Hi monkfan, you missed to quote the $go_term, it should be:

my $sql = "SELECT Symbol FROM gene_info RIGHT JOIN gene2go ON(gene_inf
+o.GeneID=gene2go.GeneID) WHERE GO_Term='$go_term'";
[download]

Or, the best way as can be found in the excellent manual of DBI is to use a placeholder (the ? mark).

my $go_term = 'proteasome localization';
my $sql = 'SELECT Symbol FROM gene_info RIGHT JOIN gene2go ON(gene_inf
+o.GeneID= gene2go.GeneID) WHERE GO_Term=?';

my  $sth = $dbh->prepare($sql);
$sth->execute($go_term) or die "SQL Error: $DBI::errstr\n";
[download]

Then you don't need to worry about quoting anymore. Oh, another thing. Get used to use single quote on plain string, e.g it doesn't contain variable or evaluable expression.

---

Update: gleh, fixed typo