一个列表,列表里每一个元素都是一个元组
batchdata=[('Zhang San',25, 120, '2014-03-04'),
      ( 'Wang Wu',24, 110, '2014-05-01'),
      ( 'Li Si',23, 130, '2014-04-06')]
cs.executemany('INSERT INTO mytb values (?,?,?,?)',batchdata)
conn.commit() #将加入的记录保存到磁盘,非常重要!
cs.execute("SELECT name, sql FROM sqlite_master WHERE type='table'")
recs = cs.fetchall( )
print ( recs )
cs.execute( "SELECT * FROM mytb ")#打开数据表
recs = cs.fetchall()#取出所有记录
print ( "there is ", len(recs)," notes." )
print recs
recs.sort(key = mykey)
print recs
cs.close()
conn.close()

2、删除一条记录,使用sql字符串变量可以实现带参数的删除


sql="DELETE FROM my_table WHERE number='" + my_num + "'"
cs.execute(sql)

3、查询某一条或多条记录

如果SQLite3查找的数据库记录中含有中文,取出到Python时要对数据进行decode处理。当时我上网查的时候说要用GBK解码,但我自己却解码失败了,换成utf-8解码才成功显示。 另外,如果只查询一条可以用fetchone语句,或者fetchall之后再通过python把它找出来。


sql="SELECT name FROM my_table WHERE number ='" + my_num + "'"
cs.execute(sql)
the_name=(cs.fetchall())[0][0].decode('utf-8')

4、避免重复注入

有时候我们会有重复的记录,为了避免把相同的记录多次插入到数据库,可以使用如下语句:


sql="INSERT OR REPLACE INTO "+my_table+" values (?,?,?,?,?,?,?) "
#假设my_table有7项

5、插入中文记录至SQLite3

Python是unicode编码,但数据库对中文是使用GBK编码,比如stock_name变量含有中文,则需要做unicode(name, "gbk")处理


batch=[(stock_num, unicode(stock_name, "gbk") )]
cs.executemany( "INSERT OR REPLACE INTO my_table values (?,?) ",batch)

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