如何在mysql中获取最大字段的对应ID

Question

I am still new to mysql commands and I learned how to get the max value of a column and count of a column. My database is named db and my table (named "foo") looks like this:

+----------+-------------+------+-----+---------+-------+
| Field    | Type        | Null | Key | Default | Extra |
+----------+-------------+------+-----+---------+-------+
| id       | varchar(64) | NO   | PRI | NULL    |       |
| expires  | datetime    | YES  | MUL | NULL    |       |
| extra    | text        | YES  |     | NULL    |       |
| valid    | tinyint(1)  | NO   |     | NULL    |       |
| trust_id | varchar(64) | YES  | MUL | NULL    |       |
| user_id  | varchar(64) | YES  | MUL | NULL    |       |
+----------+-------------+------+-----+---------+-------+

Basically, I want to know if there is a way to get the max date of the expires field and then print out the corresponding fields like user_id and id. So far this is the command I currently use to get the max date from expires in the command line

mysql -u root db -e "select max(id) from foo;"

this alone will give me:

+---------------------+
| max(expires)        |
+---------------------+
| 2016-08-05 17:54:44 |
+---------------------+

What I would like to do is get this back:

+---------------------+--------+--------+
| max(expires)        | id     | user_id|
+---------------------+--------+--------+
| 2016-08-05 17:54:44 |cd97eb4 | 2bf2cec|
+---------------------+--------+--------+ 

So then I would have the max expiration date along with the id and user id for that expiration date.

Any insight is greatly appreciated!

Answer 1

If you just want the id and user_id corresponding to that (max) date, then something like this should do

select expires, id, user_id
from foo
where expires in
    (select max(expires) 
     from foo)

Answer 2

Use order by and limit :

select f.*
from foo f
order by f.expires desc
limit 1;

I think this is the simplest way. And with an index on foo(expires) , it should have the best performance as well.