基于多列透视数据

Question

I wonder if it is possible to pivot the following table:

10  A  ddd
24  B  fff
34  B  ddd
12  A  ddd

I need to pivot it like this

A  B  text
-- -- ----
22 34 ddd
0  24 fff

Answer 1

You can use the PIVOT function for this:

select IsNull(A, 0) A, 
  IsNull(B, 0) B, 
  txt
from
(
  select num, let, txt
  from yourtable
) src
pivot
(
  sum(num)
  for let in (A, B)
) piv

See SQL Fiddle with Demo

If your values are known, then you can hard-code them similar to the query above. But if you have an unknown number of values, then you can use dynamic sql to create the query string. Your dynamic sql code would look like this:

DECLARE @cols AS NVARCHAR(MAX),
    @colsNull AS NVARCHAR(MAX),
    @query  AS NVARCHAR(MAX)

select @cols = STUFF((SELECT distinct ',' + QUOTENAME(Let) 
                    from yourtable
            FOR XML PATH(''), TYPE
            ).value('.', 'NVARCHAR(MAX)') 
        ,1,1,'')

select @colsNull = STUFF((SELECT distinct ',IsNull(' + QUOTENAME(Let)+', 0) as '+QUOTENAME(Let) 
                    from yourtable
            FOR XML PATH(''), TYPE
            ).value('.', 'NVARCHAR(MAX)') 
        ,1,1,'')

set @query = 'SELECT ' + @colsNull + ', txt from 
             (
                select num, let, txt
                from yourtable
            ) x
            pivot 
            (
                sum(num)
                for let in (' + @cols + ')
            ) p '

execute(@query)

See SQL Fiddle with Demo

The result of both queries is:

|  A |  B | TXT |
-----------------
| 22 | 34 | ddd |
|  0 | 24 | fff |

Answer 2

Oracle query:

SELECT NVL(DECODE(area, 'A', total), 0) A
     , NVL(DECODE(area, 'B', total), 0) B
     , val
FROM
 (
  SELECT area, SUM(id) total, val
    FROM stack_test
  GROUP BY area, val
 )
 /
A   B   VAL
--  --  --
0   24  fff
22  0   ddd
0   34  ddd