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Re: Simple way of storing Access booleans (Yes/No) fields

From: "Philippe Lang" <philippe(dot)lang(at)attiksystem(dot)ch>
To: "Kevin Bailey" <kbailey(at)freewayprojects(dot)com>, <pgsql-odbc(at)postgresql(dot)org>
Subject: Re: Simple way of storing Access booleans (Yes/No) fields
Date: 2006-09-28 06:48:22
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Lists: pgsql-odbc

Firstly, don't forget to use an Access 2003 native format database in your project, and not an Access 2000 format database. There are huge slowups when using the Access 2000 format. Don't ask me why!

For your specific problem, I would personnaly use an int2, and treat on the server everything that is different from 0 as true. This is quick, and with a little work in PLPGSQL, it might be clean too. Otherwise, you might give a try to the advanced options of the ODBC driver: I'm not sure they can help, but it's worth trying.


Philippe Lang


	De : pgsql-odbc-owner(at)postgresql(dot)org [mailto:pgsql-odbc-owner(at)postgresql(dot)org] De la part de Kevin Bailey
	Envoyé : jeudi, 28. septembre 2006 00:22
	À : pgsql-odbc(at)postgresql(dot)org
	Objet : [ODBC] Simple way of storing Access booleans (Yes/No) fields
	PG version 7.4 and Access version 2003.
	Its the old Access boolean issue which needs as simple an answer as possible?
	I have a client where many users were running off the same Access database which obviously got corrupted and recently failed completely.
	After finding a backup the data has been moved to a Postgresql DB running on a Debian stable server.
	The data was exported via ODBC and I've tidied up the autonumber-to-sequence issue.  The original Access tables were renamed to tablebnname_old and the new Postgresql tables have been set up as linked tables with the original names.  Most of the application is working fine.
	Seems like only one issue remains.
	On a couple of forms there are check boxes and radio buttons which linked originally to Yes/No (i.e. Boolean) fields in the original Access table.
	I have a fairly free hand to sort this out - and there are only 4 tables which contain boolean fields and I can alter the Access application as I see fit.
	There are quite a few queries (dozens) but again I can ask them to cut them down and re-write needed queries if necessary.
	What is the simplest way forward?
	What should the ODBC connection be set as?
	Here are some possible scenarios.
	1. Should I set the fields to be int2 data type and then set the ODBC driver to not treat bools as char but treat -1 as true.  
	Will queries written in Access then run correctly?  I thought I'd tried this and it didn't work possibly because I did not relink the table.
	2. If I simply uncheck the treat bools as char option will the data be saved correctly as booleans - will the ODBC driver be ok with the data - i.e. reading and writing.
	3. Should I simply set the field as a char(1) and then in Access somehow or other set the check boxes to save the data as 't' or 'f'.  How would the control do with reading the data.
	4. I understand there may be some extra functions which may be added to PG to get Access play properly - is there a simple function which can be added.  Is there a well documented, proven and established method to acheive this.
	5. Have these methods been 'tried and tested'
	6. Change the check boxes to combo boxes - the form is horribly cluttered but the following seems like a simple answer.
	The way I have handled this is to avoid check boxes and use a combo box 
	instead. I supply the values as True;1 ,False;0 and bind the field to the 
	second value of each pair. To make things easier for data entry I hide the 
	second column by giving it a width of 0".  In my DSN settings I check bool as 
	char and uncheck true as -1. 
	Adrian Klaver	
	aklaver ( at ) comcast ( dot ) net

	There are however dozens of queries and many of them use booleans which then may not work - however, if needed I can ask the client to remove the unneeded queries and I could then re-write the existing queries to take into account the new field.
	Maybe I should create the field as int2 and in the combo box have the bound fields as -1 (label True) and 0 (label False).  Maybe this way the existing Access queries would work ok without changes?
	Any thoughts would be gratefully received.

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