python操作SQLite
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。
#!/usr/bin/python
import sqlite3
conn = sqlite3.connect('test.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 test.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：
$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：
#!/usr/bin/python
import sqlite3
conn = sqlite3.connect('test.db')
print "Opened database successfully"
c = conn.cursor()
c.execute('''CREATE TABLE COMPANY
(ID INT PRIMARY KEY NOT NULL,
NAME TEXT NOT NULL,
AGE INT NOT NULL,
ADDRESS CHAR(50),
SALARY REAL);''')
print "Table created successfully"
conn.commit()
conn.close()
上述程序执行时，它会在 test.db 中创建 COMPANY 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 COMPANY 表中创建记录：
#!/usr/bin/python
import sqlite3
conn = sqlite3.connect('test.db')
c = conn.cursor()
print "Opened database successfully"
c.execute("INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) \
VALUES (1, 'Paul', 32, 'California', 20000.00 )")
c.execute("INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) \
VALUES (2, 'Allen', 25, 'Texas', 15000.00 )")
c.execute("INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) \
VALUES (3, 'Teddy', 23, 'Norway', 20000.00 )")
c.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 COMPANY 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 COMPANY 表中获取并显示记录：
#!/usr/bin/python
import sqlite3
conn = sqlite3.connect('test.db')
c = conn.cursor()
print "Opened database successfully"
cursor = c.execute("SELECT id, name, address, salary from COMPANY")
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：
#!/usr/bin/python
import sqlite3
conn = sqlite3.connect('test.db')
c = conn.cursor()
print "Opened database successfully"
c.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 COMPANY")
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
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：
#!/usr/bin/python
import sqlite3
conn = sqlite3.connect('test.db')
c = conn.cursor()
print "Opened database successfully"
c.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 COMPANY")
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
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