select a particular group in a column using php

i created a table in database.I have named column called groups where member can register for group 1, group 2, group 3...

I want to be able to show members of group one or group two or group 3 only. Group 1 member can only see group 1 members if login into client side? and i want to limit the max number of group members to 3. group 1 = 3 members only Will need advice on this issue thanks.

my sql table

CREATE TABLE IF NOT EXISTS accounts ( id int(11) NOT NULL AUTO_INCREMENT, studentid int(9) NOT NULL, password varchar(255) NOT NULL, email varchar(100) NOT NULL, groups varchar(100) NOT NULL, PRIMARY KEY (id) ) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8;