Catching DML exceptions in PL/pgSQL

 Hello all,
 (and sorry if this has been aswered before)

 Take this piece of code for example:
 .....................
begin
     _res.code:=1;
     select id into iid from log where id=_id;
     if not found then begin
         _res.msg:=''insert'';
         insert into log (log, data) values (_log, _data);
         if not found then begin
             _res.msg:=_res.msg || '' error'';
             _res.code:=-1;
         end;
         end if;
     end;
     else begin
.....................
 The thing is if _data (parameter) is null and table has a (data <> null) check, the insert would fail and abort the function before my "if not found" test.

 I'm porting a java app. from mssql to postgresql, and the java code relies on the stored procedure to always return it's status (in _res.code in this case).

 Is there anything I can do to make sure the function always returns _res ?
 Something along the lines of Oracle's exception handling, or the @@error trick in mssql ?


 Regards,
 --
 Radu-Adrian Popescu
 CSA, DBA, Developer
 Aldratech Ltd.