Path: utzoo!attcan!uunet!husc6!bloom-beacon!tut.cis.ohio-state.edu!mandrill!hal!ncoast!allbery
From: allbery@ncoast.UUCP (Brandon S. Allbery)
Newsgroups: comp.databases
Subject: Re: Informix Lookup Joins
Message-ID: <7782@ncoast.UUCP>
Date: 15 May 88 21:40:16 GMT
References: <11983@shemp.CS.UCLA.EDU>
Reply-To: allbery@ncoast.UUCP (Brandon S. Allbery)
Followup-To: comp.databases
Distribution: na
Organization: Cleveland Public Access UN*X, Cleveland, Oh
Lines: 46

As quoted from <11983@shemp.CS.UCLA.EDU> by marta@CS.UCLA.EDU:
+---------------
| I'm want to do something similar to using "Lookup Joins" but that
| allows modification of the data.
| 
| 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).
+---------------

We do this by creating a special screen of display-only fields after all the
data entry screens; doing the "lookup joining" into the display-only fields
on that screen; then using something like:

	before editadd editupdate of s_number
		let x001 = f022

	after editadd editupdate of s_number
		if x001 != f022 then
			let f023 = x002

where "f023" is the s_title field and the lookup is coded like:

	f022 = s_number, lookup x002 = c_title joining *c_number;

(This is Informix 3.3 syntax, it may vary slightly for Informix-SQL.)  That
lets us assign the initial s_title and then change it if we want.

The save and test against the original value of f022 is needed so that the
s_title isn't forced back to the c_title value when you press RETURN on the
field without entering anything.
-- 
	      Brandon S. Allbery, moderator of comp.sources.misc
	{well!hoptoad,uunet!marque,cbosgd,sun!mandrill}!ncoast!allbery
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