Using the IF-THEN_ELSE Statement for Conditional Control in PL/SQL

The IF-THEN-ELSE statement lets you execute a sequence of statements conditionally.

An IF statement looks like:
IF THEN ELSE END IF;
The ELSE part is optional. If you want a multiway branch, use:
IF THEN ...
ELSIF THEN ...
... ...
ELSIF THEN ...
ELSE ...
END IF;