Catching unnamed Oracle errors

Question

How do you handle specific Oracle errors such as the following:
declare
  dummy varchar2(100);
begin
  select distinct y into dummy
  from
    (select 'x' x, 'y' y
     from dual
     union all
     select 'x' x, 'y' y
     from dual)
  order by x;
  exception when ???
end;What would go in the ??? part if I wanted to specifically handle the ORA-01791 error.
Message was edited by:
SamB

Answer 1

something like this...
SQL> DECLARE
  2   dummy VARCHAR2(100);
  3   v_error EXCEPTION;
  4  
  5   PRAGMA EXCEPTION_INIT(v_error, -01791);
  6  BEGIN
  7   SELECT DISTINCT y
  8   INTO dummy
  9   FROM (SELECT 'x' x, 'y' y FROM dual
10         UNION ALL
11      SELECT 'x' x, 'y' y FROM dual)
12   ORDER BY x;
13  EXCEPTION
14   WHEN v_error THEN
15     DBMS_OUTPUT.PUT_LINE('Exception Raised.');
16  END;
17  /
Exception Raised.
PL/SQL procedure successfully completed.