Question

QUERY 1（第一张表 - 存入）

select sum(s.liquid_quantity) as 'stock in total' from stockin_detail s 
left join reagent r on r.id = s.reagent_id group by r.name

QUERY 2（第二张表 - 库存结束）

select sum(t.consumption)as 'stock out total' ,r.name from stock_out s 
inner join test_consumption t on s.consumption_id = t.id 
inner join reagent r on r.id = t.reagent_id group by r.name

QUERY 1

stock in  |r.name     
100       |Reagent2                 
100       |Reagent3

QUERY 2

stock out  |r.name     
40         |Reagent2                 
20         |Reagent3

我尝试这样做，但它不会减去因为每个嵌套的select语句返回多个列＆＃39;由group by引起的错误消息。我也尝试删除该组，但最终梳理了两个不同的股票，然后减去。

SELECT QUERY1 – QUERY2 as ‘current stocks’

预期出现

current stock|r.name  
60           |Reagent2                 
80           |Reagent3

Answer 1

为什么不将两个查询转储到内联视图中，然后将它们连接在一起？

这样的事情会让你前进。内联视图别名'i'是库存和内联视图别名'o'是库存：

select i.name,i.in-ifnull(o.out,0) as 'current stock'
from
 (
  select sum(s.liquid_quantity) as in,r.name 
  from stockin_detail s 
  left join reagent r on r.id = s.reagent_id 
  group by r.name
 ) i
 left outer join
 (
  select sum(t.consumption)as 'out' ,r.name from stock_out s 
  inner join test_consumption t on s.consumption_id = t.id 
  inner join reagent r on r.id = t.reagent_id 
  group by r.name
 ) o on i.name = o.name;

获取数量Mysql

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