Finding changes

Hoping one of you experts can help me - im writing an application and need to run a query that returns only the difference between 2 rows...

Example:

----------------
SELECT *
FROM summary, inventory
WHERE summary.fkInventory = inventory.ID
AND inventory.ComputerName = '[SOME_NAME_HERE]'
----------------

Now - this will return 2 rows with all columns from my tables. I need to know which columns that are different - and return only those to my application.

I am a bit new to SQL ( getting there fast ) but i have no clue how to do this - or if it can be done. Otherwise i will have to compare the data in my application but i'd much prefer to let the database do the work if possible...see
http://www.nigelrivett.net/Triggers_2_Creating_Audit_Trails.html

It has code for logging changes to a column that has changed in a trigger.

You will have to loop through each column checking the values.|||Do you have exactly two rows (summeries) per inventory (computer)?

Do you realize that your query if created as you required returns everytime different columns? You can beter consider to let the query return your columnname, the original value and the changed value.

First you have to specify your different values:

SELECT 'YourFirstColumnName' AS ColName,
cast(O.YourFirstColumnName AS VARCHAR(255)) AS OriginalValue,
cast(N.YourFirstColumnName AS VARCHAR(255)) AS NewValue,
fkInventory
FROM (SELECT min(S.ID) MinID, max(S.ID) MaxID, S.fkInventory
FROM Summary S
GROUP BY S.fkInventory ) OldNew
INNER JOIN Summary O ON OldNew.MinID = O.ID INNER JOIN Summary N ON OldNew.MaxID = N.ID
WHERE O.YourFirstColumnName <> N.YourFirstColumnName

UNION

SELECT 'YourSecondColumnName' AS ColName,
cast(O.YourSecondColumnName AS VARCHAR(255)) AS OriginalValue, cast(N.YourSecondColumnName AS VARCHAR(255)) AS NewValue,
fkInventory
FROM (SELECT min(S.ID) MinID, max(S.ID) MaxID, S.fkInventory
FROM Summary S
GROUP BY S.fkInventory ) OldNew
INNER JOIN Summary O ON OldNew.MinID = O.ID INNER JOIN Summary N ON OldNew.MaxID = N.ID
WHERE O.YourSecondColumnName <> N.YourSecondColumnName

UNION

....

You got the idea to repeat the query for every column you want to compare? It's not very elegant, but under the assumptions above, you get what you want.

Then, you may use this query Q in your query like:

SELECT ColName, OriginalValue, NewValue
FROM Q
WHERE Q.fkInventory = (SELECT ID
FROM inventory WHERE ComputerName = '[SOME_NAME_HERE]')