CASE & DECODE

CASE
SELECT deptno
,    CASE deptno WHEN 1 THEN 'ONE'
        WHEN 2 THEN 'TOW'
      ELSE 'OTHER'
END as "DEPT NAME"
FROM emp;

DECODE
SELECT deptno, DECODE(deptno,'1','ONE','2','TWO') as "DEPT NAME"
FROM emp;