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Message |
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| phicarre |
 Posted: Tue Jun 16, 2009 2:46 pm |
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User
Joined: 23 Mar 2009
Posts: 14
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Hello,
I try to interface a mySQL database with ODBC by using a gen_server module.
When I call sql_query, I jump in the terminate callback with the following message (I simplified):
function_clause, [{odbc,sql_query,[<0,223,0>,<<"hello">>,infinity]] ...
in Init, I do:
Code:
process_flag(trap_exit,true),
odbc:start(),
ConnectString = "Driver={MySQL ODBC 5.1 Driver};Server=localhost;Database=myDB; User=root;Password=myPwd;Option=3;",
{ok,Ref}= odbc:connect(ConnectString, [{scrollable_cursors,off}]),
{ok, [Ref]},
in handle_cast, I do:
Code:
handle_cast(Msg,Ref)->
Result = sql_query(Ref,Msg), ***** hangs here *****
{noreply,Ref}.
in terminate, I do
Code:
terminate(Reason,Ref)->
odbc:disconnect(Conn),
odbc:stop(),
io:format("Reason: ~s~n",[Reason]),
ok.
I have a method:
Code:
sql_query(Msg)->
gen_server:cast(?MODULE,Msg).
I was expected an error such "wrong SQL syntax" !
Any idea ? I think the error is in my gen_server but I don't see it ...
I tried with a string syntaxically correct but I had the same message. |
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| Cy6erBr4in |
| Posted: Tue Jun 16, 2009 6:52 pm |
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Joined: 16 Oct 2008
Posts: 9
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Hej!
It would be better to see full version of your code.
I don`t see a call of the odbc:sql_query function in the showed code at all.
Code:
function_clause, [{odbc,sql_query,[<0,223,0>,<<"hello">>,infinity]]
this error means that you tried to call function which can`t match arguments you passed.
for example:
Code:
some_fun({test, Data}, Arg2) ->
<some code here>.
another_fun() ->
some_fun({test1, "Test"}, true).
if you try this code, you will get an error with the same reason ("function_clause").
Good luck! |
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| phicarre |
| Posted: Tue Jun 16, 2009 9:52 pm |
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User
Joined: 23 Mar 2009
Posts: 14
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I didn't copy correctly the code ...
Result = odbc:sql_query(Ref,Msg), ***** hangs here *****
sql_query(Ref,SQLquery)-> ResultTuple | [ResultTuple] | {error,Reason} according to the doc. |
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| phicarre |
| Posted: Tue Jun 16, 2009 10:07 pm |
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User
Joined: 23 Mar 2009
Posts: 14
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Here is the full code:
Code:
-module(database).
-behaviour(gen_server).
%% External exports
-export([start_link/1]).
-export([mysql_query/1]).
%% gen_server callbacks
-export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2, code_change/3]).
%% ====================================================================
%% Method
%% ====================================================================
mysql_query(Querystring)->
gen_server:cast(?MODULE,Querystring).
%% ====================================================================
%% Server functions
%% ====================================================================
start_link(Name)->
io:format("--> Démarrage du serveur Database ~s~n",[Name]),
gen_server:start_link({local,?MODULE},?MODULE,[],[]).
%% --------------------------------------------------------------------
%% Function: init/1
%% Description: Initiates the server
%% Returns: {ok, State} |
%% {ok, State, Timeout} |
%% ignore |
%% {stop, Reason}
%% --------------------------------------------------------------------
init([]) ->
process_flag(trap_exit,true),
case odbc:start() of
X when X =:= ok;X =:= {error,{already_started,odbc}} ->
ConnectString = "Driver={MySQL ODBC 5.1 Driver};Server=localhost;Database=myDB; User=root;Password=myPwd;Option=3;",
case odbc:connect(ConnectString, [{scrollable_cursors,off}]) of
{ok,Conn} ->
io:format("ODBC Starting on Pid ~p~n",[Conn]),
{ok, Conn};
{error,Reason} ->
io:format("ODBC Connection error; ~s~n",[Reason]),
{ok,odbc_error} % ???
end;
Other ->
io:format("ODBC Connection error; ~s~n",[Other]),
{stop,odbc_not_started} % ???
end.
%% --------------------------------------------------------------------
%% Function: handle_call/3
%% Description: Handling call messages
%% Returns: {reply, Reply, State} |
%% {reply, Reply, State, Timeout} |
%% {noreply, State} |
%% {noreply, State, Timeout} |
%% {stop, Reason, Reply, State} | (terminate/2 is called)
%% {stop, Reason, State} (terminate/2 is called)
%% --------------------------------------------------------------------
handle_call(Request, From, State) ->
Reply = ok,
{reply, Reply, State}.
%% --------------------------------------------------------------------
%% Function: handle_cast/2
%% Description: Handling cast messages
%% Returns: {noreply, State} |
%% {noreply, State, Timeout} |
%% {stop, Reason, State} (terminate/2 is called)
%% --------------------------------------------------------------------
handle_cast(Msg, Conn) ->
io:format("cast on Pid ~p~n",[Conn]),
Qres = odbc:sql_query(Conn,Msg),
{noreply, State}.
%% --------------------------------------------------------------------
%% Function: handle_info/2
%% Description: Handling all non call/cast messages
%% Returns: {noreply, State} |
%% {noreply, State, Timeout} |
%% {stop, Reason, State} (terminate/2 is called)
%% --------------------------------------------------------------------
handle_info(Info, Conn) ->
{noreply, Conn}.
%% --------------------------------------------------------------------
%% Function: terminate/2
%% Description: Shutdown the server
%% Returns: any (ignored by gen_server)
%% --------------------------------------------------------------------
terminate(Reason, Conn) ->
odbc:disconnect(Conn),
odbc:stop(),
io:format("Terminated: reason = ~s~n",[Reason]),
ok.
%% --------------------------------------------------------------------
%% Func: code_change/3
%% Purpose: Convert process state when code is changed
%% Returns: {ok, NewState}
%% --------------------------------------------------------------------
code_change(OldVsn, State, Extra) ->
{ok, State}.
%% --------------------------------------------------------------------
%%% Internal functions
%% --------------------------------------------------------------------
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| phicarre |
| Posted: Wed Jun 17, 2009 1:25 pm |
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User
Joined: 23 Mar 2009
Posts: 14
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Forget my question, I found myself
The correct syntax is
Result=odbc:sql_query(Ref,[Msg])
The documentation is wrong ... |
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| Cy6erBr4in |
| Posted: Wed Jun 17, 2009 4:51 pm |
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Joined: 16 Oct 2008
Posts: 9
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Good work! 
So, I suppose it`s good reason to send a "patch" for the documentation!
/Regards,
Alexander |
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| wuji |
| Posted: Sat Sep 15, 2012 7:06 am |
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| mbtshoes88 |
| Posted: Wed Sep 19, 2012 8:50 am |
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