How to create a table of name-value pairs in SQL - sql

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
)

Answer 2

This is MS SQL Server solution using JSON. You don't need to specify the column names and data types. All you need to do is to specify the table name and valid where condition on line 3.
DECLARE #TEMP TABLE (JSONHOLDER NVARCHAR(MAX));
INSERT INTO #TEMP
SELECT (SELECT * FROM YOURTABLE WHERE YOURID = 2589 FOR JSON AUTO) AS JSONHOLDER
SELECT [KEY] as ColumnName, [VALUE] as ColumnValue FROM (SELECT [KEY] AS OLDKEY, [VALUE] AS OLDVALUE FROM #TEMP A
CROSS APPLY OPENJSON(A.JSONHOLDER)) B CROSS APPLY OPENJSON(B.OLDVALUE)

Answer 3

Not that it be a complete solution, but is a brainstorm idea, what if you cross join information_schema.columns with your table?
SELECT column_name, OriginalTable.*
FROM information_schema.columns
CROSS JOIN OriginalTable
WHERE table_name = 'OriginalTable'
AND /* PRIMARY KEY FILTER HERE*/

Answer 4

Often it is most effective to pivot in the application using application code. Pivoting does not tend to be a database's strong point.

Answer 5

Use two tables. One table as a table of 'keys' and the main table contains an id to the keys table, together with a value.
Then, you can add stuff like client_id or whatever to the main table as well and set a unique key on client_id and key_id.

Answer 6

This sounds like the kind of things the PIVOT clause can do in SQL Server since 2005 (look for the first example), but you don't mention which database engine you use.