Question

我正在使用MySQLdb（http://mysql-python.sourceforge.net/）。似乎connection.open和connection.sqlstate（）对我不起作用。以下是代码：

def open(self):
    #TODO: check the connection's status
    # self.__conn.open OR self.__conn.sqlstate()
    try:
        print "sqlstate:"+str( self.__conn.sqlstate() )
        print "open?"+str( self.__conn.open )
        return "00000" == self.__conn.sqlstate()
    except Exception as e:
        print "Exception while checking MYSQL Connection:"+str(e) 
        return False

但是当我运行＆＃34; sudo service mysql stop;睡60; sudo服务mysql启动;＆＃34;做测试。输出如下。似乎以下的输出重复了一次（我终于杀死了这个过程）。当服务器关闭时，connection.open为1，connection.sqlstate（）为00000.但是当服务器启动时，connection.executemany（）仍会抛出异常。有任何想法吗？感谢。

...
    2015-10-20 14:09:06 Exception while executing statement:(2006, 'MySQL server has gone away')
    2015-10-20 14:09:06 sqlstate:00000
    2015-10-20 14:09:06 open?1
    2015-10-20 14:09:06 Reconnected to MYSQL.
    2015-10-20 14:09:06 Exception while executing statement:(2006, 'MySQL server has gone away')
    2015-10-20 14:09:06 sqlstate:00000
    2015-10-20 14:09:06 open?1
    2015-10-20 14:09:06 Reconnected to MYSQL.
    2015-10-20 14:09:06 Exception while executing statement:(2006, 'MySQL server has gone away')
    2015-10-20 14:09:06 sqlstate:00000
    2015-10-20 14:09:06 open?1
    2015-10-20 14:09:06 Reconnected to MYSQL.
    2015-10-20 14:09:06 Exception while executing statement:(2006, 'MySQL server has gone away')
    2015-10-20 14:09:06 sqlstate:00000
    2015-10-20 14:09:06 open?1
...

更新

我再次测试了。输出如下。每次睡眠都是10秒。输出正常，但即使服务器关闭，connection.open也是1。但是connection.sqlstate（）是对的（HY000）。

 2015-10-20 14:35:56 Exception while executing statement:(2006, 'MySQL server has gone away')
2015-10-20 14:35:56 Exception while ping:(2003, "Can't connect to MySQL server on '10.1.1.25' (111)")
2015-10-20 14:35:56 sqlstate:HY000
2015-10-20 14:35:56 open?1
2015-10-20 14:35:56 sleeping...
2015-10-20 14:36:06 Exception while ping:(2003, "Can't connect to MySQL server on '10.1.1.25' (111)")
2015-10-20 14:36:06 sqlstate:HY000
2015-10-20 14:36:06 open?1
2015-10-20 14:36:06 sleeping...
2015-10-20 14:36:16 Exception while ping:(2003, "Can't connect to MySQL server on '10.1.1.25' (111)")
2015-10-20 14:36:16 sqlstate:HY000
2015-10-20 14:36:16 open?1
2015-10-20 14:36:16 sleeping...
2015-10-20 14:36:26 Exception while ping:(2003, "Can't connect to MySQL server on '10.1.1.25' (111)")
2015-10-20 14:36:26 sqlstate:HY000
2015-10-20 14:36:26 open?1
2015-10-20 14:36:26 sleeping...
2015-10-20 14:36:36 Exception while ping:(2003, "Can't connect to MySQL server on '10.1.1.25' (111)")
2015-10-20 14:36:36 sqlstate:HY000
2015-10-20 14:36:36 open?1
2015-10-20 14:36:36 sleeping...
2015-10-20 14:36:46 Exception while ping:(2003, "Can't connect to MySQL server on '10.1.1.25' (111)")
2015-10-20 14:36:46 sqlstate:HY000
2015-10-20 14:36:46 open?1
2015-10-20 14:36:46 sleeping...
2015-10-20 14:36:56 Exception while ping:(2003, "Can't connect to MySQL server on '10.1.1.25' (111)")
2015-10-20 14:36:56 sqlstate:HY000
2015-10-20 14:36:56 open?1
2015-10-20 14:36:56 sleeping...
2015-10-20 14:37:06 sqlstate:00000
2015-10-20 14:37:06 open?1
2015-10-20 14:37:06 Reconnected to MYSQL.

Answer 1

试试这个 -

import MySQLdb

def main():
  # Connect to the MySQL database
  db = MySQLdb.connect(host = 'z.cs.utexas.edu', user = 'userName', passwd = 'password', db = 'dbName')

  # Check if connection was successful
  if (db):
    # Carry out normal procedure
    print "Connection successful"
  else:
    # Terminate
    print "Connection unsuccessful"

Answer 2

我一直在寻找这个解决方案，但我找不到一个优雅的解决方案。

似乎没有直接的方式来做到这一点。如果您尝试执行查询，则只会发现您的连接已关闭。

我最终做了类似于这个答案的事情： How to check the connection alive in python?

Answer 3

你应该像这样编码：在每次执行之前，ping mysql-server，例如

import MySQLdb as db
    class DB(object):
        def __init__(self):
            try:
                self.conn =mdb.connect(host='***',port=3306,user='',passwd='')
            if (self.conn):
                INFO_LOG("DB init success")
            else:
                INFO_LOG("DB init fail")
            self.conn.autocommit(True)
            self.conn.select_db(DB_NAME)
            self.cursor = self.conn.cursor()
        except Exception as e:
            CRITICAL_LOG("DB init fail %s " % str(e))
    def insert(self,player_id,cmd):
        try:
            if self.conn is None:
                self.__init__()
            else:
                self.conn.ping(True)
            self.cursor.execute('INSERT INTO table values("%s",%s")' %
            (player_id,cmd))
        except Exception as e:
            import traceback
            traceback.print_exc()
            #error ocurs,rollback
            self.conn.rollback()

Answer 4

以防万一有人觉得有帮助：

import socket
import time
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
while sock.connect_ex(('db', 3306)) != 0: # 'db' is the host, 3306 is the port
    print('MySQL is not ready yet.')
    time.sleep(2)
sock.close()
print("Now it's up and running! Bye!")

Answer 5

您可以使用此库python-mysql的 is_connected 方法检查连接：

cnx = connector.connect(user="user",password="pass",host="host",database="database")

if (cnx.is_connected()):
    print("Connected")
else:
    print("Not connected")

如何检查Python中的MySQL连接是否已打开？

5 个答案: