CREATE OR REPLACE FUNCTION person_exists(person_id IN VARCHAR2) RETURN BOOLEAN IS
    l_count PLS_INTEGER;
BEGIN
    SELECT DISTINCT 1 
      INTO l_count 
      FROM people 
     WHERE = person_id;

    RETURN TRUE;
EXCEPTION
    WHEN no_data_found THEN
        RETURN FALSE;
    WHEN too_many_rows THEN
        RETURN TRUE;
END person_exists;

I often need to know if a record exists in a table.  This method is probably the most efficient.  Too many people don't use the exceptions that Oracle provides, which is a shame.

I think I got it from Tom Kyte's site?  Or Steven Feuerstein?

Record Exists function template

table

PL/SQL