mysql-otp/README.md

MySQL/OTP

MySQL/OTP is a client library for connecting to MySQL databases from Erlang/OTP applications. It is a native implementation of the MySQL protocol in Erlang.

Features:

• Works with MySQL 4.1 and later.
• Mnesia style transactions.
• Uses the binary protocol for prepared statements.
• Each connection is a gen_server, which makes it compatible with Poolboy (for connection pooling) and ordinary OTP supervisors.
• No records in the public API.

See also:

• API documenation (Edoc)
• Test coverage (EUnit)
• Why another MySQL driver? in the wiki

This is a work in progress. The API and the value representation may still change. Use a tagged version to make sure nothing breaks.

Synopsis

Opts = [{host, "localhost"}, {user, "foo"}, {password, "hello"},
        {database, "test"}],

%% Connect
{ok, Pid} = mysql:start_link(Opts),

%% Select
{ok, ColumnNames, Rows} = mysql:query(Pid, <<"SELECT * FROM mytable">>),

%% Manipulate data
ok = mysql:query(Pid, "INSERT INTO mytable (foo, bar) VALUES (1, 42)"),

%% Named prepared statements
{ok, foo} = mysql:prepare(Pid, "SELECT * FROM mytable WHERE id=?", foo),
{ok, Columns, Rows} = mysql:execute(Pid, foo, [42]),

%% Unnamed prepared statements
{ok, StmtId} = mysql:prepare(Pid, "SELECT * FROM mytable WHERE id=?"),
{ok, Columns, Rows} = mysql:execute(Pid, StmtId, [42]).

%% Separate calls to fetch more info about the last query
LastInsertId = mysql:insert_id(Pid),
AffectedRows = mysql:affected_rows(Pid),
WarningCount = mysql:warning_count(Pid),

%% An "anonymous prepared statement" with parameters, prepared and executed
%% on the fly. NOT IMPLEMENTED YET.
{ok, ColumnNames, Rows} =
    mysql:query(Pid, <<"SELECT * FROM mytable WHERE id=?">>, [42]),

%% Simple Mnesia style transactions.
%%
%% Note 1: Cannot be nested.
%% Note 2: Not automatically restarted when a deadlock is detected.
%%
%% There are plans to implement nested and restartable transactions. (Issue #7)
Result = mysql:transaction(Pid, fun () ->
    ok = mysql:query(Pid, "INSERT INTO mytable (foo) VALUES (1)"),
    throw(foo),
    ok = mysql:query(Pid, "INSERT INTO mytable (foo) VALUES (1)")
end),
case Result of
    {atomic, ResultOfFun} ->
        io:format("Inserted 2 rows.~n");
    {aborted, Reason} ->
        io:format("Inserted 0 rows.~n")
end

Tests

Run the eunit tests with rebar eunit. For the suite mysql_tests you need MySQL running on localhost and give privileges to the otptest user:

grant all privileges on otptest.* to otptest@localhost identified by 'otptest';

Contributing

Pull request and feature requests are welcome. If you're looking for something to do, pick one of the issues and solve it. Remember to include test cases.

License

GNU Lesser General Public License (LGPL) version 3 or any later version. Since the LGPL is a set of additional permissions on top of the GPL, both license texts are included in the files COPYING and COPYING.LESSER respectively.

We hope this license should be permissive enough while remaining copyleft. If you're having issues with this license, please create an issue in the issue tracker!