Hi, You probably don't want to go there as far as creating a custom key. Anyway you haven't convinced me that this is really necessary so I would try to use the standard functionality so you don't get off on the wrong foot. 😉

DROP TABLE Test

CREATE TABLE [dbo].[Test](

[MyDate] [datetime] NULL

) ON [PRIMARY]

INSERT INTO Test

SELECT '1/1/2011 3:00:00 PM' UNION

SELECT '1/1/2011 4:00:00 PM' UNION

SELECT '1/1/2011 5:00:00 PM' UNION

SELECT '1/2/2011 5:00:00 PM' UNION

SELECT '1/2/2011 5:10:00 PM'

SELECT * FROM Test

You should be able to use a CTE to generate a sequential number

SELECT

'AL ' + REPLACE(CONVERT(VARCHAR(10), MyDate, 101), '/', '') + '-' +

--here you would add the code that would resequence for each new date

--since I am not too good with this I am hoping someone smarter than me will fill in the blanks here

FROM Test

This assumes you don't need to store this pseudo-key, just present it.