Question

Using SQL, how do I convert a single row table like this…

Firstname Surname Address1        City   Country
--------- ------- --------------- ------ -------
Bob       Smith   101 High Street London UK

…to a table of name-value pairs like this:

Name      Value
--------- -------
Firstname   Bob
Surname     Smith
Address1    101 High Street
City        London
Country     UK

This script will create the original table:

create table #OriginalTable (Firstname varchar(10), Surname varchar(10), 
Address1 varchar(50), City varchar(10), Country varchar(10))
insert into #OriginalTable 
select 
'Bob' Firstname, 
'Smith' Surname, 
'101 High Street' Address1, 
'London' City, 
'UK' Country

I’m after a generic solution that does not depend on the columns names always being what they are in the example.

EDIT:
I’m using SQL Server 2005.
The solution I’m after is the SQL script to convert this data into a name-value pair table

ANSWER:
Using the answer that I accepted as the answer, this is what I’ve used:

select   
result.Name, 
result.Value    
from   
  (select
    convert(sql_variant,FirstName) AS FirstName,
    convert(sql_variant,Surname) AS Surname,
    convert(sql_variant,Address1) AS Address1,
    convert(sql_variant,City) AS City,
    convert(sql_variant,Country) AS Country
    from #OriginalTable) OriginalTable
  UNPIVOT (Value For Name In (Firstname, Surname, Address1, City, Country)) as result

Answer 1

Basically you have two problems – to UNPIVOT, the data types have to be conformed. The other problem is that the number of columns is unknown. You want to reach something of the form:

WITH    conformed
      AS ( SELECT   CONVERT(VARCHAR(255), [Firstname]) AS [Firstname],
                    CONVERT(VARCHAR(255), [Surname]) AS [Surname],
                    CONVERT(VARCHAR(255), [Address1]) AS [Address1],
                    CONVERT(VARCHAR(255), [City]) AS [City],
                    CONVERT(VARCHAR(255), [Country]) AS [Country]
           FROM     so1526080
         )
SELECT  ColumnKey,
        ColumnValue
FROM    conformed UNPIVOT ( ColumnValue FOR ColumnKey IN ( [Firstname], [Surname], [Address1], [City], [Country] ) ) AS unpvt

So using a dynamic SQL PIVOT using metadata (you might need to fix this up with TABLE_SCHEMA, etc):

DECLARE @table_name AS SYSNAME
SET @table_name = 'so1526080'
DECLARE @conform_data_type AS VARCHAR(25)
SET @conform_data_type = 'VARCHAR(255)'

DECLARE @column_list AS VARCHAR(MAX)
DECLARE @conform_list AS VARCHAR(MAX)

SELECT  @conform_list = COALESCE(@conform_list + ', ', '') + 'CONVERT('
        + @conform_data_type + ', ' + QUOTENAME(COLUMN_NAME) + ') AS '
        + QUOTENAME(COLUMN_NAME),
        @column_list = COALESCE(@column_list + ', ', '')
        + QUOTENAME(COLUMN_NAME)
FROM    INFORMATION_SCHEMA.COLUMNS
WHERE   TABLE_NAME = @table_name

DECLARE @template AS VARCHAR(MAX)

SET @template = '
WITH    conformed
          AS ( SELECT  {@conform_list}
               FROM     {@table_name}
             )
    SELECT  ColumnKey,
            ColumnValue
    FROM    conformed UNPIVOT ( ColumnValue FOR ColumnKey IN ( {@column_list} ) ) AS unpvt
    '

DECLARE @sql AS VARCHAR(MAX)
SET @sql = REPLACE(REPLACE(REPLACE(@template, '{@conform_list}', @conform_list),
                           '{@column_list}', @column_list), '{@table_name}',
                   @table_name)    

PRINT @sql
EXEC ( @sql
    )