如何在sql中垂直获取列总数

Question

我有水平的总数，我想要实现蓝色的最后一行，我使用了这个查询

SELECT 
    DepartmentName,
    SUM(CASE WHEN Risk = 'High' THEN 1 ELSE 0 END) High,
    SUM(CASE WHEN Risk = 'Medium' THEN 1 ELSE 0 END) Medium,
    SUM(CASE WHEN Risk = 'Low' THEN 1 ELSE 0 END) Low,
    SUM(CASE WHEN Risk = 'High' THEN 1 ELSE 0 END) 
        + SUM(CASE WHEN Risk = 'Medium' THEN 1 ELSE 0 END) 
        + SUM(CASE WHEN Risk = 'Low' THEN 1 ELSE 0 END) Total
FROM    
    TableName
GROUP BY 
    DepartmentName

我怎样才能获得最后一行？

Answer 1

可以使用Grouping sets

完成此操作

SELECT COALESCE(DepartmentName, 'Total'),
   SUM(CASE WHEN Risk = 'High' THEN 1 ELSE 0 END) High,
   SUM(CASE WHEN Risk = 'Medium' THEN 1 ELSE 0 END) Medium,
   SUM(CASE WHEN Risk = 'Low' THEN 1 ELSE 0 END) Low,
   SUM(CASE WHEN Risk = 'High' THEN 1 ELSE 0 END) 
                        + SUM(CASE WHEN Risk = 'Medium' THEN 1 ELSE 0 END) 
                        + SUM(CASE WHEN Risk = 'Low' THEN 1 ELSE 0 END) Total
   FROM    TableName
   GROUP BY GROUPING SETS ((DepartmentName), ())

Answer 2

使用ROLLUP

也可以实现同样的效果

SELECT 
      COALESCE(DepartmentName, 'Total') DepartmentName,
      SUM(CASE WHEN Risk = 'High' THEN 1 ELSE 0 END) High,
      SUM(CASE WHEN Risk = 'Medium' THEN 1 ELSE 0 END) Medium,
      SUM(CASE WHEN Risk = 'Low' THEN 1 ELSE 0 END) Low,
      SUM(CASE WHEN Risk IN ('High', 'Medium', 'Low') THEN 1 ELSE 0 END) Total   
FROM table
GROUP BY DepartmentName with ROLLUP

Answer 3

我能想到的最简单的

select Department, High, Medium, Low, Total from MY_TABLE
union all
select 'Total', sum(High), sum(Medium), sum(Low), sum(Total)  from MY_TABLE