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Asked: 2026-05-24T06:30:52+00:00

I’m working with a legacy SQL Server database which has a core table with

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I’m working with a legacy SQL Server database which has a core table with a bad primary key.

The key is of type NVARCHAR(50) and contains an application-generated string based on various things in the table. For obvious reasons, I’d like to replace this key with an auto-incrementing (identity) INT column.

This is a huge database and we’re upgrading it piece-by-piece. We want to minimize the changes to tables that other components write to. I figured I could change the table without breaking anything by just:

  1. Adding the new Id column to the table and making it nullable
  2. Filling it with unique integers and making it NOT NULL
  3. Dropping the existing primary key while ensuring there’s a uniqueness constraint still on that column
  4. Setting the new Id column to be the new primary key and identity

Item 3 is proving very painful. Because this is a core table, there are a lot of other tables with foreign key constraints on it. To drop the existing primary key, it seems I have to delete all these foreign key constraints and create them again afterwards.

Is there an easier way to do this or will I just have to script everything?

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  1. Editorial Team

    Afraid that is the bad news. We just got through a big project of doing the same type of thing, although our head DBA had a few tricks up his sleeve. You might look at something like this to get your scripts generated for the flipping of the switch:

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