In this MySQL table definition:
CREATE TABLE groups (
ug_main_grp_id smallint NOT NULL default '0',
ug_uid smallint default NULL,
ug_grp_id smallint default NULL,
KEY (ug_main_grp_id)
);
What does the KEY
keyword mean? It's not a primary key, it's not a foreign key, so is it just an index? If so, what is so special about this type of index created with KEY
?
Quoting from http://dev.mysql.com/doc/refman/5.1/en/create-table.html
{INDEX|KEY}
So KEY
is an INDEX
;)