distinct clause in POST QUERY trigger in forms

[stecal]

Use

select dept_payin_no INTO DEPT_PAY from post_treasury_copy
where to_date(payin_date,'DD-MON-YY') = to_date(payin_date,'DD-MON-YY')
where rownum = 1

would work if you are sure you have one and only one value based on that date.