group by having
2012-11-21 16:19
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group by 其实就是为了将本字段的内容进行分组,我用的数据库是mysql它有自己的分组方式,可以选择按字段内容的一部分进行分组。
先写个例子吧:
select count(`name`) as cu,`id`,`name` from admin group by `name` having `id`>60 order by cu DESC;
上面实现的查询就是把name进行分组看一样的有几个,把一样的名字出现次数按由大到小的次序并且是id大于60的数据,展示出id,name两个字段的信息
as是起别名的意思此时cu就是name的个数,group by是对name字段进行分组看相同名字的出现次数。
先写个例子吧:
select count(`name`) as cu,`id`,`name` from admin group by `name` having `id`>60 order by cu DESC;
上面实现的查询就是把name进行分组看一样的有几个,把一样的名字出现次数按由大到小的次序并且是id大于60的数据,展示出id,name两个字段的信息
as是起别名的意思此时cu就是name的个数,group by是对name字段进行分组看相同名字的出现次数。
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