如何在 Sequelize、Mysql、Node 中合并多个查询

Question

我想根据类型获取 4 种类型的计数，因为我有 4 个单独的查询，但我只想使用一个查询来一次获取所有 4 个计数。

查询 1：

SELECT count(*) as totalCount FROM orders INNER JOIN order_view ON orders.id= order_view.id 
WHERE order_view.order_type = 'Type1'

查询 2：

SELECT count(*) as totalCount FROM orders INNER JOIN order_view ON orders.id= order_view.id 
WHERE order_view.order_type = 'Type2'

查询 3：

SELECT count(*) as totalCount FROM orders INNER JOIN order_view ON orders.id= order_view.id 
WHERE order_view.order_type = 'Type3'

查询 4：

SELECT count(*) as totalCount FROM orders INNER JOIN order_view ON orders.id= order_view.id 
WHERE order_view.order_type = 'Type4'

我正在通过 Sequelize 查找查询，但似乎找不到任何文档。

Answer 1

使用条件聚合：

select 
    sum(ov.order_type = 'type1') as totalcount1,
    sum(ov.order_type = 'type2') as totalcount2
    sum(ov.order_type = 'type3') as totalcount3
    sum(ov.order_type = 'type4') as totalcount4
from orders o
inner join order_view on o.id = ov.id 
where ov.order_type in ('type1', 'type2', 'type3', 'type4')

目前还不清楚为什么在查询中需要表orders。这可能只是你想要的：

select 
    sum(ov.order_type = 'type1') as totalcount1,
    sum(ov.order_type = 'type2') as totalcount2
    sum(ov.order_type = 'type3') as totalcount3
    sum(ov.order_type = 'type4') as totalcount4
from order_view
where ov.order_type in ('type1', 'type2', 'type3', 'type4')