这是否需要联盟?在联合和布尔条件之间进行选择
SELECT vend_id, prod_id, prod_price
FROM products
WHERE prod_price <= 5
UNION
SELECT vend_id, prod_id, prod_price
FROM products
WHERE vend_id IN (1001,1002);
或者这样做,如果你这样做?
SELECT vend_id, prod_id, prod_price
FROM products
WHERE prod_price <= 5
OR vend_id IN (1001,1002);
你不会得到两行,因为'union'过滤掉重复(而不是'union all')。 – Andomar 2010-06-09 09:05:22