Creating composite key in mnesia

Question

How to create a composite key(key with combination of two attributes) in mnesia table.As far as i know is that the first element in record which we use to create mnesia table is primary key.Please expain with simple example

Answer 1

For example, when use this record

-record(cuser, {id,login_id,email}).

to create mnesia table, then the primary key is id, but when you change this recode to this:

-record(cuser, {{id,login_id},email}).,

then the primary key is {id,login_id}.

You can use an tuple as the primary key.