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From: marta@CS.UCLA.EDU
Newsgroups: comp.databases
Subject: Informix Lookup Joins
Message-ID: <11983@shemp.CS.UCLA.EDU>
Date: 5 May 88 18:35:31 GMT
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Reply-To: marta@CS.UCLA.EDU (Phoenix)
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Help!!!!!!!!!


I'm want to do something similar to using "Lookup Joins" but that
allows modification of the data.

I have two tables: *schedule* and *courses*.
Table *schedule* is a list of courses taught during the quarter;
the primary keys are attributes s_number and s_section 
[number and section of course]. The table *courses* is a list 
of courses offered by the department; the primary key is attribute 
c_number [the number of the course]. 

*schedule*				*courses*

s_number 				c_number
s_section				c_title
s_title					c_units
s_instructor				c_type (Lab, Lect, etc)
s_time					c_inst_charge
s_room

When I make an entry into the *schedule* table using a screen form,
I want the s_title attribute to be set equal to the c_title attribute
for the corresponding course number, i.e.:

 		if s_number = c_number then
			s_title := c_title

The effect should be that of providing default values for a field
(course title) depending on another field (course number).
As soon as the course number is entered in the table *schedule*
the course title is provided from the table *courses*
But, if the course title is not correct, I want to be able to modify it.
and store it in the table *schedule* (I do NOT want to modify
c_title).

The reason for this, (yes, there is a 'logical' explanation!) is that
we have graduate courses with a generic number (eg 299) which has
an official title of "Current Topics in Computer Science". The
real title changes everytime it is taught to, for example,
"Special Topics in High Speed Computing". If I required that the
title be entered every time a course is taught for every course, 
it would be a big hassle (lookup time, data entry time, error prone, etc.)
Any ideas? is this at all possible using Informix?

Thank you for your time.

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| Marta E. Cervantes  (213) 206-3321                          |
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