PL/SQL exception handling: do nothing (ignore exception)

While I agree that 99% of the time it is bad practice to silently ignore exceptions without at least logging them somewhere, there are specific situations where this is perfectly acceptable.

In these situations, NULL is your friend:

[...]EXCEPTION    WHEN OTHERS THEN        NULL;END;

Two typical situations where ignoring exceptions might be desirable are:

1) Your code contains a statement which you know will fail occasionally and you don't want this fact to interrupt your program flow.In this case, you should enclose you statement in a nested block, as the following example shows:

CREATE OR REPLACE PROCEDURE MY_PROCEDURE() IS    l_empoyee_name  EMPLOYEES.EMPLOYEE_NAME%TYPE;BEGIN    -- Catch potential NO_DATA_FOUND exception and continue    BEGIN         SELECT EMPLOYEE_NAME        INTO l_empoyee_name        FROM EMPLOYEES        WHERE EMPLOYEE_ID = 12345;    EXCEPTION        WHEN NO_DATA_FOUND THEN            NULL;        WHEN OTHERS THEN            RAISE;    END;    do_stuff();EXCEPTION    WHEN OTHERS THEN        -- Propagate exception        RAISE;END;

Note that PL/SQL generally does not allow for the On Error Resume Next type of exception handling known from Visual Basic, where all exceptions are ignored and the program continues to run as if nothing happened (see On error resume next type of error handling in PL/SQL oracle). You need to explicitly enclose potentially failing statements in a nested block.

2) Your procedure is so unimportant that ignoring all exceptions it throws will not affect your main program logic. (However, this is very rarely the case and can often result in a debugging nightmare in the long run)

BEGIN    do_stuff();EXCEPTION    WHEN OTHERS THEN        -- Ignore all exceptions and return control to calling block        NULL;END;

Another scenario when it does make sense to silently ignore exception:When you call a script that is expected to create an object if it does not exist, and you do not have a create-or-replace syntax for that object. PLSQL objects have a create-or-replace syntax, but tables and indexes do not. Then we can put such scripts in a block and ignore the raised exception.