NULL STATEMENT

Usually when you write a statement in a program, you want it to do something. There are cases, however, when you want to tell PL/SQL to do absolutely nothing, and that is where the NULL comes.

The NULL statement deos nothing except pass control to the next executable statement.

You can use NULL statement in the following situations.

Ø  Improving program readability.

Sometimes, it is helpful to avoid any ambiguity inherent in an IF statement that doesn’t cover all possible cases. For example, when you write an IF statement, you do not have to include an ELSE clause.

Ø  Nullifying a raised exception.

When you don’t want to write any special code to handle an exception, you can use the NULL statement to make sure that a raised exception halts execution of the current PL/SQL block but does not propagate any exceptions to enclosing blocks.

Ø  Using null after a label.

In some cases, you can pair NULL with GOTO to avoid having to execute additional statements. For example, I use a GOTO statement to quickly move to the end of my program if the state of my data indicates that no further processing is required. Because I do not have to do anything at the termination of the program, I place a NULL statement after the label because at least one executable statement is required there. Even though NULL deos nothing, it is still an executable statement.