mysql and zend db table problems with select the max id of each user

mysql and zend db table problems with select the max id of each user

I am having some mysql problems, using zend db table..i want to select the
last entry in a place for each user, i have got a table called checkin,
wich register the user, the place where the user enters, the datatime of
the entry...im using zend framework and zend db table.. so my table
checkins has this info id_checkin |id_utilizador|id_tag|data_leitura
|data_receberescrita
7 |20 |74 |2013-08-27 12:30:00 |2013-08-27 12:35:10
8 |20 |75 |2013-08-27 16:17:00 |2013-08-14 16:18:00
9 |16 |74 |2013-08-27 16:30:00 |2013-08-27 16:35:10
i want to show the date on a jqgrid.. the result that i am trying to
achieve is to appear the info of the id_checkin 8 and 9.