脚本之家,脚本语言编程技术及教程分享平台!
分类导航

Python|VBS|Ruby|Lua|perl|VBA|Golang|PowerShell|Erlang|autoit|Dos|bat|

服务器之家 - 脚本之家 - Python - Python SQLite3简介

Python SQLite3简介

2021-01-16 00:39MTbaby Python

这篇文章主要为大家详细介绍了Python SQLite3的简单介绍以及使用方法,具有一定的参考价值,感兴趣的小伙伴们可以参考一下

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。

?
1
2
3
4
5
#-*- 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:

?
1
2
3
$chmod +x sqlite.py
$./sqlite.py
Open database successfully

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:

?
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
#-*- 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:

?
1
2
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:

 

?
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
#-*- 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,NAME,AGE,ADDRESS,SALARY) \
   VALUES (2, 'Allen', 25, 'Texas', 15000.00 )");
 
conn.execute("INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) \
   VALUES (3, 'Teddy', 23, 'Norway', 20000.00 )");
 
conn.execute("INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) \
   VALUES (4, 'Mark', 25, '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:

?
1
2
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:

?
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
#-*- 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:

?
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
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:

?
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
#-*- 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, 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:

?
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
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:

?
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
#-*- 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 :", conn.total_changes
 
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:

?
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
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服务器之家。

原文链接:http://blog.csdn.net/mtbaby/article/details/58599741

延伸 · 阅读

精彩推荐