select MIN(mi), MAX(ma)
from(
SELECT
(case when (ROWNUM /2) like'%.5' then INVOICENO end ) as mi ,
(case when (ROWNUM /2)not like'%.5' then INVOICENO end ) as ma,
trunc(ROWNUM /2 -0.5) as stt
FROM (
select 'N' ISHASNEXTINVOICENO, INVOICECOLLECTION_NO, INVOICESIGN,MIN(INVOICENO) as INVOICENO from HIS_INVOICE
WHERE INVOICENO IS NOT NULL
--AND  INVOICESIGN != 'AA/16P'
--and CREATED > sysdate-30
GROUP BY INVOICECOLLECTION_NO, INVOICESIGN
UNION
select nvl((select 'Y' from his_invoice sub where iv.INVOICECOLLECTION_NO = sub.INVOICECOLLECTION_NO and sub.INVOICESIGN = iv.INVOICESIGN and iv.INVOICENO + 1 = sub.INVOICENO GROUP BY INVOICECOLLECTION_NO, INVOICESIGN,INVOICENO) , 'N') ISHASNEXTINVOICENO,
iv.INVOICECOLLECTION_NO, iv.INVOICESIGN, iv.INVOICENO from (select INVOICENO,INVOICECOLLECTION_NO,INVOICESIGN from HIS_INVOICE GROUP BY INVOICECOLLECTION_NO, INVOICESIGN,INVOICENO ) iv
WHERE iv.INVOICENO IS NOT NULL
--AND  iv.INVOICESIGN != 'AA/16P'
--and iv.CREATED > sysdate-30
GROUP BY iv.INVOICECOLLECTION_NO, iv.INVOICESIGN,iv.INVOICENO )
where ISHASNEXTINVOICENO ='N'
ORDER BY ISHASNEXTINVOICENO, INVOICESIGN, INVOICENO)
GROUP BY stt
ORDER BY stt;