最近需要用Python写一个简易通讯录,但是对于数据存储很发愁。大家都知道,使用 Python 中的列表和字典进行存储数据是很不靠谱的,所以就想到Python有没有内置的数据库模块。
sqlite3简介
sqlite3 可使用 sqlite3 模块与 Python 进行集成。sqlite3 模块是由 Gerhard Haring 编写的。它提供了一个与 PEP 249 描述的 DB-API 2.0 规范兼容的 sql 接口。您不需要单独安装该模块,因为 Python 2.5.x 以上版本默认自带了该模块。
为了使用 sqlite3 模块,您首先必须创建一个表示数据库的连接对象,然后您可以有选择地创建光标对象,这将帮助您执行所有的 sql 语句。
怎么样,听起来不错吧!那就快来学习使用吧。
连接数据库
下面的 Python 代码显示了如何连接到一个现有的数据库。如果数据库不存在,那么它就会被创建,最后将返回一个数据库对象。
#-*- coding:utf-8 -*- import sqlite3 conn = sqlite3.connect('MysqL_person.db') print "Opened database successfully";
在这里,您也可以把数据库名称复制为特定的名称 :memory:,这样就会在 RAM 中创建一个数据库。现在,让我们来运行上面的程序,在当前目录中创建我们的数据库 MysqL_person.db。您可以根据需要改变路径。保存上面代码到 sqlite.py 文件中,并按如下所示执行。如果数据库成功创建,那么会显示下面所示的消息:
创建表
下面的 Python 代码段将用于在先前创建的数据库中创建一个表:
#-*- coding:utf-8 -*- import sqlite3 conn = sqlite3.connect('MysqL_person.db') print "Opened database successfully"; conn.execute('''CREATE TABLE MT (ID INT PRIMARY KEY NOT NULL,NAME TEXT NOT NULL,AGE INT NOT NULL,ADDRESS CHAR(50),SALARY REAL);''') print "Table created successfully"; conn.close()
上述程序执行时,它会在 test.db 中创建 MT 表,并显示下面所示的消息:
Opened database successfully Table created successfully
INSERT 操作
下面的 Python 程序显示了如何在上面创建的 MT 表中创建记录:
#-*- coding:utf-8 -*- import sqlite3 conn = sqlite3.connect('MysqL_person.db') print "Opened database successfully"; conn.execute("INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) \ VALUES (1,'Paul',32,'California',20000.00 )"); conn.execute("INSERT INTO COMPANY (ID,SALARY) \ VALUES (2,'Allen',25,'Texas',15000.00 )"); conn.execute("INSERT INTO COMPANY (ID,SALARY) \ VALUES (3,'Teddy',23,'norway',SALARY) \ VALUES (4,'Mark','Rich-Mond ',65000.00 )"); conn.commit() print "Records created successfully"; conn.close()
上述程序执行时,它会在 MT 表中创建给定记录,并会显示以下两行:
Opened database successfully Records created successfully
SELECT 操作
下面的 Python 程序显示了如何从前面创建的 MT 表中获取并显示记录:
#-*- coding:utf-8 -*- import sqlite3 conn = sqlite3.connect('MysqL_person.db') print "Opened database successfully"; cursor = conn.execute("SELECT id,name,address,salary from MT") for row in cursor: print "ID = ",row[0] print "NAME = ",row[1] print "ADDRESS = ",row[2] print "SALARY = ",row[3],"\n" print "Operation done successfully"; conn.close()
上述程序执行时,它会产生以下结果:
Opened database successfully ID = 1 NAME = Paul ADDRESS = California SALARY = 20000.0 ID = 2 NAME = Allen ADDRESS = Texas SALARY = 15000.0 ID = 3 NAME = Teddy ADDRESS = norway SALARY = 20000.0 ID = 4 NAME = Mark ADDRESS = Rich-Mond SALARY = 65000.0 Operation done successfully
UPDATE 操作
下面的 Python 代码显示了如何使用 UPDATE 语句来更新任何记录,然后从 COMPANY 表中获取并显示更新的记录:
#-*- coding:utf-8 -*- import sqlite3 conn = sqlite3.connect('MysqL_person.db') print "Opened database successfully"; conn.execute("UPDATE COMPANY set SALARY = 25000.00 where ID=1") conn.commit() print "Total number of rows updated :",conn.total_changes cursor = conn.execute("SELECT id,"\n" print "Operation done successfully"; conn.close()
上述程序执行时,它会产生以下结果:
Opened database successfully Total number of rows updated : 1 ID = 1 NAME = Paul ADDRESS = California SALARY = 25000.0 ID = 2 NAME = Allen ADDRESS = Texas SALARY = 15000.0 ID = 3 NAME = Teddy ADDRESS = norway SALARY = 20000.0 ID = 4 NAME = Mark ADDRESS = Rich-Mond SALARY = 65000.0 Operation done successfully
DELETE 操作
下面的 Python 代码显示了如何使用 DELETE 语句删除任何记录,然后从 COMPANY 表中获取并显示剩余的记录:
#-*- coding:utf-8 -*- import sqlite3 conn = sqlite3.connect('MysqL_person.db') print "Opened database successfully"; conn.execute("DELETE from COMPANY where ID=2;") conn.commit() print "Total number of rows deleted :",salary from MT") for row in cursor: print "ID = ",row[0] print "NAME = ",row[1] print "ADDRESS = ",row[2] print "SALARY = ","\n" print "Operation done successfully"; conn.close()
上述程序执行时,它会产生以下结果:
Opened database successfully Total number of rows deleted : 1 ID = 1 NAME = Paul ADDRESS = California SALARY = 20000.0 ID = 3 NAME = Teddy ADDRESS = norway SALARY = 20000.0 ID = 4 NAME = Mark ADDRESS = Rich-Mond SALARY = 65000.0 Operation done successfully
以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持编程小技巧。
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