What is bad in "When Others Then Null" in PL/SQL?

Question

I just read this question, and a solution states that:

The fact that you don't know you got the NO_DATA_FOUND exception suggests that you have made one of the biggest errors PL/SQL developers ever make:

EXCEPTION
    -- Never do this in real code!!!
   WHEN OTHERS THEN NULL;
END;

Could you explain me what is the error in this statement and what would you do to avoid doing that...

Answer 1

The problem is, that you are catching all exceptions, and then ignoring them. You'll never know when something went wrong.

Answer 2

There's nothing wrong with this snippet of code if you don't want the pl/sql block's exception to propagate any further for example. If you do it on purpose, it's not bad code or a mistake. That's the catch all in pl/sql. And there might be situations in code where you have nested BEGIN/EXCEPTION/END blocks and one might not want the transaction to fail just if a particular cross section of code fails. You can't state it's bad coding if you do it intentionally for whatever reason/requirement.

BEGIN

  --something important here

  --something even more important here

  BEGIN
    --something secondary goes here but not important enough to stop the process or
    --log a message about it either
    --maybe send an informative email to the support group or 
    --insert a log message when debugging the process or
    --the list could go on and on here
  EXCEPTION
    --I don't care if this block fails, absorbing all errors regardless of type
    WHEN OTHERS THEN NULL;
  END;

  -- something super important here, must happen

EXCEPTION
  WHEN NO_DATA_FOUND THEN 
    -- do something useful for this exception
  WHEN OTHERS THEN
    -- do something by default if we don't expect this error
END;