Oracle: Is there a way to get recent SQL syntax errors?

Question

We are seeing a lot of "ORA-00936: missing expression" errors in our application log. Is there a way in Oracle to determine what statement(s) are failing?

I tried querying v$sql, but these statements are not inserted into that view, since they don't pass the syntax checks.

Our C# application is using Linq to generate a query to an Oracle database. This makes it a bit difficult to get the sql query from the application. I was hoping I could just get it from Oracle easier.

Answer 1

You can create a trigger in Oracle that will log all errors (or pretty much all - NO_DATA_FOUND is not considered an error). In the example below, any error in the schema is recorded in the TRACK_DETAIL table (error in one row, failed SQL in the next). You can make it more sophisticated with a sequence number, date/time etc.

create table track_detail (val varchar2(4000));

create or replace procedure track (p_text IN VARCHAR2) IS
  PRAGMA AUTONOMOUS_TRANSACTION;
begin
  insert into track_detail(val)
  values (p_text);
  commit;
end;
.
/
create or replace TRIGGER log_err after servererror on schema
DECLARE
  v_temp VARCHAR2(2000) := substr(dbms_utility.format_error_stack,1,2000);
  v_num NUMBER;
  v_sql_text ora_name_list_t;
begin
  v_temp := translate(v_temp,'''','"');
  track(v_temp);
  v_num  := ora_sql_txt(v_sql_text);
  v_temp := null;
  BEGIN
    FOR i IN 1..v_num LOOP
      v_temp := v_temp || v_sql_text(i);
    END LOOP;
  EXCEPTION
    WHEN VALUE_ERROR THEN NULL;
  END;
  v_temp := translate(v_temp,''''||chr(0)||chr(10),'"');
  track(v_temp);
end;
/

Remember to drop (or disable) the trigger when you have finished with it.

Answer 2

If you can enable sql tracing from the application code somehow (alter session set sql_trace=true), the statements will show up in the trace files on the database host.

Answer 3

Try SQL monitoring solution from Kris Vandermotten blog.

Also you can redirect log with DataContext.Log property :

using (NorthwindDataContext context = new NorthwindDataContext())
{
  context.Log = Console.Out;
}

Or use any other debugging tools like LInQ to Entities Visualizer ...

Answer 4

You could try using something like Wireshark on the port used to connect to Oracle to see what SQL statements are being sent. Might not be the best answer--but it might get you where you need to go quicker.