T-SQL汇总

Question

I'm trying to create result set with 3 columns. Each column coming from the summation of 1 Column of Table A but grouped by different ID's. Here's an overview of what I wanted to do..

Table A
ID       Val.1      
1          4
1          5
1          6
2          7
2          8
2          9
3         10
3         11   
3         12

I wanted to create something like..

ROW       SUM.VAL.1          SUM.VAL.2         SUM.VAL.3
1            15                 21                33

I understand that I can not get this using UNION, I was thinking of using CTE but not quite sure with the logic.

Answer 1

You need conditional Aggregation

select 1 as Row,
       sum(case when ID = 1 then Val.1 end),
       sum(case when ID = 2 then Val.1 end),
       sum(case when ID = 3 then Val.1 end)
From yourtable 

You may need dynamic cross tab or pivot if number of ID's are not static

DECLARE @col_list VARCHAR(8000)= Stuff((SELECT ',sum(case when ID = '+ Cast(ID AS VARCHAR(20))+ ' then [Val.1] end) as [val.'+Cast(ID AS VARCHAR(20))+']'
                    FROM   Yourtable
                    GROUP  BY ID
                    FOR xml path('')), 1, 1, ''),
        @sql      VARCHAR(8000) 

exec('select 1 as Row,'+@col_list +'from Yourtable')

• Live Demo

Answer 2

I think pivoting the data table will yield the desired result.

IF OBJECT_ID('tempdb..#TableA') IS NOT NULL
    DROP TABLE #TableA

CREATE TABLE #TableA
(
    RowNumber INT, 
    ID INT,
    Value INT
)
INSERT #TableA VALUES (1, 1, 4)
INSERT #TableA VALUES (1, 1, 5)
INSERT #TableA VALUES (1, 1, 6)
INSERT #TableA VALUES (1, 2, 7)
INSERT #TableA VALUES (1, 2, 8)
INSERT #TableA VALUES (1, 2, 9)
INSERT #TableA VALUES (1, 3, 10)
INSERT #TableA VALUES (1, 3, 11)
INSERT #TableA VALUES (1, 3, 12)

-- https://msdn.microsoft.com/en-us/library/ms177410.aspx

SELECT RowNumber, [1] AS Sum1, [2] AS Sum2, [3] AS Sum3
FROM 
(
    SELECT RowNumber, ID, Value 
    FROM #TableA
) a
PIVOT
(
    SUM(Value)
    FOR ID IN ([1], [2], [3])
) AS p

This technique works if the ids you are seeking are constant, otherwise I imagine some dyanmic-sql would work as well if changing ids are needed.

https://msdn.microsoft.com/en-us/library/ms177410.aspx