| 集合运算 / 联合 | |
图: 查询
SELECT FIRST 5 DISTINCT stock_num, manu_code
FROM stock
WHERE unit_price < 55.00
UNION
SELECT stock_num, manu_code
FROM items
WHERE quantity > 3;
图: 查询结果
stock_num manu_code
5 NRG
5 ANZ
6 SMT
6 ANZ
9 ANZ