TSQL Pivot Long List of Columns

Question

I am looking to use pivot function to convert row values of a column into separate columns. There are 100+ distinct values in that column and hard-coding each and every single value in the 'for' clause of the pivot function would be very time consuming and not good from maintainability purposes. I was wondering if there is any easier way to tackle this problem?

Thanks

Answer 1

You can use Dynamic SQL in a PIVOT for this type of query. Dynamic SQL will get the list of the items that you want to transform on execution which prevents the need to hard-code each item:

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)

See SQL Fiddle with Demo

If you post a sample of data that you need to transform, then I can adjust my query to demonstrate.