如何从 mysql 中的 group by 和 groupconcat 其他字段中获取最大值？

Question

I tried to get the max value corresponding row and group_concat all the email address.

MySql table:

id  firstName LastName  email         value
1   John      Seam      sa@gmail.com   450
2   John      Seam      js@yahoo.com    0  
3   Richard   Min       aa@gmail.com    0 

expected output:

id  firstName LastName   email                          value
1   John      Seam      sa@gmail.com|js@yahoo.com       450
3   Richard   Min       aa@gmail.com                     0 

I tried the following query:

select id,firstName,LastName,group_concat(email) ,max(value) 
from table 
group by firstName,LastName

but it gave wrong result:

id  firstName LastName   email                          value
2   John      Seam      sa@gmail.com|js@yahoo.com       450
3   Richard   Min       aa@gmail.com                     0 

instead of id 1 I am getting id 2. If I remove the group_concat it gives the correct output.

Answer 1

If you want the id of the row with the max value then use GROUP_CONCAT() for the ids ordered by value DESC and take the first one of the result with the function SUBSTRING_INDEX() :

SELECT SUBSTRING_INDEX(GROUP_CONCAT(id ORDER BY value DESC), ',', 1) id,
       firstName, LastName,
       GROUP_CONCAT(email SEPARATOR '|') email,
       MAX(value) value
FROM tablename
GROUP BY firstName, LastName

See the demo .
Results:

id	firstName	LastName	mail	value
1	John	Seam	sa@gmail.com|js@yahoo.com	450
3	Richard	Min	aa@gmail.com	0

Answer 2

This answers the original version of the question.

Your query is malformed -- the select is inconsistent with the group by . I would suggest a very different approach:

select t.*,
       (select group_concat(t2.email)
        from table t2
       ) as emails
from table t
order by value desc
limit 1;

select id,firstName,LastName,group_concat(email),max(value) from table group by firstName,LastName

Answer 3

You can use something like this, if you have more than one row with 450, you will need to add also a rownumber to it

CREATE TABLE Table1 (`id` int, `firstName` varchar(7), `LastName` varchar(4), `email` varchar(12), `value` int); INSERT INTO Table1 (`id`, `firstName`, `LastName`, `email`, `value`) VALUES (1, 'John', 'Seam', 'sa@gmail.com', 450), (2, 'John', 'Seam', 'js@yahoo.com', 0), (3, 'Richard', 'Min', 'aa@gmail.com', 0);

 SELECT t1.`id`, t1.`firstName`, t1.`LastName`,mailG,max_value FROM Table1 t1 INNER JOIN (SELECT `firstName`, `LastName`,GROUP_CONCAT(`email` SEPARATOR ' | ') mailG, MAX(`value`) max_value FROM Table1 GROUP BY `firstName`, `LastName`) t2 ON t1.`firstName` = t2.`firstName` AND t1.`LastName` = t2.`LastName` AND t1.`value` = t2.max_value

 id | firstName | LastName | mailG | max_value -: |:-------- |:------- |:-------------------------- | --------: 1 |  John | Seam | sa@gmail.com |  js@yahoo.com |  450 3 |  Richard | Min | aa@gmail.com |  0 

db<>fiddle here