Date validation in a master/detail view

Question

Hi everyone,
I have a problem and I hope someone can help me. I'm trying to create a validation for my application. I have a Master/Detail view where I add rows to my database and in the rows there is a "from date" and "to date". I want to create a validation so that the "from date" can not be chosen before the current date.
I'm having trouble because most of the tutorials I read on this work with page items, but since I have this in a Master/Detail view I have Column Attributes, wich do not behave the same way as page items.
Any help would be very appreciated.
Thanks,
Luka

Answer 1

I'm still having quite some trouble with this... everything I try gives me some sort of error.
My latest attempt was to make a PL/SQL returning boolean validation with the code:
FOR i IN 1..APEX_APPLICATION.G_F10.COUNT LOOP
IF DATUM_OD(APEX_APPLICATION.G_F10(i), 'DD.MM.YYYY HH24:MI') < SYSDATE THEN
return true;
else
return false;
END IF;
END LOOP;
and it says:
Error processing validation.
ORA-06550: line 2, column 4: PLS-00201: identifier 'DATUM_OD' must be declared ORA-06550: line 2, column 1: PL/SQL: Statement ignored