PL/MySQL

PROBLEM:
First line of code just will not work for me. It does not make the column unique and allows for duplicates. WHY????? Can anyone tell me where I am going wrong??????? Thanks in advance.

CODE:
$dbh->do("CREATE UNIQUE INDEX idx_name ON t0(name)");
$dbh->do("DELETE FROM t0");
my $loop = 0;
foreach $key (keys(%FORM))
{
$loop += $loop + 1;
print "$key = $FORM{$key}<br>";
my $val = $FORM{$key};
$dbh->do("INSERT INTO t0 VALUES ($loop, '$val')");
}
$dbh->do("DELETE FROM t0 WHERE name < '0'");

my $sth = $dbh->prepare("SELECT pk, name FROM t0");
$sth->{"mysql_use_result"} = 1;
$sth->execute();
my $numFields = $sth->{'NUM_OF_FIELDS'};
print $numFields;
my $names = $sth->{'NAME'};
print '<select name=Choice>';

while (my $ref = $sth->fetchrow_arrayref)
{
for (my $i = 0; $i < $numFields; $i++)
{

if ($i)
{
printf ("%s</option>",$$ref[$i]);
}
else
{
printf ("<option value=%s>",$i);
}
}
print '<br>';
}

print '</select><br><br>';

$dbh->disconnect();

you should check that the index is actually being created, incase that's the problem

$dbh->do("CREATE UNIQUE INDEX idx_name ON t0(name)") or die ('Error creating index', $dbh->errstr);

i tried out your suggestion:

$dbh->do("CREATE UNIQUE INDEX idx_name ON t0(name)") or die ('Error creating index', $dbh->errstr);

I only get a blank screen.

when i don't include the 'or die........' part the code carry's on but it allows for duplicates.

if you put this after use DBI;
use CGI::Carp qw(fatalsToBrowser);

it should print out the error message on the browser

Thanks
I used
use CGI::Carp qw(fatalsToBrowser);

and this what it keeps telling me

Error creating indexDuplicate key name 'idx_name' at 0.cgi line 31.

I changed the name of the index to something i know is not in the database eg.butterfly, sky etc. and it still gives me that error.

do you have any idea why???

Thanks for all your help. :)

Forget last message. It works now when I use the following code:-
use CGI::Carp qw(fatalsToBrowser);

$dbh->do("ALTER TABLE t0 MODIFY name CHAR(255) NOT NULL") or die('Error creating modify', $dbh->errstr);
$dbh->do("ALTER TABLE t0 ADD UNIQUE (name(6))") or die ('Error creating index', $dbh->errstr);

THANKS for all your help. You were tremendous.

Just a note, PL/SQL is a procedural language used by the Oracle database, it has nothing to do with perl.. Maybe you should refer to perl and mysql as perl/mysql to prevent confusion.