Confused about this query

[HMBeaty]

Hello again

So, I'm finally starting to learn how to add custom usergroup permissions, and have been somewhat successful (I think), however, in the install code for my modification, I first tried:

$db->hide_errors();

$db->query_write("ALTER TABLE " . TABLE_PREFIX . "usergroup
    ADD usmlsaperms int(10) unsigned NOT NULL default '0',
    ADD staffappminpostreq int(10) NOT NULL default '100',
    ADD staffappminrepreq int(10) NOT NULL default '100',
    ADD staffappminregreq int(10) NOT NULL default '100'
");

$db->show_errors();

...which didn't work. So, I went the long way and tried:

$db->hide_errors();

$db->query_write("ALTER TABLE " . TABLE_PREFIX . "usergroup
    ADD usmlsaperms int(10) unsigned NOT NULL default '0'
");
$db->query_write("ALTER TABLE " . TABLE_PREFIX . "usergroup
    ADD staffappminpostreq int(10) NOT NULL default '100'
");
$db->query_write("ALTER TABLE " . TABLE_PREFIX . "usergroup
    ADD staffappminrepreq int(10) NOT NULL default '100'
");
$db->query_write("ALTER TABLE " . TABLE_PREFIX . "usergroup
    ADD staffappminregreq int(10) NOT NULL default '100'
");

$db->show_errors();

....which seems to work so far.

So, my question is, why didn't the first code work?