Thanks Scott , Make sense in the oracle code is basically saying 
to_char(SYSDATE, 'MM') between '01' and '03') AND ---Oracle ----------> first quarter
--( to_char(EH.EFFDT, 'MM') between '10' and '12') AND ---Oracle between Oct-Dec
-- ( to_char(EH.EFFDT, 'YYYY') = (to_char(sysdate,'YYYY') - 1)) ) ---Oracle ----Previous year