Question

我有两张桌子：

表a：

DOCKER_HOST

表b：

PersonID | name | age | gender  
-------- | ---- | --- | ------  
20       | John | 45  | Male  
30       | Ann  | 50  | Female

我需要从表格＆＃39; a＆＃39;中获取所有值。每个对应的Column1都有一个.PersonID = b.PersonID和MAX ValueID。

此示例中的预期结果如下：

ValueID | PersonID | Column1   
------- | -------- | -------  
1       | 20       | 654321  
2       | 20       | 345653  
3       | 30       | 756756  
4       | 30       | 142857

我试过这个并且不起作用。

 PersonID | name | age | gender | Column1
 -------- | ---- | --- | ------   -------
 20       | John | 45  | Male   | 345653  
 30       | Ann  | 50  | Female | 142857

我猜WHERE子句SELECT ps.*, (SELECT Column1 FROM b ef JOIN (SELECT MAX(ValueID) AS id FROM b WHERE PersonID = ps.PersonID) max ON ef.PersonID = max.id ) AS Column1 FROM a ps中的ps.PersonID无法识别。

我非常感谢你的帮助。

Answer 1

试试这个..大概是valueid是唯一的/身份种子

SELECT ps.*, 
(SELECT Column1 FROM b 
where b.valueId =(SELECT MAX(ValueID) FROM b as x
  WHERE x.PersonID = ps.PersonID)
) AS Column1  
FROM a ps

Answer 2

试试这个：

SELECT ps.*, 
  (SELECT Column1 
   FROM b ef  
   JOIN (SELECT MAX(ValueID) AS id FROM b  
   WHERE PersonID = ps.PersonID) max ON ef.PersonID = max.id ) AS Column1  
FROM a ps

在JOIN中选择MAX值，在另一个SELECT中选择JOIN

2 个答案: