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Erlang MySQL driver

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This fork is no longer maintained. Active development has moved to:

https://github.com/Eonblast/Emysql

Usage

Start the application

application:start(emysql).

Add a pool

emysql:add_pool(PoolName, PoolSize, Username, Password, Host, Port, Database, Encoding) -> ok | {error, pool_already_exists}
PoolName = atom()
PoolSize = integer()
Username = string()
Password = string()
Host = string()
Port = integer()
Database = string()
Encoding = atom()

emysql:add_pool(mypoolname, 1, "username", "mypassword", "localhost", 3306, "mydatabase", utf8).

Record Types

-record(ok_packet, {seq_num, affected_rows, insert_id, status, warning_count, msg}).
-record(error_packet, {seq_num, code, msg}).
-record(result_packet, {seq_num, field_list, rows, extra}).

Executing SQL statements

emysql:execute(PoolName, Statement) -> result_packet() | ok_packet() | error_packet()
PoolName = atom()
Statement = string() | binary()

emysql:execute(mypoolname, <<"SELECT * from mytable">>).
#result_packet{field_list=[...], rows=[...]}

emysql:execute(mypoolname, <<"UPDATE mytable SET bar = 'baz' WHERE id = 1">>).
#ok_packet{affected_rows=1}

Executing prepared statements

emysql:prepare(StmtName, Statement) -> ok
StmtName = atom()
Statement = binary() | string()

emysql:prepare(my_stmt, <<"SELECT * from mytable WHERE id = ?">>).
ok

emysql:execute(StmtName, Args) -> result_packet() | ok_packet() | error_packet()
StmtName = atom()
Args = [term()]

emysql:execute(my_stmt, [1]).
#result_packet{field_list=[...], rows=[...]}

Converting Row Data To Records

emysql_util:as_record(ResultPacket, RecordName, Fields) -> Result
ResultPacket = result_packet()
RecordName = atom() (the name of the record to generate)
Fields = atom()
Result = [record()]

-module(fetch_example).
-record(foo, {bar, baz, bat}).

fetch_foo() ->
   Result = emysql:execute(pool1, <<"select bar, baz, bat from foo">>),
   Recs = emysql_util:as_record(Result, foo, record_info(fields, foo)),
   [begin
      io:format("foo: ~p, ~p, ~p~n", [Foo#foo.bar, Foo#foo.baz, Foo#foo.bat])
    end || Foo <- Recs].

TODO:

  • decrementing pool size could close sockets that are in use
  • spawn individual conn_mgr gen_server processes for each pool
  • allow row results to be returned as binary
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