Question

I have a table like this:

key data created
1   a    14:15
2   b    14:16
2   c    14:17
1   a    14:18
3   b    14:19
3   c    14:20
3   a    14:21
1   b    14:22
2   c    14:23
2   c    14:24

I want to get the last 2 unique keys with the latest data inserted. in other word, i want a query that will get me: 1,2

but when I do something like this:

SELECT distinct(key) FROM logs ORDER BY created DESC LIMIT 0,1

or this:

SELECT key FROM logs GROUP BY key ORDER BY created DESC LIMIT 0,1

I only get: 2,3
probably because these are the last keys in the table.
I couldn’t figure out how to get the 2 keys with the latest data

Answer 1

Try this:

SELECT `key`, MAX( `created` ) AS `maxcreated`
FROM `logs`
GROUP BY `key`
ORDER BY `maxcreated` DESC 
LIMIT 0,2

You did not select the maximum (that is the the latest creation time) per key.

So just use GROUP BY to select per key and add a MAX( created ) to select the last appearance for each key. Applying the respective ORDER BY and LIMIT clauses, you get the desired result.

Example Fiddle