Hi,
You are trying to insert value for identity column.refer below code
SQL
DECLARE @UserActivation AS TABLE(ID INT IDENTITY(1,1),Code NVARCHAR(100))
-- This will give you error.
--INSERT INTO @UserActivation VALUES(123,'sr@4455fd')
-- This will executed successfully.
INSERT INTO @UserActivation(Code) VALUES('123dsfgee@se')
Or
SET IDENTITY_INSERT tablename ON
INSERT INTO tablename VALUES(123,'sr@4455fd')
SET IDENTITY_INSERT tablename OFF
I hope this will help you out.