mysql 查询合并
如果我们需要将两个select语句的结果作为一个整体显示出来,我们就需要用到union或者union all关键字。union(或称为联合)的作用是将多个结果合并在一起显示出来。
注意:两个列表中的字段要一样才可以合并(顺序也要一样)
满足条件:
1、两个select查询的列的数量必须相同;
2、每个列的数据类型需要相似;
1.先写两条select
第一条select:
select date_format(add_time, '%y-%m-%d') as 'add_time', count(add_time) as 'reach_intention' from table1 where ## where 条件可以根据自己实际情况来定 date_format(add_time, '%y-%m-%d') > date_format(date_sub(now(), interval 1 month), '%y-%m-%d') group by date_format(add_time, '%y-%m-%d')
这是查询出来的结果
第二条select:
select date_format(add_date, '%y-%m-%d') as 'add_time' , count(add_date) as 'post_release' from table2 where ## where 条件可以根据自己实际情况来定 date_format(add_date, '%y-%m-%d') > date_format(date_sub(now(), interval 1 month), '%y-%m-%d') group by date_format(add_date, '%y-%m-%d')
第二条select查询出来的结果
2.合并查询结果
先把两条select用union all连接起来
select date_format(add_time, '%y-%m-%d') as 'add_time', count(add_time) as 'reach_intention' , '' as 'post_release' from table1 where date_format(add_time, '%y-%m-%d') > date_format(date_sub(now(), interval 30 day), '%y-%m-%d') group by date_format(add_time, '%y-%m-%d') union all select date_format(add_date, '%y-%m-%d') as 'add_time' , '' as 'reach_intention' , count(add_date) as 'post_release' from table2 where date_format(add_date, '%y-%m-%d') > date_format(date_sub(now(), interval 30 day), '%y-%m-%d') group by date_format(add_date, '%y-%m-%d')
在外层嵌套一个select
## 括号里面放 用 union all 连接的select select * from () test ## 这里要给表起个别名 不然会报 every derived table must have its own alias 每个派生表都必须有自己的别名
把union all 连接的select 放到括号里面去然后运行
select * from ( select date_format(add_time, '%y-%m-%d') as 'add_time', count(add_time) as 'reach_intention' , '' as 'post_release' from table1 where date_format(add_time, '%y-%m-%d') > date_format(date_sub(now(), interval 30 day), '%y-%m-%d') group by date_format(add_time, '%y-%m-%d') union all select date_format(add_date, '%y-%m-%d') as 'add_time' , '' as 'reach_intention' , count(add_date) as 'post_release' from table2 where date_format(add_date, '%y-%m-%d') > date_format(date_sub(now(), interval 30 day), '%y-%m-%d') group by date_format(add_date, '%y-%m-%d') ) test
运行结果
把结果按日期分组排序。
使用 group by 和 order by 关键字
select add_time, sum(reach_intention) as 'reach_intention' , sum(post_release) as 'post_release' from ( select date_format(add_time, '%y-%m-%d') as 'add_time', count(add_time) as 'reach_intention' , '' as 'post_release' from table1 where date_format(add_time, '%y-%m-%d') > date_format(date_sub(now(), interval 30 day), '%y-%m-%d') group by date_format(add_time, '%y-%m-%d') union all select date_format(add_date, '%y-%m-%d') as 'add_time' , '' as 'reach_intention' , count(add_date) as 'post_release' from table2 where date_format(add_date, '%y-%m-%d') > date_format(date_sub(now(), interval 30 day), '%y-%m-%d') group by date_format(add_date, '%y-%m-%d') ) test group by test.add_time order by test.add_time desc
结果如下
总结
到此这篇关于mysql两个查询如何合并成一个结果的文章就介绍到这了,更多相关mysql两个查询合并一个内容请搜索<计算机技术网(www.ctvol.com)!!>以前的文章或继续浏览下面的相关文章希望大家以后多多支持<计算机技术网(www.ctvol.com)!!>!
需要了解更多数据库技术:MySQL两个查询如何合并成一个结果详解,都可以关注数据库技术分享栏目—计算机技术网(www.ctvol.com)!
本文来自网络收集,不代表计算机技术网立场,如涉及侵权请联系管理员删除。
ctvol管理联系方式QQ:251552304
本文章地址:https://www.ctvol.com/dtteaching/1234124.html