DECODE & dual for DB2

DECODE from oracle
-- SELECT CASE MESE WHEN '02' THEN 'Febbraio' WHEN '03' THEN 'Marzo'
WHEN '04' THEN 'Aprile' ELSE 'Boh' END from MESI

Dual from Oracle is SYSIBM.SYSDUMMY1 for DB2
-- SELECT 'CIAO' FROm SYSIBM.SYSDUMMY1