如何合併兩個MySQL查詢

Question

我想這兩個查詢有兩個隊長相結合應該是平等的：

select distinct(captain_name),sum(finaldiscount) as tot,payment_mode 
from order_master 
where payment_mode='card' 
group by captain_name 

select distinct(captain_name),sum(finaldiscount) as tot,payment_mode 
from order_master 
where payment_mode='cash' 
group by captain_name 

Answer 1

結合可以是JOIN或UNION

對於JOIN ：

Select * 
from 
(select distinct(captain_name) capName,sum(finaldiscount) as tot,payment_mode from order_master where payment_mode='card' group by captain_name) t1 
INNER JOIN 
(select distinct(captain_name) capName,sum(finaldiscount) as tot,payment_mode from order_master where payment_mode='cash' group by captain_name) t2 on t1.capName = t2.capName 

對於聯合國ION：

Select * 
    from 
    (select distinct(captain_name) capName,sum(finaldiscount) as tot,payment_mode from order_master where payment_mode='card' group by captain_name) t1 
    UNION 
    (select distinct(captain_name) capName,sum(finaldiscount) as tot,payment_mode from order_master where payment_mode='cash' group by captain_name) t2 

Answer 2

試試這個：

SELECT captain_name, 
     SUM(CASE WHEN payment_mode = 'cash' THEN finaldiscount ELSE 0 END) AS cashTotal, 
     SUM(CASE WHEN payment_mode = 'card' THEN finaldiscount ELSE 0 END) AS cardTotal 
FROM order_master 
WHERE payment_mode IN ('cash', 'card') 
GROUP BY captain_name 

OR

SELECT captain_name, payment_mode, SUM(finaldiscount) total 
FROM order_master 
WHERE payment_mode IN ('cash', 'card') 
GROUP BY captain_name, payment_mode 

Answer 3

試試這個：

SELECT captain_name, 
     Sum(finaldiscount) AS tot, 
     payment_mode 
FROM order_master 
WHERE payment_mode IN('cash', 'card') 
     AND captain_name IN (SELECT captain_name 
          FROM order_master 
          WHERE payment_mode IN('cash', 'card') 
          GROUP BY captain_name 
          HAVING Count(DISTINCT payment_mode) = 2) 
GROUP BY captain_name,payment_mode 

子查詢將返回唯一的日其中有payment_mode，即card和cash。然後選擇captain_name和group by那些行，按captain_name,payment_mode。

，如果你不想單獨的行爲card和cash然後使用此：

SELECT captain_name,SUM(finaldiscount) 
FROM order_master 
WHERE payment_mode IN('cash', 'card') 
GROUP BY captain_name 
HAVING Count(DISTINCT payment_mode) = 2 

注：我認爲two captain should be equal意味着只有那些被兩個查詢返回的隊長，應當由合併返回查詢。