我想在交易日期之间输出股票，如果没有交易日期，它仍应显示MySQL库存系统上的所有股票

Question

我当前的查询：

select stock.id, stock.name, sum(amount) from stock
left join stock_detail on stock.id = stock_detail.stock_id
where transact_at BETWEEN ('2018-06-15') and ('2018-06-16')
group by stock.id

但它不会显示在库存明细表上没有条目的其他库存。

表1：股票

id   name
1    chicken
2    beef
3    pork
4    drink

表2：StockDetail

id  stock_id    type    amount  transact_date   
1   1           in      1000    15/06/2018  
2   1           in      500     15/06/2018  
3   2           in      300     16/06/2018  

我想要输出

id      name       total_amount 
1       chicken    1500
2       beef       300
3       pork       0
4       drink      0

Answer 1

您必须将日期谓词从WHERE移至ON：

select stock.id, stock.name, coalesce(sum(amount) , 0)
from stock
left join stock_detail 
   on stock.id = stock_detail.stock_id 
      and transact_date BETWEEN ('2018-06-15') and ('2018-06-16')
group by stock.id

Demo here