users2group table

The Users 2 Group table is a join table - M2M relationship between the Group and Users table. It also has a pivot of permission.

The structure is highlighted below

CREATE TABLE `user2group` (
  `id` int(11) unsigned NOT NULL AUTO_INCREMENT,
  `groupid` int(11) unsigned NOT NULL,
  `userid` int(11) unsigned NOT NULL,
  `perm` varchar(128) DEFAULT NULL COMMENT 'admin: administrator; moderator: moderator; user:user',
  PRIMARY KEY (`id`),
  KEY `u2u` (`userid`),
  KEY `g2g` (`groupid`),
  CONSTRAINT `g2g` FOREIGN KEY (`groupid`) REFERENCES `group` (`id`) ON DELETE NO ACTION ON UPDATE NO ACTION,
  CONSTRAINT `u2u` FOREIGN KEY (`userid`) REFERENCES `users` (`id`) ON DELETE NO ACTION ON UPDATE NO ACTION
) ENGINE=InnoDB DEFAULT CHARSET=latin1;