如何有條件地過濾 SQL 中的查詢？

Question

我有一個查詢顯示每個 shop_id 和國家/地區的收入，如下所示。

select shop_id,
       country,
       start_date,
       sum(earnings) as earnings
       
from x
where country IN ('DE', 'IT', 'ES')     
group by 1,2,3

但是，我想在國家DE只有三個商店，而在國家rest的所有商店。

shop_id IN ('1', '2', '3')

我怎樣才能做到這一點？

Answer 1

聽起來您的條件可以使用一些嵌套，如下所示：

select shop_id,
       country,
       start_date,
       sum(earnings) as earnings
       
from x
where country IN ('IT', 'ES') 
OR (country = 'DE' AND sop_id IN ('1','2','3'))
group by 1,2,3

Answer 2

您可以在WHERE子句中添加一個CASE語句，該語句檢查country列中的 DE 並僅返回指定的三個shop_id ，否則返回shop_id 。

WHERE
CASE 
    WHEN country = 'DE' AND shop_id IN ('1', '2', '3') THEN 1
    WHEN country IN ('IT', 'ES') THEN 1
    ELSE 0
END = 1