How to Alter a table for Identity Specification is identity SQL Server

Question

---

not working

ALTER TABLE ProductInProduct ALTER COLUMN Id KEY IDENTITY (1, 1);

Check Image

I have a table ProductInProduct is want its id should be Unique..

Answer 1

You don't set value to default in a table. You should clear the option "Default value or Binding" first.

Answer 2

You cannot "convert" an existing column into an IDENTITY column - you will have to create a new column as INT IDENTITY:

ALTER TABLE ProductInProduct 
ADD NewId INT IDENTITY (1, 1);

Update:

OK, so there is a way of converting an existing column to IDENTITY. If you absolutely need this - check out this response by Martin Smith with all the gory details.