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

In Postgresql 8.0 I wrote the following functions, which will
probably work in 7.4 as well.
They have removed the bool problem completely. My ODBC settings are:
Bools as Char UNCHECKED
TRUE is -1 UNCHECKED

I am using Access 2000, with a lot of checkboxes and boolean fields in
the front end with no problems

Sim
set search_path=pg_catalog;

create or replace function inttobool(num int,val bool) returns bool as
$$
begin
if num=0 and not val then
return true;
elsif num<>0 and val then
return true;
else return false;
end if;
end;
$$ language 'plpgsql';
create or replace function inttobool(val bool, num int) returns bool as
$$
begin
return inttobool(num,val);
end;
$$ language 'plpgsql';
create or replace function notinttobool(val bool, num int) returns bool as
$$
begin
return not inttobool(num,val);
end;
$$ language 'plpgsql';
create or replace function notinttobool(num int, val bool) returns bool as
$$
begin
return not inttobool(num,val);
end;
$$ language 'plpgsql';

CREATE OPERATOR = (
leftarg = integer,
rightarg = boolean,
procedure = inttobool,
commutator = =,
negator = !=
);
CREATE OPERATOR = (
leftarg = boolean,
rightarg = integer,
procedure = inttobool,
commutator = =,
negator = !=
);
CREATE OPERATOR <> (
leftarg = integer,
rightarg = boolean,
procedure = notinttobool,
commutator = <>,
negator = =
);
CREATE OPERATOR <> (
leftarg = boolean,
rightarg = integer,
procedure = notinttobool,
commutator = <>,
negator = =
);

________________________________________________________________________________

Hi,

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'

http://www.mail-archive.com/pgsql-docs(at)postgresql(dot)org/msg01563.html
http://community.seattleserver.com/viewtopic.php?p=8 sid=3add118a6924da03531fcbbbcc2c3ca8
http://www.mrayyan.com/?p=42

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.

Kevin