What does the KEY keyword mean?

Stan picture Stan · May 29, 2009 · Viewed 111.2k times · Source

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?

Answer

MartinodF picture MartinodF · May 29, 2009

Quoting from http://dev.mysql.com/doc/refman/5.1/en/create-table.html

{INDEX|KEY}

So KEY is an INDEX ;)