A 테이블
==================================
03-01  홍길동 연필 5,000
03-01  홍길동 공책 1,000
03-01  홍길동 볼펜 4,000
03-02  박지성 연필 5,000
==================================

B 테이블
==================================
03-01 홍길동 현금 10,000
03-02 박지성 카드  5,000
==================================

위 두 테이블을
====================================
03-01 홍길동 연필 5,000 현금 10,000
03-01 홍길동 공책 1,000
03-01 홍길동 볼펜 4,000
03-02 박지성 연필 5,000 카드 5,000
====================================
이렇게만들고 싶습니다. 도와 주세요..


select distinct
      date,
      name,
      product,
      cashcard,
      mast,
      money
from(
select a_date as date,
      a_name as name,
      a_product as product
      null is cashcard,
      a_money as mast,
      0 as money
from a_table
union
select b_date as date,
      null is name,
      null is product,
      b_cashcard as cashcard,
      0 as mast,
      b_money as money)
group by date,
      name,
      product,
      cashcard
이런식으로 했는데 null값이 group by가 안되더라구요..