There is an mnesia example at the following url:
http://www.erlang.org/doc/apps/mnesia/Mnesia_chap2.html#id64245
However, the example code is incomplete.
So I added copied some of the Erlang examples functions and created some new functions to use on the DB.
Some of the functions from the page below do not seem to work (all_*).
%-----------------------------------------------------------------
% compile in the shell with
% > c(company).
%-----------------------------------------------------------------
http://www.erlang.org/doc/apps/mnesia/Mnesia_chap2.html#id64245
However, the example code is incomplete.
So I added copied some of the Erlang examples functions and created some new functions to use on the DB.
Some of the functions from the page below do not seem to work (all_*).
%-----------------------------------------------------------------
%company.erl% compile in the shell with
% > c(company).
%-----------------------------------------------------------------
-module(company).
-export([
init/0,
insert_emp/3,
mk_projs/2,
mk_project/2,
raise/2,
all_females/0,
all_males/0,
raise_females/1,
over_write/2,
read_employee/1,
read_employee_table/2,
read_emp1/2
]).
-include_lib("stdlib/include/qlc.hrl").
-include("company.hrl").
%%----------------------------------------
init() ->
mnesia:create_table(employee,
[{attributes, record_info(fields, employee)}]),
mnesia:create_table(dept,
[{attributes, record_info(fields, dept)}]),
mnesia:create_table(project,
[{attributes, record_info(fields, project)}]),
mnesia:create_table(manager, [{type, bag},
{attributes, record_info(fields, manager)}]),
mnesia:create_table(at_dep,
[{attributes, record_info(fields, at_dep)}]),
mnesia:create_table(in_proj, [{type, bag},
{attributes, record_info(fields, in_proj)}]).
%%----------------------------------------
insert_emp(Emp, DeptId, ProjNames) ->
Ename = Emp#employee.name,
Fun = fun() ->
mnesia:write(Emp),
AtDep = #at_dep{emp = Ename, dept_id = DeptId},
mnesia:write(AtDep),
mk_projs(Ename, ProjNames)
end,
mnesia:transaction(Fun).
%%----------------------------------------
mk_projs(Ename, [ProjName|Tail]) ->
mnesia:write(#in_proj{emp = Ename, proj_name = ProjName}),
mk_projs(Ename, Tail);
mk_projs(_, []) -> ok.
%%----------------------------------------
mk_project(ProjName, ProjNumber) ->
mnesia:write(#project{name = ProjName, number = ProjNumber}).
%%----------------------------------------
raise(Eno, Raise) ->
F = fun() ->
[E] = mnesia:read(employee, Eno, write),
Salary = E#employee.salary + Raise,
New = E#employee{salary = Salary},
mnesia:write(New)
end,
mnesia:transaction(F).
%%----------------------------------------
all_males() ->
F = fun() ->
Male = #employee{sex = male, name = '$1', _ = '_'},
mnesia:select(employee, [{Male, [], ['$1']}])
end,
mnesia:transaction(F).
%%----------------------------------------
all_females() ->
F = fun() ->
Female = #employee{sex = female, name = '$1', _ = '_'},
mnesia:select(employee, [{Female, [], ['$1']}])
end,
mnesia:transaction(F).
%%----------------------------------------
raise_females(Amount) ->
F = fun() ->
Q = qlc:q([E || E <- mnesia:table(employee),
E#employee.sex == female]),
Fs = qlc:e(Q),
over_write(Fs, Amount)
end,
mnesia:transaction(F).
%%----------------------------------------
over_write([E|Tail], Amount) ->
Salary = E#employee.salary + Amount,
New = E#employee{salary = Salary},
mnesia:write(New),
1 + over_write(Tail, Amount);
over_write([], _) -> 0.
%%----------------------------------------
read_employee(Eno) ->
Fun = fun() ->
mnesia:read({employee,Eno})
end,
{atomic,[Row]}=mnesia:transaction(Fun),
io:format("~p~n",[Row#employee.name]).
%%----------------------------------------
read_employee_table(Table,Eno) ->
mnesia:read({Table,Eno})
.
%read_employee_name(Eno, Table, Field) ->
% {atomic,[Row]}=mnesia:transaction(read_employee_table(Table, Eno)),
% io:format("~p~n",[RowTable.Field]).
%
read_emp1(Eno, Field) ->
Fun = fun() ->
mnesia:read({employee,Eno})
end,
{atomic,[Row]}=mnesia:transaction(Fun),
io:format("~p~n",[Row#employee.Field]).
% io:format("~p~n",[Row#employee.emp_no]).
% mnesia:read(employee, Eno, write).
%%----------------------------------------
%Fun = fun() ->
% mnesia:read({employee,115018})
% end,
% {atomic,[Row]}=mnesia:transaction(Fun),
% io:format("~p~n",[Row#employee.emp_no]).
%-----------------------------------------------------------------
%company.hrl% compile in the shell with
% > rr("company").
%-----------------------------------------------------------------
-record(employee, {emp_no,
name,
salary,
sex,
phone,
room_no}).
-record(dept, {id,
name}).
-record(project, {name,
number}).
-record(manager, {emp,
dept}).
-record(at_dep, {emp,
dept_id}).
-record(in_proj, {emp,
proj_name}).
%-----------------------------------------------------------------
% company_sample.erl% compile in the shell with
% > c(company_sample).
%-----------------------------------------------------------------
erl -mnesia dir '"/tmp/Mnesia.Company"'
mnesia:create_schema([node()]).
mnesia:start().
c(company.erl).
rr("company.hrl").
company:init().
mnesia:info().
%Employees
Emp0 = #employee{emp_no = 104465, name = "Johnson Torbjorn", salary = 1, sex = male, phone = 99184, room_no = {242,038}}, company:insert_emp(Emp0, 'B/SFR', [otp]).
Emp1 = #employee{emp_no = 107912, name = "Carlsson Tuula", salary = 2, sex = female, phone = 94556, room_no = {242,056}}, company:insert_emp(Emp1, 'B/SFR', [otp]).
Emp2 = #employee{emp_no = 114872, name = "Dacker Bjarne", salary = 3, sex = male, phone = 99415, room_no = {221,035}}, company:insert_emp(Emp2, 'B/SFR', [otp]).
Emp3 = #employee{emp_no = 104531, name = "Nilsson Hans", salary = 3, sex = male, phone = 99495, room_no = {222,026}}, company:insert_emp(Emp3, 'B/SFR', [otp]).
Emp4 = #employee{emp_no = 104659, name = "Tornkvist Torbjorn",salary = 2, sex = male, phone = 99514, room_no = {222,022}}, company:insert_emp(Emp4, 'B/SFR', [otp]).
Emp5 = #employee{emp_no = 104732, name = "Wikstrom Claes", salary = 2, sex = male, phone = 99586, room_no = {221,015}}, company:insert_emp(Emp5, 'B/SFR', [otp]).
Emp6 = #employee{emp_no = 117716, name = "Fedoriw Anna", salary = 1, sex = female, phone = 99143, room_no = {221,031}}, company:insert_emp(Emp6, 'B/SFR', [otp]).
Emp7 = #employee{emp_no = 115018, name = "Mattsson Hakan", salary = 3, sex = male, phone = 99251, room_no = {203,348}}, company:insert_emp(Emp7, 'B/SFR', [otp]).
%company:all_females();
%company:all_males();
% %Dept
%
% {dept, 'B/SF', "Open Telecom Platform"}.
% {dept, 'B/SFP', "OTP - Product Development"}.
% {dept, 'B/SFR', "Computer Science Laboratory"}.
%
%
% %Projects
%company:mk_project(erlang , 1).
%company:mk_project(otp , 2).
%company:mk_project(beam , 3).
%company:mk_project(mnesia , 5).
%company:mk_project(wolf , 6).
%company:mk_project(documentation, 7).
%company:mk_project(www , 8).
%
%
% % The above three tables, titled employees, dept, and projects, are the tables which are made up of real records.
% % The following database content is stored in the tables which is built on relationships.
% % These tables are titled manager, at_dep, and in_proj.
%
% %Manager
%
% {manager, 104465, 'B/SF'}.
% {manager, 104465, 'B/SFP'}.
% {manager, 114872, 'B/SFR'}.
%
%
% %At_dep
%
% {at_dep, 104465, 'B/SF'}.
% {at_dep, 107912, 'B/SF'}.
% {at_dep, 114872, 'B/SFR'}.
% {at_dep, 104531, 'B/SFR'}.
% {at_dep, 104659, 'B/SFR'}.
% {at_dep, 104732, 'B/SFR'}.
% {at_dep, 117716, 'B/SFP'}.
% {at_dep, 115018, 'B/SFP'}.
%
%
% %In_proj
%
% {in_proj, 104465, otp}.
% {in_proj, 107912, otp}.
% {in_proj, 114872, otp}.
% {in_proj, 104531, otp}.
% {in_proj, 104531, mnesia}.
% {in_proj, 104545, wolf}.
% {in_proj, 104659, otp}.
% {in_proj, 104659, wolf}.
% {in_proj, 104732, otp}.
% {in_proj, 104732, mnesia}.
% {in_proj, 104732, erlang}.
% {in_proj, 117716, otp}.
% {in_proj, 117716, documentation}.
% {in_proj, 115018, otp}.
% {in_proj, 115018, mnesia}.
%
% otp = "otp".
% Emp = #employee{emp_no= 104732,
% name = klacke,
% salary = 7,
% sex = male,
% phone = 98108,
% room_no = {221, 015}},
% insert_emp(Me, 'B/SFR', [otp]).
