SQL Server : Columns to Rows

sql, sql-server, t-sql, unpivot

Solution

You can use the UNPIVOT function to convert the columns into rows:

select id, entityId,
  indicatorname,
  indicatorvalue
from yourtable
unpivot
(
  indicatorvalue
  for indicatorname in (Indicator1, Indicator2, Indicator3)
) unpiv;

Note, the datatypes of the columns you are unpivoting must be the same so you might have to convert the datatypes prior to applying the unpivot.

You could also use `CROSS APPLY` with UNION ALL to convert the columns:

select id, entityid,
  indicatorname,
  indicatorvalue
from yourtable
cross apply
(
  select 'Indicator1', Indicator1 union all
  select 'Indicator2', Indicator2 union all
  select 'Indicator3', Indicator3 union all
  select 'Indicator4', Indicator4 
) c (indicatorname, indicatorvalue);

Depending on your version of SQL Server you could even use CROSS APPLY with the VALUES clause:

select id, entityid,
  indicatorname,
  indicatorvalue
from yourtable
cross apply
(
  values
  ('Indicator1', Indicator1),
  ('Indicator2', Indicator2),
  ('Indicator3', Indicator3),
  ('Indicator4', Indicator4)
) c (indicatorname, indicatorvalue);

Finally, if you have 150 columns to unpivot and you don't want to hard-code the entire query, then you could generate the sql statement using dynamic SQL:

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

select @colsUnpivot 
  = stuff((select ','+quotename(C.column_name)
           from information_schema.columns as C
           where C.table_name = 'yourtable' and
                 C.column_name like 'Indicator%'
           for xml path('')), 1, 1, '')

set @query 
  = 'select id, entityId,
        indicatorname,
        indicatorvalue
     from yourtable
     unpivot
     (
        indicatorvalue
        for indicatorname in ('+ @colsunpivot +')
     ) u'

exec sp_executesql @query;

Problem

Looking for elegant (or any) solution to convert columns to rows. Here is an example: I have a table with the following schema: ``` [ID] [EntityID] [Indicator1] [Indicator2] [Indicator3] ... [Indicator150] ``` Here is what I want to get as the result: ``` [ID] [EntityId] [IndicatorName] [IndicatorValue] ``` And the result values will be: ``` 1 1 'Indicator1' 'Value of Indicator 1 for entity 1' 2 1 'Indicator2' 'Value of Indicator 2 for entity 1' 3 1 'Indicator3' 'Value of Indicator 3 for entity 1' 4 2 'Indicator1' 'Value of Indicator 1 for entity 2' ``` And so on.. Does this make sense? Do you have any suggestions on where to look and how to get it done in T-SQL?

Original source

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