Question

I am working on “cleaning up” a database and need to synchronize the IDENTITY columns. I am using stored procedures to handle the data and mirror it from one table to the next (after cleaning it and correcting the datatypes). At some point in the future I will want to cut off the old table and use only the new table, my question is how to have the IDENTITY field stay in sync while they are both in use… Once the old table is removed the new one will need to continue auto-incrementing and rebuilding/altering it to change the IDENTITY field is not an option. Is this possible or is there a better way to go about this?

My other thought was to create a lookup table to store the ID columns of both tables and anytime there is an insert in the new table take the old ID and new ID and insert them into the lookup table. This is kind of messy once the old table is out of the way tho.

Answer 1

1. Set the new table’s identity to be a non-identity field.
2. Modify either your data population procedures to populate the non-identity field on your new table with the old table’s identity value.
3. At cutover, switch your new field to auto-increment and set the seed number accordingly.