gistfile1.pl

$DBversion = '3.03.00.xxx';                                                                                                
if (C4::Context->preference("Version") < TransformToNum($DBversion)) {                                                     
    my $sth = $dbh->prepare("SHOW INDEX FROM items WHERE KEY_NAME = 'itemsstocknumberidx'");
    $sth->execute();
    if (my $index = $sth->fetchrow_hashref()){
      $dbh->do("ALTER TABLE `items` DROP INDEX `itemsstocknumberidx`;");                                                     
    }
    else {
      dbh->do("ALTER TABLE `items` DROP INDEX `itemstocknumberidx`;");
    }
    $dbh->do("ALTER TABLE items ADD INDEX itemstocknumberidx (stocknumber);");                                             
    print "Upgrade to $DBversion done (Change items.stocknumber to be not unique)\n";                                      
    SetVersion ($DBversion);                                                                                               
}