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How to create a pivot table in Transact / SQL?

Source table

MemID Condition_ID Condtion_Result
----------------------------------
1     C1           0
1     C2           0
1     C3           0
1     C4           1
2     C1           0
2     C2           0
2     C3           0
2     C4           0

The expected view I want to create is ....

MemID C1 C2 C3 C4
------------------
1     1  0  0  1
2     0  0  0  1

Here is another condition. In the above example, the source table has only 4 rows for this MemID. This number will change in a real situation. My pivot table (or any other solution) should select any number of condition results and display them as columns. How to do it?

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1 answer

You need to use PIVOT. You can use STATIC PIVOT, where you know the values ​​of the converted columns, or DYNAMIC PIVOT, where the columns are unknown until runtime.

Static core (see SQL Fiddle with Demo ):

select *
from 
(
    select memid, Condition_id, Condition_Result
    from t
) x
pivot
(
    sum(condition_result)
    for condition_id in ([C1], [C2], [C3], [C4])
) p

(. SQL Fiddle with Demo):

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

SET @cols = STUFF((SELECT distinct ',' + QUOTENAME(c.condition_id) 
            FROM t c
            FOR XML PATH(''), TYPE
            ).value('.', 'NVARCHAR(MAX)') 
        ,1,1,'')


set @query = 'SELECT memid, ' + @cols + ' from 
            (
                select MemId, Condition_id, condition_result
                from t
           ) x
            pivot 
            (
                sum(condition_result)
                for condition_id in (' + @cols + ')
            ) p '


execute(@query)

.

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