Reuse identity value after deleting rows

sql sql-server tsql sql-server-2008 identity
Jeremy picture Jeremy · Nov 26, 2010 · Viewed 35.1k times · Source

Is it possible to reuse an identity field value after deleting rows in SQL Server 2008 Express? Here is an example. Suppose I have a table with an Id field as a primary key (identity). If I add five rows, I will have these 5 Ids: 1, 2, 3, 4, 5. If I were to delete these rows, and then add five more, the new rows would have Ids: 6, 7, 8, 9, 10. Is it possible to let it start over at 1 again?

Do I have to delete data from another table in order to accomplish this? Thanks for your help.

Answer

OMG Ponies picture OMG Ponies · Nov 26, 2010

You can use the following to set the IDENTITY value:

DBCC CHECKIDENT (orders, RESEED, 999)

That means you'll have to run the statement based on every DELETE. That should start to highlight why this is a bad idea...

The database doesn't care about sequential values - that's for presentation only.

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