SQL Server Stored Procedures: How to Efficiently Merge INSERT and UPDATE Operations?

Querying SQL Server: Merging Insert and Update in Stored Procs

Problem:

For efficiency, a stored procedure is sought that combines an update with an insert, only performing the insert if the record does not already exist.

Assumption:

The current approach is an update followed by an insert if the update affects zero rows. This is believed to be optimal because:

• An explicit select is avoided, reducing processing overhead.
• If the update is successful, no additional select is required.

Validation:

The assumption is correct. This method, known as upsert or merge, is indeed the most efficient way to combine an insert and update in a stored procedure.

Importance of Upsert:

Upsert minimizes reads by attempting an update and only inserting if the update affects zero rows. In most cases, the row already exists, requiring only a single I/O operation.

Considerations:

However, it is crucial to note that this pattern can have potential issues. For more information on these issues and a workaround, please refer to the following resources:

• [SQL Server: Upsert Anti-Patterns and Safe Alternatives](https://www.simple-talk.com/sql/t-sql-programming/sql-server-upsert-anti-patterns-and-safe-alternatives/)

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