|PL/SQL User's Guide and Reference
10g Release 1 (10.1)
Part Number B10807-01
NULL statement is a no-op: it passes control to the next statement without doing anything. In the body of an
IF-THEN clause, a loop, or a procedure, the
NULL statement serves as a placeholder. For more information, see "Using the NULL Statement".
NULL statement improves readability by making the meaning and action of conditional statements clear. It tells readers that the associated alternative has not been overlooked: you have decided that no action is necessary.
Certain clauses in PL/SQL, such as in an
IF statement or an exception handler, must contain at least one executable statement. You can use the
NULL statement to make these constructs compile, while not taking any action.
You might not be able to branch to certain places with the
GOTO statement because the next statement is
END IF, and so on, which are not executable statements. In these cases, you can put a
NULL statement where you want to branch.
NULL statement and Boolean value
NULL are not related.
In the following example, the
NULL statement emphasizes that only salespeople receive commissions:
IF job_title = 'SALESPERSON' THEN compute_commission(emp_id); ELSE NULL; END IF;
In the next example, the
NULL statement shows that no action is taken for unnamed exceptions:
EXCEPTION ... WHEN OTHERS THEN NULL;