你有兩個表,
table property (id, title, description, status, primary key(id))
table object_property (id, object_id, property_id, value, primary key(id))
其中object_property.property_id是外鍵property.id
您可以加入共享一個公共密鑰這些表來獲取行(元組),
SELECT p.id, p.title, p.description, p.status, op.id, op.object_id, op.value
FROM property AS p LEFT JOIN object_property AS op ON p.id = op.property_id ;
您可以使用INNER JOIN,LEFT JOIN,RIGHT JOIN,這取決於你想匹配的東西,但在這裏,你想找到屬性中id不存在於object_property表(外部部分LEFT OUTER JOIN)中的行,
SELECT p.id, p.title, p.description, p.status
FROM property AS p
WHERE p.id NOT IN (SELECT DISTINCT op.property_id FROM object_property AS op) ;