I got it. I used CASE to solve this problem.

select ename from emp where ename= CASE
WHEN 'james' THEN '1'
WHEN 'king' THEN '2'
WHEN 'allen' THEN '3'
WHEN 'clark' THEN '4'
END in('1','2','3','4') order by CASE ename
WHEN 'james' THEN '1'
WHEN 'king' THEN '2'
WHEN 'allen' THEN '3'
WHEN 'clark' THEN '4'
END


Thanks for all