Re: nested if , and how to trigger....

Hi,

> > create table tb (
> > code varchar(4),
> > classes varchar(6),
> > lecture varchar(4),
> > th int2,
> > day varchar(1),
> > hr varchar(1),
> > room varchar(4),
> > primary key (code,kl,ds));
>
> code,kl,ds?  What are kl and
> ds?
sorry, it should be code,classes,and lecture

>
> > my questions is how to prevent this record to be insert:
> > code     classes  lecture      th         day   hr     room
> > K021    1tip01   1011        5          1      1      1111
> > K022    1tip01   1011        5          1      1      1111
> >
> > or :
> > code     classes  lecture      th         day   hr     room
> > K021    1tip01   1011        5          1      1      1111
> > K021    1tip01   1012        5          1      1      1111
>

code is for the subject that lecture teach on the class
what i really want to do is how to prevent:
1. different subject will not be give at same time (day and hr), same room
2. different lectures with same subject will not be at same time and room
too
3. but one lecture can teach same subject in different classes at same time
and room
TIA
Didi