How can I make UPDATE to return an error if no rows are affected in Postgresql?

Question

In my application code, I have an ordinary UPDATE statement to update some row's properties. However, I've encountered a bug where this statement was provided with an incorrect ID and no row was affected.

This bug was silent because UPDATE statement that affects no rows still finishes successfully. I want to prevent such bugs in the future, and to do so, I want to instantly and loudly fail if this happens. One option that I have is to include a RETURNING statement and check it in the application code, but before going with it (and updating the whole application codebase where this pattern occurs — which is a massive change), I wanted to check the alternatives.

Is there a way to write an UPDATE statement in such a way that it produces an error if now rows are affected?

Answer 1

It would be possible to put the UPDATE into a CTE and then do something with the number of results:

WITH cte AS (
  UPDATE ...
  RETURNING ...
)
SELECT 1 / COUNT(*) FROM cte;

If the division by zero is too obscure for you, write a function that raises a proper error.

Personally, I would use a plain UPDATE, and then in my application, wrap all such SQL calls in a function that checks the number of rows. (PG returns that number from every UPDATE, but not every database driver supports this.)