Question

所以我有这两个表：

对象（idObjects，obj_name）关系（idRelations，rel_name，dom_idObjects，cdom_idObjects）

dom和cdom是对象表的FK。它们代表现有对象的关系。

我正在尝试编写一个返回特定depht中的每个关系的查询，以及相应的对象名称。因此，例如，如果我希望depht为1（2个对象之间的简单关系）中的每个关系，我设法让它工作：

SELECT A.rel_name
    ,C1.obj_name AS object1_name
    ,C2.obj_name AS object2_name
FROM relations AS A
INNER JOIN Objects AS C1 ON A.dom_idObjects = C1.idObjects
INNER JOIN Objects AS C2 ON A.cdom_idObjects = C2.idObjects

然而，当试图将其扩展到2或更高的depht时，我没有得到任何结果（并且根据我的DB应该有几个）：

SELECT A.rel_name
    ,C1.obj_name AS object1_name
    ,C2.obj_name AS object2_name
    ,C3.obj_name AS object3_name
    ,C4.obj_name AS object4_name
FROM relations AS A
INNER JOIN Objects AS C1 ON A.dom_idObjects = C1.idObjects
INNER JOIN Objects AS C2 ON A.cdom_idObjects = C2.idObjects
INNER JOIN Objects AS C3 ON A.dom_idObjects = C2.idObjects
    AND A.cdom_idObjects = C3.idObjects
INNER JOIN Objects AS C4 ON A.dom_idObjects = C3.idObjects
    AND A.cdom_idObjects = C4.idObjects

我想我错过了什么。是什么给了什么？

同一个表中有多个INNER JOIN

0 个答案: