Working with Identity Columns in SQL Server: Best Practices and Workarounds

2024-06-27

There are a few alternative approaches to achieve what you might be aiming for:

  1. Delete and Re-insert: If you need to modify a specific identity value, you can delete the row and then re-insert it with the desired value. However, this disrupts the natural sequence of the identity column and might cause issues with foreign key relationships.

  2. SET IDENTITY_INSERT ON: This is a temporary option that allows you to specify the identity value during insert operations. You can enable this setting within your INSERT statement, insert your data with the preferred identity value, and then disable it afterward. Keep in mind, this approach also disrupts the automatic sequencing.

  3. Reseed the Identity Column: You can use the DBCC CHECKIDENT command to adjust the seed value (starting point) for the identity column. This won't modify existing values, but it will affect the sequence of new identities generated after the change.

  4. Recreate the Identity Column: As a last resort, you can drop the identity column and recreate it with the desired seed and increment values. This approach requires careful consideration as it involves altering the table structure and potentially affecting dependent objects.

Important points to remember:

  • Modifying identity columns can have unintended consequences, so proceed with caution.
  • Consider if there are alternative ways to achieve your goal without manipulating identity values directly.
  • Always back up your database before making any significant changes.

For further details and examples, you can search for "https://stackoverflow.com/questions/889855/identity-column-in-sql-server" or "https://learn.microsoft.com/en-us/answers/questions/1107164/how-to-alter-column-in-sql".




Delete and Re-insert (Not recommended due to sequence disruption):

-- Assuming your table is named 'Products' and has an identity column 'ProductID'
DELETE FROM Products WHERE ProductID = 10;

INSERT INTO Products (ProductName, Price)
VALUES ('Headphones', 49.99);

UPDATE Products SET ProductName = 'Wireless Headphones' WHERE ProductID = 10;

SET IDENTITY_INSERT ON (Temporary for specific insert):

SET IDENTITY_INSERT Products ON;

INSERT INTO Products (ProductID, ProductName, Price)
VALUES (50, 'New Monitor', 199.99);

SET IDENTITY_INSERT Products OFF;

Reseed the Identity Column (Adjusts starting point):

DBCC CHECKIDENT ('Products', RESEED, 200); -- Sets seed to 200 for future inserts



  1. Add a Separate Non-Identity Column:
  • Introduce a new column (e.g., "CustomID") that isn't an identity column.
  • You can manage this column manually or through application logic to assign unique identifiers.
  • This keeps the automatic sequencing of the identity column intact while providing an additional way to reference data.
  1. Leverage Foreign Keys:
  • If you need to establish relationships between tables, utilize foreign keys instead of relying solely on identity values.
  • Foreign keys create referential integrity, ensuring data consistency across linked tables.
  • This approach promotes better database design and reduces dependence on identity column manipulation.
  1. Use Natural Ordering:
  • If the order of data in the table itself holds significance, consider using a natural ordering approach.
  • You can sort or filter data based on existing columns that represent a logical sequence.
  • This might not be suitable for all scenarios, but it's a viable option when order is inherent to the data.
  1. Create a Separate Sequence Table (For Complex Scenarios):
  • In specific cases, you might explore creating a separate table to generate unique sequences.
  • This table would have a single identity column and potentially additional columns for metadata.
  • Your application logic would then retrieve sequence values from this table and assign them to the main table during insert operations.
  • This approach offers more flexibility but requires additional development and maintenance effort.

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Giving Your Tables a Unique Makeover: Alternative Ways to Implement Identity in SQL Server

Here are some alternative approaches to achieve a similar outcome:Drop and Recreate the Column: This method involves temporarily removing the existing column using ALTER TABLE DROP COLUMN