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databaseerlangmnesia

How to write "in" query for Erlang mnesia?

I have a mnesia table, lets say employee. I need to find all employee records whose name is in EmployeeNameList = ["Erlich", "Richard", "Gilfoyle", "Dinesh"]. Is there a way to do this using mnesia:select or other function?

Solution

  • Following the documentation of Mnesia It can be done as follows: 

    get_employees_by_name(NameList) -> 
  MatchHead = #employee{name = '$1', _ = '_'},
  Result = '$_'
  MatchSpec = [ { MatchHead, [{'=:=', '$1', Name}], [Result]} || Name <- NameList ],
  F = fun() -> 
     mnesia:select(employee, MatchSpec)
  end,
  {atomic, Result} = mnesia:transaction(F),
  Result.