将 2 个 SQL SELECT 结果合并为一个查询

Question

我想知道是否有办法将两个或多个结果集合并为一个。 我有以下两个查询 第一个查询：

SELECT
  CONCAT(day(db.prod_id.created_on),"-",month(db.prod_id.created_on),"-",year(db.prod_id.created_on)) as day_month_year,
  db.country.country ,
  count(concat(day(db.prod_id.created_on),"-",month(db.prod_id.created_on),"-",year(db.prod_id.created_on))) as count ,
  COUNT(DISTINCT db.prod_id.email) AS MAIL
from db.prod_id
left join db.country on db.prod_id.branch_id = db.country.id
where  db.prod_id.created_on > '2020-11-17'  and (db.country.type = 1 or db.country.type = 2)
group by
  concat(day(db.prod_id.created_on),"-",month(db.prod_id.created_on),"-",year(db.prod_id.created_on)),
  db.country.country
order by db.prod_id.created_on

第二个查询：

select
  CONCAT(day(db.prod_id.created_on),"-",month(db.prod_id.created_on),"-",year(db.prod_id.created_on)) as day_month_year,
  db.country.country,
  count(CONCAT(day(db.prod_id.created_on),"-",month(db.prod_id.created_on),"-",year(db.prod_id.created_on))) as count_BUY
from db.prod_id
left join db.prod_evaluations on db.prod_id.id = db.prod_evaluations.id
left join db.country on db.prod_id.branch_id = db.country.id
left join (Select prod_properties.prod_id, prod_properties.value From prod_properties Where prod_properties.property_id = 5) as db3 on db3.prod_id = db.prod_id.id
where db.prod_id.created_on > '2020-11-17'
and db3.value  = 'online-buy' and db.prod_id.status_id <> 25
group by
  concat(day(db.prod_id.created_on),"-",month(db.prod_id.created_on),"-",year(db.prod_id.created_on)),
  db.country.country
order by db.prod_id.created_on

第一个查询给出以下结果：

+------------+---------+-------+------+
|    day     | Country | Count | Mail |
+------------+---------+-------+------+
| 17-11-2020 | IT      |   200 |  100 |
| 17-11-2020 | US      |   250 |  100 |
| 18-11-2020 | IT      |   350 |  300 |
| 18-11-2020 | US      |   200 |  100 |
+------------+---------+-------+------+

第二个查询给出：

+------------+---------+-----------+
|    day     | Country | Count_BUY |
+------------+---------+-----------+
| 17-11-2020 | IT      |        50 |
| 17-11-2020 | US      |        70 |
| 18-11-2020 | IT      |       200 |
| 18-11-2020 | US      |        50 |
+------------+---------+-----------+

现在我想将这两个结果合二为一：

+------------+---------+-------+------+-----------+
|    day     | Country | Count | Mail | Count_BUY |
+------------+---------+-------+------+-----------+
| 17-11-2020 | IT      |   200 |  100 |        50 |
| 17-11-2020 | US      |   250 |  100 |        70 |
| 18-11-2020 | IT      |   350 |  300 |       200 |
| 18-11-2020 | US      |   200 |  100 |        50 |
+------------+---------+-------+------+-----------+

如何执行此查询？ 我正在使用 mysql 谢谢

Answer 1

简单的方法：您可以加入查询。

select *
from ( <your first query here> ) first_query
join ( <your second query here> ) second_query using (day_month_year, country)
order by day_month_year, country;

这是一个内连接。 当然，您也可以外部连接。 但是，MySQL 不支持完全外部联接。 如果需要，则必须查找如何在 MySQL 中模拟完整的外部联接。

困难的方式;-) 合并查询。

如果我没记错的话，你的两个查询可以简化为

select
  date(created_on),
  branch_id as country,
  count(*) as count_products,
  count(distinct p.email) as count_emails
from db.prod_id
where created_on >= date '2020-11-17'
and branch_id  in (select country from db.country where type in (1, 2))
group by date(created_on), branch_id
order by date(created_on), branch_id;

和

select
  date(created_on),
  branch_id as country,
  count(*) as count_buy
from db.prod_id
where created_on >= date '2020-11-17'
and status_id <> 25
and prod_id in (select prod_id from prod_properties where property_id = 5 and status_id <> 25)
group by date(created_on), branch_id
order by date(created_on), branch_id;

两者结合应该是

select
  date(created_on),
  branch_id as country,
  sum(branch_id in (select country from db.country where type in (1, 2)) as count_products,
  count(distinct case when branch_id  in (select country from db.country where type in (1, 2) then p.email end) as count_emails,
  sum(status_id <> 25 and prod_id in (select prod_id from prod_properties where property_id = 5 and status_id <> 25)) as count_buy
from db.prod_id
where created_on >= date '2020-11-17'
group by date(created_on), branch_id
order by date(created_on), branch_id;

您会看到，查询共有的条件保留在 where 子句中，而其他条件则位于聚合函数内部。

sum(boolean)是sum(case when boolean then 1 else 0 end)缩写，即它计算 MySQL 中满足条件的行数。