PL/SQL: "IF ... ELSEIF" constructs should end with "ELSE" clauses

This rule applies whenever an IF statement is followed by one or
more ELSEIF statements; the final ELSEIF should be followed by an ELSE statement.

The requirement for a final ELSE statement is defensive programming.
The ELSE statement should either take appropriate action or contain
a suitable comment as to why no action is taken. This is consistent with the
requirement to have a final ELSE clause in a CASE
statement.

Noncompliant Code Example

IF my_variable = 0 THEN
  do_something;
ELSIF my_variable = 1 THEN
  do_something_else;
END IF;

Compliant Solution

IF my_variable = 0 THEN
  do_something;
ELSIF my_variable = 1 THEN
  do_something_else;
ELSE
  -- Nothing has to be done.
  NULL;
END IF;