how to get latest entry of a item when item have multiple rows?

Question

i have an table

tbl_exp

 id| exp_id|qnty|     last_update
 1 |   12  |  10|2010-05-18 19:34:29
 2 |   13  |  50|2010-05-19 19:34:29
 3 |   12  |  50|2010-05-19 19:34:29
 4 |   15  |  50|2010-05-18 19:34:29
 5 |   18  |  50|2010-05-20 19:34:29
 6 |   13  |  70|2010-05-20 19:34:29

now i need only latest entry of each exp_id

 id| exp_id|qnty|     last_update
 3 |   12  |  50|2010-05-19 19:34:29
 6 |   13  |  70|2010-05-20 19:34:29
 4 |   15  |  50|2010-05-18 19:34:29
 5 |   18  |  50|2010-05-20 19:34:29

please suggest me the mysql query to retrive above result??

thanks!

Answer 1

http://stackoverflow.com/search?q=max-per-group

Answer 2

This is gone over in detail here: http://stackoverflow.com/questions/1313120/sql-retrieving-the-last-record-in-each-group

I have tested it and it works.