If you are using mysql for your db server then I suggest you use MySQL-Front. It is a great little admin tool that makes creating indexes, and anything else for that matter, simple through a GUI.
You need to add a UNIQUE index to column "NAME", something like this -
sql statement - "CREATE UNIQUE INDEX ON tbl_name (NAME);"
- where "tbl_name" is the name of the table containing the field "NAME".
Download MySQL-Front here
Hope this helps 😉