将两个 table 的查询与另一个 table 合并

Question

我需要帮助才能加入三个 table。我可以以某种方式加入两个 tables table1 和 table2 以获得所需的输出，但我想加入另一个 table 以获得一些新的相关专栏。这是我的查询：

select 
[from_bus] as [Node], 
[from_bus_id]  as [Node_id]
from table1 
union 
select 
[to_bus] as [Node], 
[to_bus_id]  as [Node_id]
from table1
union
select 
[from_bus] as [Node], 
[from_bus_id]  as [Node_id]
from table2
union 
select 
[to_bus] as [Node], 
[to_bus_id]  as [Node_id]
from table2

table1 和 table2 的查询输出：

Node Node_ID
A_22  1
A_11  2
B_33  3
C_25  4

节点和Node_ID是唯一的。现在，我有另一个 table3，我需要另一个列 (Zone_ref)，其中包含相应 Zone.

的 IDs

    table3: 
    Zone   Node_Name  Zone_ref
    A      A_22        1
    A      A_11        1
    B      B_33        3 
    B      B_44        3     
    C      C_31        4
    C      C_25        4

我想要这样的东西：

Node Node_ID Zone_ref
A_22  1       1
A_11  2       1
B_33  3       3
C_25  4       4

我可以在一些公共字段中加入 table，但不知道如何将来自两个 table 的一个查询与第三个 table 集成。需要你的建议。顺便说一句，我正在使用访问数据库。谢谢。

Answer 1

尝试使用 Join 进行嵌套子查询。如下所示：

select a.Node, a.Node_id, b.Zone_ref from (
 select 
 [from_bus] as [Node], 
 [from_bus_id]  as [Node_id]
 from table1 
 union 
 select 
 [to_bus] as [Node], 
 [to_bus_id]  as [Node_id]
 from table1
 union
 select 
 [from_bus] as [Node], 
 [from_bus_id]  as [Node_id]
 from table2
 union 
 select 
 [to_bus] as [Node], 
 [to_bus_id]  as [Node_id]
 from table2 ) a
INNER JOIN table3 b ON a.Node = b.Node_Name

将两个 table 的查询与另一个 table 合并

Join a query of two tables with another table

database

ms-access

ms-access-2010