Selecting DISTINCT values from an associative array

Problem: Is there any built-in function in Oracle for selecting distinct values from an associative array.

Answer: You can use SET operator but take into account that the set operator doesn't work on nested tables of PL/SQL records. You can use SET on nested tables of single values.

               

Look the following example that shows how to get DISTINCT value form an associative array.

SQL>

DECLARE

    TYPE num_list IS TABLE OF NUMBER;

    id_list       num_list := num_list();

    id_list_2     num_list := num_list();

BEGIN

    FOR i IN (SELECT 1 AS value

                FROM all_tables

               WHERE ROWNUM < 10

             )

    LOOP

        id_list.EXTEND;

        id_list(id_list.LAST) := i.value;

    END LOOP;

    FOR o IN id_list.FIRST .. id_list.LAST

    LOOP

        dbms_output.put_line('Org: '||id_list(o));

    END LOOP; 

    id_list_2 := set( id_list ) ;

    FOR d IN id_list_2.FIRST .. id_list_2.LAST

    LOOP

        dbms_output.put_line('New: '||id_list_2(d));

    END LOOP; 

END;

/

--Output

Org: 1

Org: 1

Org: 1

Org: 1

Org: 1

Org: 1

Org: 1

Org: 1

Org: 1

New: 1