python 实现mysql 查询

要想使Python可以操作MySQL数据库，首先需要安装MySQL-python包，在CentOS上可以使用一下命令来安装

$ sudo yum install MySQL-python

啥都不说了，走两步吧，下面的程序创建了一个到mysql数据库的连接，然后执行了一个简单的查询，并打印查询结果

import MySQLdb

conn = MySQLdb.connect (host = "172.17.23.121", user = "fkong", passwd = "fkong", db = "fkong")
cursor = conn.cursor ()
cursor.execute ("SELECT VERSION()")
row = cursor.fetchone ()
print "MySQL server version:", row[0]
cursor.close ()
conn.close ()

下面看一个数据库建表和插入操作

import MySQLdb

conn = MySQLdb.connect (host = "172.17.23.121", user = "fkong", passwd = "fkong", db = "fkong")
cursor = conn.cursor ()

cursor.execute ("""
CREATE TABLE TEST
(
ID INT,
COL1 VARCHAR(40),
COL2 VARCHAR(40),
COL3 VARCHAR(40)
)
""")

cursor.execute ("""
INSERT INTO TEST (ID, COL1, COL2, COL3)
VALUES
(1, 'a', 'b', 'c'),
(2, 'aa', 'bb', 'cc'),
(3, 'aaa', 'bbb', 'ccc')
""")

conn.commit()
cursor.close ()
conn.close ()

下面再来看看查询，查询通常有两种方式：一种是使用cursor.fetchall（）获取所有查询结果，然后再一行一行的迭代；另一种每次通过cursor.fetchone()获取一条记录，直到获取的结果为空为止。看一下下面的例子：

import MySQLdb

conn = MySQLdb.connect (host = "172.17.23.121", user = "fkong", passwd = "fkong", db = "fkong")
cursor = conn.cursor ()

cursor.execute ("SELECT * FROM TEST")
rows = cursor.fetchall()
for row in rows:
print "%d, %s, %s, %s" % (row[0], row[1], row[2], row[3])

print "Number of rows returned: %d" % cursor.rowcount

cursor.execute ("SELECT * FROM TEST")
while (True):
row = cursor.fetchone()
if row == None:
break
print "%d, %s, %s, %s" % (row[0], row[1], row[2], row[3])

print "Number of rows returned: %d" % cursor.rowcount

cursor.close ()
conn.close ()