The best way to know if you a data in a table

Question

hello
I have a doubt what 's the best way to know if you have a value in a table .For example I have a table called Vehicle , that have two rows id and name . Well I want to know before do somthing if the vehicle with mane '11111', exist or not .
Nowadays i do this operation with a : select count ( id ) into num from vehicle;
This is the best way ???
THANKS

Answer 1

Hello
Well here's an alternative that may help in your situation. The idea is that you put all of your values that you will be testing for the existence of, in a collection. Then use INTERSECT to find out which of those are already present in the table.
It may well turn out to be completely useless, but I'm trying to avoid working on what I am supposed to be working on, and I thought I'd try it out ;-)
CREATE TABLE dt_test_vehicle(veh_name     VARCHAR2(20));
INSERT INTO dt_test_vehicle values('1111');
INSERT INTO dt_test_vehicle values('2222');
INSERT INTO dt_test_vehicle values('4444');
INSERT INTO dt_test_vehicle values('5555');
INSERT INTO dt_test_vehicle values('6666');
CREATE TYPE dt_tt_varchar2 IS TABLE OF VARCHAR2(20)
set serveroutput on
DECLARE
     ltt_Params     dt_tt_varchar2;
     ltt_Result     dt_tt_varchar2;
BEGIN
     ltt_Params := dt_tt_varchar2();
     ltt_Params.EXTEND(4);
     ltt_Params(1) := '1111';
     ltt_Params(2) := '2222';
     ltt_Params(3) := '3333';
     ltt_Params(4) := '4444';
     SELECT
          veh_name
     BULK COLLECT INTO
          ltt_Result
     FROM
          (SELECT
               veh_name
          FROM
               dt_test_vehicle
          INTERSECT
          SELECT
               column_value
          FROM
               TABLE(CAST(ltt_Params AS dt_tt_varchar2))
     IF ltt_Result.COUNT > 0 THEN
          FOR li_Idx IN ltt_Result.FIRST..ltt_Result.LAST LOOP
               dbms_output.put_line(ltt_Result(li_Idx));
          END LOOP;
     ELSE
          dbms_output.put_line('Nothing there, everything is good to go');
     END IF;
END;Delete rows from the test table to see the changing results. The main reason I was thinking of this way of doing it was so you could handle your messages in one hit rather than having to have a separate exception for each parameter you are testing.
HTH
David
Sorry, I just re-read your post, and you need to know if these parameters are NOT there, in which case you should give an error. In that case, you could change the INTERSECT for MINUS. If you have anything in the resulting collection, these are the parameters that are missing from the table.
Message was edited by:
david_tyler