How can I reseed an identity column in a T-SQL table variable?

Question

I have a T-SQL table variable (not a table) which has an auto incrementing identity column. I want to clear all data from this variable and reset the identity column value to 1. How can this be done?

Answer 1

Truncating the table will dump ALL the data, and reset the identity seed.

Otherwise, you can use this call to reset the identity while retaining any of the data:

DBCC CHECKIDENT (yourtableName, reseed, @NewStartSeedValue) 

Answer 2

If you're using a table variable, you can't do it. If it were a table, you could truncate it or use DBCC CHECKIDENT. But, if you have to use a table variable, you have to use something other than an identity column. Or, more accurately, use the identity column in your table variable but output using ROWNUMBER:

DECLARE @t table (pkint int IDENTITY(1,1), somevalue nvarchar(50)) INSERT INTO @t (somevalue) VALUES( 'one') INSERT INTO @t (somevalue) VALUES('twp') INSERT INTO @t (somevalue) VALUES('three') SELECT row_number() OVER (ORDER BY pkint), somevalue FROM @t DELETE FROM @t INSERT INTO @t (somevalue) VALUES('four') SELECT row_number() OVER (ORDER BY pkint), somevalue FROM @t 

It's the best you can do with the table variable.