PLSQL Language Referenc-PL/SQL集合和記錄-集合變數賦值-將集合操作結果賦給巢狀表

DECLARE                                            

    TYPE nested_typ IS TABLE OF NUMBER; --定義巢狀表型別

    nt1 nested_typ := nested_typ(1,2,3); nt2 nested_typ := nested_typ(3,2,1);

    nt3 nested_typ := nested_typ(2,3,1,3); nt4 nested_typ := nested_typ(1,2,4);

    answer nested_typ;

    PROCEDURE print_nested_table (nt nested_typ) IS output VARCHAR2(128);

    BEGIN

        IF nt IS NULL THEN DBMS_OUTPUT.PUT_LINE('結果: null 集合');

        ELSIF nt.COUNT = 0 THEN DBMS_OUTPUT.PUT_LINE('結果: empty 集合');

        ELSE

            FOR i IN nt.FIRST .. nt.LAST LOOP

                output := output || nt(i) || ' ';

            END LOOP;

            DBMS_OUTPUT.PUT_LINE('結果: ' || output);

        END IF;

     END print_nested_table;

BEGIN

    answer := nt1 MULTISET UNION nt4;

    print_nested_table(answer);

    answer := nt1 MULTISET UNION nt3;

    print_nested_table(answer);

    answer := nt1 MULTISET UNION DISTINCT nt3;

    print_nested_table(answer);   

    answer := nt2 MULTISET INTERSECT nt3;

    print_nested_table(answer);

    answer := nt2 MULTISET INTERSECT DISTINCT nt3;

    print_nested_table(answer);   

    answer := SET(nt3);

    print_nested_table(answer);

    answer := nt3 MULTISET EXCEPT nt2;

    print_nested_table(answer);

    answer := nt3 MULTISET EXCEPT DISTINCT nt2;

    print_nested_table(answer);

END;