以一对多关系连接两个 sql table，但想要第二个 table 的最大值

Question

我正在尝试加入两个 tables，其中一个是独特的功能，秒是在与独特功能相关的几个日期进行的读数。我想要第一个 table 中的所有记录加上最近的阅读。在添加形状字段之前，我能够得到我正在寻找的结果。通过使用代码

SELECT
   Table1.Name, Table1.ID, Table1.Shape, 
   Max(Table2.DATE) as Date 
FROM         
   Table1 
LEFT OUTER JOIN
   Table2 ON Table1.ID = table2.ID
GROUP BY
   Table1.Name, Table1.ID, Table1.Shape

形状字段是几何类型，我收到错误

'The type "Geometry" is not comparable. It can not be use in the Group By Clause'

所以我需要换一种方式，但不确定如何。

下面是两个 table 的示例和所需的结果。

Table1
Name| ID |Shape
AA1 | 1  | X
BA2 | 2  | Y
CA1 | 3  | Z
CA2 | 4  | Q

Table2
ID | Date
1  | 5/27/2013
1  | 6/27/2014
2  | 5/27/2013
2  | 6/27/2014
3  | 5/27/2013
3  | 6/27/2014

我想要的结果是

Name| ID |Shape |Date
AA1 | 1  | X    | 6/27/2014
BA2 | 2  | Y    | 6/27/2014
CA1 | 3  | Z    | 6/27/2014
CA2 | 4  | Q    | Null

Answer 1

尝试将几何体转换为 varchar。

Select Table1.Name, Table1.ID, cast(Table1.Shape as varchar(1)) AS Shape, Max(Table2.DATE) as Date 

FROM         Table1 LEFT OUTER JOIN
                      Table2 ON Table1.ID = table2.ID

Group By Table1.Name, Table1.ID,  cast(Table1.Shape as varchar(1))

Answer 2

您可以在 CTE 中对 Table2 进行聚合，找到每个 ID 的 MAX(DATE)，然后将该结果加入 Table1:

WITH AggregatedTable2(ID, MaxDate) AS
(
    SELECT 
        ID, MAX(DATE) 
    FROM 
        Table2 
    GROUP BY 
        ID
)
SELECT
    t1.ID, t1.Name, t1.Shape, t2.MaxDate
FROM
    Table1 t1
LEFT JOIN
    AggregatedTable2 t2 ON t1.ID = t2.ID

Answer 3

试试这个：

SELECT  t1.Name
        , t1.ID
        , t1.Shape
        , MAX(t2.Date) As Date
FROM    Table1 AS t1
LEFT JOIN Table2 AS t2
        ON  t2.ID = t1.ID
GROUP
    BY  t1.Name
        , t1.ID
        , t1.Shape

以一对多关系连接两个 sql table，但想要第二个 table 的最大值

Joining two sql tables with a one to many relationship, but want the max of the second table

sql

sql-server

max

outer-join