To ensure that the data normalized into these supporting tables is not duplicated, a unique index should be created on each of the text fields in each of those four supporting tables. Write four ALTER TABLE or CREATE UNIQUE INDEX statements to add these unique indexes. Note that while the "page" column in the "log$\_$pages" table will have a unique index, the "filetype" column will not.

SQL$,$ log$\_$areas:

SQL$,$ log$\_$clients:

SQL$,$ log$\_$pages:

SQL$,$ log$\_$referers: