y $lon = -0.232323127347249;
my $sql = qq| SELECT lon,lat,location_id
                FROM lat_long
                WHERE lon>= $lon|;

my $sth = $sp->dbh->prepare($sql);
$sth->execute();
print STDERR "Rows not using placeholders ".$sth->rows."\n";
$sql = qq| SELECT lon,lat,location_id
                FROM lat_long
                WHERE lon >= ?|;
$sth = $sp->dbh->prepare($sql);
$sth->execute($lon);
print STDERR "Rows using placeholders ".$sth->rows."\n";