选择mysql中没有自动增量的最后一行

Question

I'm trying to make a temp logging database. Still on the learnig level.

How do I get the last row from the database?

select * from tempdat order by tdate desc limit 1 

gives the first entry of the day but I want the last. See below, it could return the entry whit time 21:25:03

+------------+----------+------+-------------+
| 2014-03-29 | 21:20:02 | inne |      22.875 |
| 2014-03-29 | 21:25:03 | inne |      22.875 |
+------------+----------+------+-------------+
1933 rows in set (0.16 sec)

mysql> select * from tempdat order by tdate desc limit 1;

+------------+----------+------+-------------+
| tdate      | ttime    | zone | temperature |
+------------+----------+------+-------------+
| 2014-03-29 | 00:00:03 | inne |      21.250 |
+------------+----------+------+-------------+
1 row in set (0.03 sec)

Answer 1

Just use two criteria for ordering: first tdate , then ttime . For example:

    SELECT * 
      FROM tempdat 
  ORDER BY tdate DESC, ttime DESC 
     LIMIT 1;

Note that order direction should be specified after each column used. ORDER BY tdate, ttime DESC will first order all the records by tdate ASC .