Extracting data from an Ms ACCESS query

[blackadder]

[Joost]

Hmm... it looks to me that you should read up on database design and SQL. You can solve it like this in Perl, but I wouldn't. Oh and I would use DBD::ODBC instead, so your code would be a bit more portable.

I'd make several tables for business_unit, group, subgroup and application, referering to each other where appropriate. and a cross table between subgroup and application.

Then do something like:

my $result = $dbh->selectall_arrayref(
   "SELECT application.name FROM application, group, subgroup, app_sub
+group WHERE
   application.id =  app_subgroup.application AND 
   app_subgroup.subgroup = subgroup.id AND
   subgroup.group = group.id AND group.name='Procurement'"
);
foreach (@$result) {
   print @$_;
}

With the current model it would look like:

my $result = $dbh->selectall_arrayref(
   "SELECT DISTINCT(application) FROM table_name WHERE
   group_name='Procurement'"
);
foreach (@$result) {
   print @$_;
}

Which is simpler, but will get you in trouble later on when your table starts getting bigger and bigger and people start spelling Internet Explorer as "Internt Explorer".

[blackadder]

[Joost]

I used DBI style method calls for running the sql, you need to find an equivalent method call for the ODBC module you are using. (Maybe $dbh->Sql ? I don't know, I don't use windows)

[blackadder]

[McMahon]

Win32::ODBC tanked early for me. When I sent email to Dave Roth, I got this back:

"To be honest we have not dealt with Win32::ODBC for several years now.
Most users are migrating to use DBI and the DBD::ODBC modules instead.
Since our perl projects are unfunded we have very little time to devote to them.
If you want to explore this further the source code for Win32::ODBC is on our FTP site. "

I've been using DBI ever since.

[periapt]

You've made a good start. $Hydra_db, at this point, contains a reference to the ODBC connection structure and not the results of the query itself. One issue you have is that the Sql statement from WinODBC returns the SQL error number or false if there was not error. Thus, in your code, the if statement block will run only if there is an error. Try this code instead.

if($Hydra_db->Sql("SELECT * FROM $qry")){
    print "SQL Error: ".$Hydra_db.Error()."\n";
}

Now, once you have a successful query, you need to retrieve the results. This is achieved in two steps. Step 1, fetch the row from the ODBC recordset. Step 2, move the contents of the row into a variable. I usually do it this way.

if($Hydra_db->Sql("SELECT * FROM $qry")){
    print "SQL Error: ".$Hydra_db.Error()."\n";
}else{
    # keep retrieving rows until nothing is left
    while($Hydra_db->FetchRow()){
        # pull one record into a variable for use       
        @groupapps = $Hydra_db->Data(); 
        print @groupapps,"\n";
    }
}

You can also pull the data into a hash. I'm not aware of any pod or other freely available doc that covers Win32 ODBC-maybe another Monk has a suggestion-but Dave Roth's Win32 Perl Programming: The Standard Extentions, 2nd Ed and Martin Brown's Active Perl Developer's Guide are two books that provide a lot of useful information on using Win32ODBC.