A Decode Statement

,select DECODE(NVL(v.dest_time, ''),'', NVL (m.dest_time, ''),v.dest_time) STIME,

from master m detail v where m.id=d.id

SELECT TRANSACTIONTYPE transtype, decode(TRANSACTIONTYPE,'C','Cheque','D','DD','I','Internal transfer','B',Decode(VOUCHERTYPE,'P','Direct Debit','Direct Credit'),'S','Cash') TRANSACTIONTYPE
from cb_voucher_info;