Question

Table 1   Bus_ID   Owner_ID   #owners in Bus
           12345       5558        3
           12345       5856        3
           52858     **7894**      1
           12345       1254        3

Table 2   Owner_1   Owner_2    Relationship
           5558      5856    Parent of Owner_1
           5558      1254    Parent of Owner_1
           1254      5856    Spouse
           5856      1254    Spouse
           **7894**  6868    Spouse
           6868    **7894**  Spouse

我有两个要互相连接的桌子。只能加入Owner_ID = Owner_1或Owner_ID = Owner_2上。我最终希望获得表1中的Owner_ID。

我的预期结果：

Bus_ID  Owner_ID  Owner_1  Owner_2  Relationship 
 12345    5558     5558     5856   Parent of Owner_1
 12345    5558     5558     1254   Parent of Owner_1
 12345    5856     5856     1254   Spouse
 12345    1254     1254     5856   Spouse

您看到Owner_ID是否未出现在表1中，我不希望它出现在联合表中，但是当加入 7894 时，因为表2中存在关系，它将出现无论如何，我正在加入他们。在连接这两个表时，我需要帮助。

select Bus_ID, Owner_ID, Owner_1, Owner_2, Relationship from table 1 
join table 2 on (Owner_ID = Owner_1 AND Owner_ID = Owner_2).

此查询不会提供我期望的输出。

Answer 1

尝试通过别名将table2的多个实例与连接一起使用

select Bus_ID, Owner_ID, t2.Owner_1, t3.Owner_2, t2.Relationship 
from table1 t1 join table2 t2 on t1.Owner_ID = t2.Owner_1 
join table2 t3 on t1.Owner_ID = t3.Owner_2

Answer 2

您可以尝试以下操作：

select 
    Bus_ID, Owner_ID, Owner_1, Owner_2, Relationship 
from table 1 
inner join table 2 on Owner_ID = Owner_1

UNION

select 
    Bus_ID, Owner_ID, Owner_1, Owner_2, Relationship 
from table 1 
inner join table 2 on Owner_ID = Owner_2

这样您将获得：

所有符合条件Owner_ID = Owner_1的行
所有符合条件Owner_ID = Owner_2的行

，您将一次返回所有这些。

在两个不同的列上联接表

2 个答案: