的MySQL从三个查询

Question

结合数据是否有办法让我得到一个不同的名称，那么在今天，明天的数量，这些查询组合，和后天

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
鉴于表
名称，数量，DELIVERY_DATE
芝加哥，1，2011-11-22
纽约，2，2011-11-22
芝加哥，3，2011-11-23

我希望
芝加哥，1，3，0
纽约，1，0，0

Answer 1

如果你是试图将它们全部结合在一个数据集中，您可以试试这个，

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 

这将在TSQL（MS SQL）的工作，希望它在MySQL的

Answer 2

UNION/UNION ALL将这样的伎俩：

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 

相同的语法，这是MySQL的更多风格