Returning a value from a sub routine

cosmicsoup has asked for the wisdom of the Perl Monks concerning the following question:

Monks,

Can someone kindly instruct me on what I'm doing wrong here?

my $today = getMaxDate();

sub getMaxDate {

my $sqltoday;

my $SQLDT = qq(select max(convert(char(12), Modified_Date, 101)) from 
+Metrics);

my $dbhdt=Sybase::DBlib->dblogin($user, $pw, $server);
  $dbhdt->dbcmd($SQLDT);
  $dbhdt->dbsqlexec;
  $dbhdt->dbresults;

  while (@data = $dbhdt->dbnextrow) {
        $sqltoday = $data[0];
        }

return $sqltoday;

}
[download]

The value for $today is always empty!

Thanks!

Comment on Returning a value from a sub routine Download Code

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Re: Returning a value from a sub routine by dragonchild (Archbishop) on Nov 12, 2004 at 15:07 UTC
Some further suggestions: Don't use global variables. It would be better to create your $dbh outside the function and pass it in. Add 'use strict' and 'use warnings', then fix the stuff that pops up. I'd recommend shifting from Sybase::DBlib to DBI and DBD::Sybase. DBI is the standard for Perl database connections and is more portable. Being right, does not endow the right to be rude; politeness costs nothing. Being unknowing, is not the same as being stupid. Expressing a contrary opinion, whether to the individual or the group, is more often a sign of deeper thought than of cantankerous belligerence. Do not mistake your goals as the only goals; your opinion as the only opinion; your confidence as correctness. Saying you know better is not the same as explaining you know better.	[reply]
Re: Returning a value from a sub routine by Roger (Parson) on Nov 12, 2004 at 15:02 UTC
Your code does not specify which database to use on the sybase server. Most likely is that your connection succeeded, but defaults to the master database. A quick fix is to specify the name of the database in the $SQLDT like below: `select max(convert(char(12), Modified_Date, 101)) from databasename..Metrics` [download] Assumes that you are using ASE of course.	[reply] [d/l]
Re: Returning a value from a sub routine by ikegami (Patriarch) on Nov 12, 2004 at 14:53 UTC
I'd start by checking if the database query worked. Add some error checks.	[reply]
Re: Returning a value from a sub routine by gnu@perl (Pilgrim) on Nov 12, 2004 at 15:52 UTC
Also of note, the 'return $sqltoday' line will return the first element of the final line of your '$dbhdt->dbnextrow' query. For example if the data were like this: `Field1 Field2 Field3 bill smith 32 bob jones 43` [download] your return would be 'bob' If that final line had no value in the first position you would return nothing, like this: `Field1 Field2 Field3 bill smith 32 jones 43` [download] this would return '' in '$sqltoday'; Note, this is just a guess since I do not know your data setup. -Chad	[reply] [d/l] [select]