Mysql 一个“选择”查询生成12个结果集

我有一个名为VAT的表，我需要生成月度VAT报告。下面是我所做的

    SELECT SUM(Amount) AS "January" 
    WHERE current_time_stamp BETWEEN '2014-01-01' AND '2014-01-310'
    FROM VAT

---

就像上面的查询一样，我有12个关于1月、2月、3月等的查询。因此，我不写12个，有没有办法在一个查询中获得所有这些信息？

使用

分组方式，如下所示：

SELECT SUM(Amount), MONTH(current_time_stamp) AS `Month` 
FROM VAT
WHERE current_time_stamp BETWEEN '2014-01-01' AND '2014-12-31'
GROUP BY MONTH(current_time_stamp)

但是，如果你有很多记录，它可能会很慢。
类似的情况会扩展到12个月

SELECT MAX(X.January) AS January, MAX(X.February) AS February FROM
(
SELECT SUM(Amount) AS January, 0 AS February
    WHERE current_time_stamp BETWEEN '2014-01-01' AND '2014-01-31'
    FROM VAT
UNION
SELECT 0 AS January, SUM(Amount) AS February
    WHERE current_time_stamp BETWEEN '2014-02-01' AND '2014-02-29'
    FROM VAT
) X

或者你也可以这样做：

SELECT 'January' AS Month, SUM(Amount) AS Amount
    WHERE current_time_stamp BETWEEN '2014-01-01' AND '2014-01-31'
    FROM VAT
UNION
 SELECT 'February' AS Month, SUM(Amount) AS Amount
    WHERE current_time_stamp BETWEEN '2014-02-01' AND '2014-02-29'
    FROM VAT

您可以在case语句中使用条件求和，下面的查询将为您提供一行12列的每月求和

SELECT 
   SUM(case when current_time_stamp BETWEEN '2014-01-01' AND '2014-01-31' then Amount else 0 end) AS `January` ,
   SUM(case when current_time_stamp BETWEEN '2014-02-01' AND '2014-02-29' then Amount else 0 end) AS `Febuary` ,
   .
   .
   .
   SUM(case when current_time_stamp BETWEEN '2014-12-01' AND '2014-12-31' then Amount else 0 end) AS `December` 
 FROM VAT

select t.mnth_amt,t.mnth 
from (
     select sum(amount) as mnth_amt,MONTH(current_time_stamp ) as mnth from vat where current_time_stamp BETWEEN '2014-01-01' AND  
     '2014-12-31' GROUP BY MONTH(current_time_stamp) 
     ) t order by mnth