Question

Could anybody guide me how to pivot my data. I have:

RowID Dimension Value
1 Country Italy
1 Year 2011
1 GDP 4
1 Population 6
2 Country Spain
2 Year 2011
2 GDP 7
2 Population 5

I want in a such way:

RowID Country Year GDP Population
1 Italy 2011 4 6
2 Spain 2011 7 5

P.S. I use MS SQL Server 2008 R2 Express Edition. I tried to use PIVOT but it returned many rows with NULL so I could not figure out.

Answer 1

You can use PIVOT for this. This can be hard-coded if you know all of the values:

select *
from
(
  select rowid, dimension, value
  from yourtable
) src
pivot
(
  max(value)
  for dimension in ([Country], [Year], [GDP], [Population])
) piv

See SQL Fiddle with Demo

Or of you do not have access to the PIVOT function, then you can use an aggregate with a CASE:

select rowid,
  max(case when dimension = 'country' then value end) country,
  max(case when dimension = 'Year' then value end) Year,
  max(case when dimension = 'GDP' then value end) GDP,
  max(case when dimension = 'Population' then value end) Population
from yourtable
group by rowid

See SQL Fiddle with Demo

If you have an unknown number of values, then you can use dynamic sql:

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

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

set @query = 'SELECT rowid, ' + @cols + ' from 
             (
                select rowid, dimension, value
                from yourtable
            ) x
            pivot 
            (
                max(value)
                for dimension in (' + @cols + ')
            ) p '

execute(@query)

See SQL Fiddle with Demo