https://blog.youkuaiyun.com/gycool21zh-cnhttps://blog.youkuaiyun.com/https://blog.youkuaiyun.com/gycool21/article/details/79955926https://blog.youkuaiyun.com/gycool21/article/details/79955926gycool21Mon, 16 Apr 2018 08:43:49 +0800https://blog.youkuaiyun.com/gycool21/article/details/79896732https://blog.youkuaiyun.com/gycool21/article/details/79896732gycool21Wed, 11 Apr 2018 14:55:29 +0800https://blog.youkuaiyun.com/gycool21/article/details/77461152https://blog.youkuaiyun.com/gycool21/article/details/77461152gycool21Mon, 21 Aug 2017 22:09:18 +0800https://blog.youkuaiyun.com/gycool21/article/details/77108370https://blog.youkuaiyun.com/gycool21/article/details/77108370gycool21Sat, 12 Aug 2017 21:25:27 +0800https://blog.youkuaiyun.com/gycool21/article/details/77074272https://blog.youkuaiyun.com/gycool21/article/details/77074272gycool21Thu, 10 Aug 2017 22:26:13 +0800https://blog.youkuaiyun.com/gycool21/article/details/76862316https://blog.youkuaiyun.com/gycool21/article/details/76862316gycool21Mon, 07 Aug 2017 22:26:28 +0800https://blog.youkuaiyun.com/gycool21/article/details/76560207https://blog.youkuaiyun.com/gycool21/article/details/76560207gycool21Tue, 01 Aug 2017 22:17:36 +0800https://blog.youkuaiyun.com/gycool21/article/details/72858576https://blog.youkuaiyun.com/gycool21/article/details/72858576gycool21Sun, 04 Jun 2017 13:39:57 +0800https://blog.youkuaiyun.com/gycool21/article/details/53080783https://blog.youkuaiyun.com/gycool21/article/details/53080783gycool21Tue, 08 Nov 2016 11:48:21 +0800https://blog.youkuaiyun.com/gycool21/article/details/52860133https://blog.youkuaiyun.com/gycool21/article/details/52860133gycool21Thu, 20 Oct 2016 13:37:18 +0800https://blog.youkuaiyun.com/gycool21/article/details/52849614https://blog.youkuaiyun.com/gycool21/article/details/52849614gycool21Wed, 19 Oct 2016 15:46:08 +0800https://blog.youkuaiyun.com/gycool21/article/details/52837553https://blog.youkuaiyun.com/gycool21/article/details/52837553gycool21Mon, 17 Oct 2016 11:52:33 +0800https://blog.youkuaiyun.com/gycool21/article/details/52808783https://blog.youkuaiyun.com/gycool21/article/details/52808783gycool21Thu, 13 Oct 2016 17:50:23 +0800操作符，否则将引擎放弃使用索引而进行全表扫描。2、对查询进行优化，应尽量避免全表扫描，首先应考虑在 where 及 order by 涉及的列上建立索引。3、应尽量避免在 where 子句中对字段进行 null 值判断，否则将导致引擎放弃使用索引而进行全表扫描，如：select id from t where num is null可以在num上设置]]>https://blog.youkuaiyun.com/gycool21/article/details/52798578https://blog.youkuaiyun.com/gycool21/article/details/52798578gycool21Thu, 13 Oct 2016 16:30:08 +0800https://blog.youkuaiyun.com/gycool21/article/details/52798485https://blog.youkuaiyun.com/gycool21/article/details/52798485gycool21Wed, 12 Oct 2016 16:52:42 +0800https://blog.youkuaiyun.com/gycool21/article/details/52769062https://blog.youkuaiyun.com/gycool21/article/details/52769062gycool21Wed, 12 Oct 2016 10:36:31 +0800https://blog.youkuaiyun.com/gycool21/article/details/52765305https://blog.youkuaiyun.com/gycool21/article/details/52765305gycool21Sun, 09 Oct 2016 16:08:07 +0800https://blog.youkuaiyun.com/gycool21/article/details/52754004https://blog.youkuaiyun.com/gycool21/article/details/52754004gycool21Sat, 08 Oct 2016 15:09:26 +0800https://blog.youkuaiyun.com/gycool21/article/details/52724946https://blog.youkuaiyun.com/gycool21/article/details/52724946gycool21Sun, 02 Oct 2016 23:31:03 +0800https://blog.youkuaiyun.com/gycool21/article/details/52679521https://blog.youkuaiyun.com/gycool21/article/details/52679521gycool21Tue, 27 Sep 2016 11:56:01 +0800