MySQL - CREATE INDEX

CREATE UNIQUE INDEX IDIndex ON HeadOfState (ID);
CREATE INDEX NameIndex ON HeadOfState (LastName, FirstName);

With CREATE INDEX, it's necesary to provide a name for the index. With ALTER TABLE, MySQL creates an index name automatically if you don't provide one.

Unlike ALTER TABLE, the CREATE INDEX statement can create only a single index per statement. In addition, only ALTER TABLE supports the use of PRIMARY KEY.

Choosing an Indexing Algorithm:

CREATE INDEX id_idx USING BTREE ON lookup(id);