use Sybase::DBlib;
use FileHandle;

my $dbh = new Sybase::DBlib 'lthomas', 'lthomas', 'HKT_ERCC';

######################
# I'm not familiar with Sybase, but can you prepare the dbh query?
# That would clean up the following section
######################

$dbh->dbuse('er_cc');
$dbh->dbcmd("exec sp_client_csv \"$month1\",\"$FORM{'cboDay1'}\",\"$FORM{'cboYear1'}\",\"$month2\",\"$FORM{'cboDay2'}\",\"$FORM{'cboYear2'}\"");
$dbh->dbsqlexec;
$dbh->dbresults;

open (FILE, ">client.csv") or die ("Couldn't open output file to write: $!");

#####################
# FYI your original post has a semi-colon after the while statement and before the '{'.
# Is that in your real code?
#####################

while (@xgdat = $dbh->dbnextrow(1)) { 
	print FILE join (',', @xgdat), "\n"; 
 }
close FILE or die ("Couldn't close output file: $!");