Question

我有一个包含以下列的表：Reportdate，Category。



Reportdate     Category
-------------------
01/01/2013     IT
01/01/2013     Grounds
01/01/2013     HVAC
01/03/2013     HVAC
02/01/2013     IT
02/02/2013     IT
02/02/2013     HVAC
02/02/2013     Grounds

我需要一个输出以下内容的查询：



           Jan     Feb
---------------------------    
IT         1       2
Grounds    1       1
HVAC       2       1

如果有人可以提供帮助，我会非常感激。感谢

Answer 1

一种简单的方法是使用条件聚合：

select category,
       sum(case when extract(month from reportdate) = 1 then 1 else 0 end) as Jan,
       sum(case when extract(month from reportdate) = 2 then 1 else 0 end) as Feb
from table
group by category;

Answer 2

您可以使用PIVOT，也可以尝试以下方法：

SELECT category
     , SUM(DECODE(EXTRACT(MONTH FROM reportdate), 1, 1, 0)) AS "Jan"
     , SUM(DECODE(EXTRACT(MONTH FROM reportdate), 2, 1, 0)) AS "Feb"
     , SUM(DECODE(EXTRACT(MONTH FROM reportdate), 3, 1, 0)) AS "Mar"
     , SUM(DECODE(EXTRACT(MONTH FROM reportdate), 4, 1, 0)) AS "Apr"
     , SUM(DECODE(EXTRACT(MONTH FROM reportdate), 5, 1, 0)) AS "May"
     , SUM(DECODE(EXTRACT(MONTH FROM reportdate), 6, 1, 0)) AS "Jun"
     , SUM(DECODE(EXTRACT(MONTH FROM reportdate), 7, 1, 0)) AS "Jul"
     , SUM(DECODE(EXTRACT(MONTH FROM reportdate), 8, 1, 0)) AS "Aug"
     , SUM(DECODE(EXTRACT(MONTH FROM reportdate), 9, 1, 0)) AS "Sep"
     , SUM(DECODE(EXTRACT(MONTH FROM reportdate), 10, 1, 0)) AS "Oct"
     , SUM(DECODE(EXTRACT(MONTH FROM reportdate), 11, 1, 0)) AS "Nov"
     , SUM(DECODE(EXTRACT(MONTH FROM reportdate), 12, 1, 0)) AS "Dec"
  FROM mytable
 GROUP BY category

如果你想按年份区分可能会使事情变得复杂的事情！

按月和类别拆分日期范围

2 个答案: