Help in Validations please.....

Question

Hi All,
I need your help in this.
I have 5 fields in my D2K form, namely ID, Start_date, End Date, Contract_type, Status.
The values in the table could be.
ID Start_date End Date Contract_type Status
NJ1 01-JAN-02 30-MAR-02 A Active
AB1 01-JAN-02 15-APR-02 B Active
CD2 15-FEB-02 20-JUN-02 A Active
NJ1 01-APR-02 15-JUN-02 A Active
NJ1 15-JUL-02 30-SEP-02 B Active
The condition is that for a particular ID (say NJ1), for a period defined by a start date and end date,
there will be only one active contract.
For example, if I add one more row for NJ1, with start date as 01-MAY-02, it should be invalid, because there is already
a contract active between 01-APR-02 and 15-JUN-02. So I have to check all the rows where ID ='NJ1' and the dates.
Can you please let me know how I can check this?
Your help will be greatly appreciated.
Thanks very much in advance.
Warm Regards,

Answer 1

hi,
write a backend procedure for this which accepts ur id and start date as parameters and have another out parameter to check wheter the record already exisits.now call this procedure from when-validate-item of ur start date.i think this should help u solve ur problem.
procedure check_date(vid in varchar2,sdate in date,fg out number)
is
begin
select count(id) into fg from table where sdate between start_date and end_date and id = v_id ;
end;
call this proc in when-validate-item and check if fg is zero means u dunno have any existing record else u have one.