MySQL两个查询合并成一个结果
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
