An example of comparison of two numbers using a searched CASE expression : CASE « PL SQL Statements « Oracle PL/SQL Tutorial

SQL>
SQL>
SQL> declare
  2    a number :=20;
  3    b number :=-40;
  4    string varchar2(50);
  5  begin
  6    string :=case
  7               when (a>b)then 'A is greater than B'
  8               when (a<b)then 'A is less than B'
  9             else
 10               'A is equal to B'
 11             end;
 12    dbms_output.put_line(string);
 13  end;
 14  /
A is greater than B

PL/SQL procedure successfully completed.

SQL>
SQL>

22.2.CASE
	22.2.1.	CASE statements
	22.2.2.	When creating selector CASE statements, you cannot have NULL in the list of possible values.
	22.2.3.	Use CASE statement
	22.2.4.	Named case block
	22.2.5.	case when
	22.2.6.	An example of comparison of two numbers using a searched CASE expression
	22.2.7.	Variable assignment with case statement
	22.2.8.	Use case statement in a dbms_output.put_line
	22.2.9.	Simple CASE statement with range
	22.2.10.	Case statement to call procedure
	22.2.11.	Return statement with case
	22.2.12.	Use case statement in procedure call to use the proper parameter value