的MySQL從三個查詢

Question

結合數據是否有辦法讓我得到一個不同的名稱，那麼在今天，明天的數量，這些查詢組合，和後天

select name, SUM(qty) as qty_today, 0 as qty_tomororow, 0 as qty_om 
from order_item 
where delivery_date = '2011-11-22' 
group by name 
union all 
select name, qty as qty_today, SUM(qty) as qty_tomororow, 0 as qty_om 
from order_item 
where delivery_date = '2011-11-23' 
group by name 
union all 
select name, 0 as qty_today, 0 as qty_tomororow, SUM(qty) as qty_om 
from order_item 
where delivery_date = '2011-11-24' 
group by name 

UPDATE
鑑於表
名稱，數量，DELIVERY_DATE
芝加哥，1，2011-11-22
紐約，2，2011-11-22
芝加哥，3，2011-11-23

我希望
芝加哥，1，3，0
紐約，1，0，0

Answer 1

如果你是試圖將它們全部結合在一個數據集中，您可以試試這個，

SELECT name, 
     SUM(CASE WHEN delivery_date = '2011-11-22' THEN qty 
       ELSE 0 END) AS qty_today, 
     SUM(CASE WHEN delivery_date = '2011-11-23' THEN qty 
       ELSE 0 END) AS qty_tomororow, 
     SUM(CASE WHEN delivery_date = '2011-11-24' THEN qty 
       ELSE 0 END) AS qty_om 
from order_item 
where delivery_date between '2011-11-22' and '2011-11-24' 
group by name 

這將在TSQL（MS SQL）的工作，希望它在MySQL的

Answer 2

UNION/UNION ALL將這樣的伎倆：

select name, SUM(qty) as qty_today, 0 as qty_tomororow, 0 as qty_om 
from order_item 
where delivery_date = '2011-11-22' 
group by name 
UNION ALL 
select name, qty as qty_today, SUM(qty) as qty_tomororow, 0 as qty_om 
from order_item 
where delivery_date = '2011-11-23' 
group by name 
UNION ALL 
select name, 0 as qty_today, 0 as qty_tomororow, SUM(qty) as qty_om 
from order_item 
where delivery_date = '2011-11-24' 
group by name 

Answer 3

select name, SUM(qty) as qty_today, 0 as qty_tomororow, 0 as qty_om 
from order_item 
where delivery_date IN ('2011-11-22', '2011-11-23', '2011-11-24') 
group by delivery_date, name 

Answer 4

SELECT name, 
     SUM(if (delivery_date = '2011-11-22' , qty , 0)) AS qty_today, 
     SUM(if (delivery_date = '2011-11-23' , qty , 0)) AS qty_tomororow, 
     SUM(if (delivery_date = '2011-11-24' , qty , 0)) AS qty_om 
from order_item group by name 

相同的語法，這是MySQL的更多風格