Using if logic in the where clause of a select statement

Question

I have a select clause. And in the select clause there is a variable all_off_trt that can be 'Y' or 'N'.
In the where clause I want to make it so that if a form variable is checked and all_off_trt is 'Y' then
exclude it else if the form variable isn't checked then select it no matter what all_off_trt is.
Is there any way to include either and if statement or a case statement within the where clause to acheive this? If not is there another way of doing it?
Basically I am looking for a case statement like this
case
when all_off_trt = 'Y' and mail_para.code = 'Y' then false
else true
end
Message was edited by:
Tugnutt7

Answer 1

Ok, so that really doesn't solve my problem. I have 3 different fields that I need to do that with. Each combining in a select statement to print an email list, as well as other thing limiting the where clause.
This is currently what I have, tested and working 100%.
cursor email_cur is
     select unique p.email,s.all_off_trt,s.all_deceased,s.no_enroll
from participant p, trialcom t, ethics s
where p.status='A'
and p.surname=t.surname
and p.initials=t.initials
and s.trial_cd = t.tricom
and s.centre = t.centre
and p.email is not null
and (t.centre in (select code from mail_parameters where user_name=user and mail_para='CENTRE')
or 'XX' in (select code from mail_parameters where user_name=user and mail_para='CENTRE'))
and (t.tricom in (select code from mail_parameters where user_name=user and mail_para='TRIAL')
or 'XX' in (select code from mail_parameters where user_name=user and mail_para='TRIAL'))
and (t.role in (select code from mail_parameters where user_name=user and mail_para='ROLE')
or 'XX' in (select code from mail_parameters where user_name=user and mail_para='ROLE'))
and (p.country in (select code from mail_parameters where user_name=user and mail_para='COUNTRY')
or 'XX' in (select code from mail_parameters where user_name=user and mail_para='COUNTRY'))
and (t.represent in (select code from mail_parameters where user_name=user and mail_para='REPRESENT')
or 'XX' in (select code from mail_parameters where user_name=user and mail_para='REPRESENT'));
This is in a program unit that runs when a button is clicked. At the end of that I need to add on the 3 case statements that help further narrow down the selection of emails to be printed. Then it prints the emails selected from this statement into a file. So it has to be done right in the select statement. The three table variables are the all_off_trt, all_deceased, and no_enroll. The form has 3 checkboxes. One for each, that when checked (giving the variable associated with the checkboxes a value of 'Y') excludes all emails that have a 'Y' in the coresponding table variable.