Microsoft Access是空问题

Question

我有下面的SQL查询，我很确定我正在接近它。我想要返回的每个元素都没有属性type.Property，其值为“King”

SELECT DISTINCT o.Object_ID, o.ea_guid as CLASSGUID, o.Object_Type as CLASSTYPE, o.name as Name, type.value as RoomType
FROM ((t_object as o
       INNER JOIN t_objectproperties as location
         ON o.Object_ID = location.Object_ID)
         INNER JOIN t_objectproperties as type 
         ON o.Object_ID = type.Object_ID)
WHERE location.Property = 'Location' 
  AND location.Value = 'Queens'
  AND type.Property = 'King' IS NULL

Answer 1

type.Property = 'King'将始终为true或false，永远不为null，

所以

AND type.Property <> 'King'

可能就是你想要的。