SQL & PL/SQL

Hi Team

i have a scenario like a region EMEA we need to show the data of EMEA if the user enters all then need to display full data in a table.

CREATE TABLE EMP_2(REGION VARCHAR2(22));
INSERT INTO EMP_2 VALUES('EMEA');
INSERT INTO EMP_2 VALUES('APJC');
INSERT INTO EMP_2 VALUES('AMERICAS');
---I try using decode not working
SELECT 
  DECODE(REGION,'EMEA','EMEA','APJC','APJC','AMERICAS','AMERICAS','ALL') FROM EMP_2
WHERE 
  DECODE(REGION,'EMEA','EMEA','APJC','APJC','AMERICAS','AMERICAS','ALL') = 'ALL'
;

can some give some idea on this..