sql - MySQL 服务器已消失错误

Question

Warning: mysql_query() [function.mysql-query]: 
MySQL server has gone away in filename.php on line 201  

查询:

SELECT * FROM ta
    LEFT JOIN tb ON ta_id = tb_oid 
    LEFT JOIN tc ON ta_id = tc_oid 
    LEFT JOIN td ON ta_id = td_oid
WHERE 
    ta_time1 > 0 OR ta_time2 > 0 OR 
    tb_time1 > 0 OR tb_time2 > 0 OR 
    tc_time1 > 0 OR tc_time2 > 0 OR 
    td_time1 > 0 OR td_time2 > 0 
GROUP BY td_id 
ORDER BY  
    ta_time1 DESC, ta_time2 DESC,
    tb_time1 DESC, tb_time2 DESC,
    tc_time1 DESC, tc_time2 DESC,
    td_time1 DESC, td_time2 DESC
LIMIT 0, 40  

如何优化该查询？

Answer 1

• 为所有字段设置索引(如果您尚未这样做)。
• 尽可能使用小田地。例如。如果 ID 是 128 字节字符串，您可以在其中使用小型 int，请使用后者

顺便说一下，如果你不知道“has gone gone”是什么意思，请查看手册: http://dev.mysql.com/doc/refman/5.0/en/gone-away.html