DBI placeholders - Mailing list pgsql-general

Hi everyone,


I'm wondering if someone could explain to me how placeholders work with
Perl DBI linking to Postgresql.  I seem to have trouble using them in a
loop.  For example, the code:

my $i = 0;
$sth = $dbh->prepare("UPDATE yeast1 set ? = '?' where yeast1.orf =
temp.orf");
while ($i<$#columns) {
    $sth->execute($i, $tables[$i-1];
    $i++;
}

This returns an error from the Pg parser.  Any suggestions?  Also, this
query is incredibly slow--does anyone have suggestions for optimization?

Thanks!
Evan