php - MySQL selecting "previous" max(id) WHERE -

i have table inserts data when kid checks in summer camp area. if kid < 12 years of age parents barcode must scanned allow kid entry young kids area (<12 years of age).

the table has following columns.

kcid uid id age room barcode date amber 

the data presented this.

kcid uid    id      age     room    barcode date                    amber 25   1      1       30      1000    0001    6/26/2014 1:27:40    0 26   6      1       1       1000    0005    6/26/2014 1:27:40    0 

the problem have need compare dates/hours know if kid entering or leaving camp area , via php send sms parents know kid outside particular area.

i know can retrieve max(kcid) barcode = xxxx , return last inserted row, but, in order me retrieve said information kid must scanned, inserting new row , rendering max(kcid) useless in case.

what need able select max(kcid) barcode = xxxx , select previous row record in barcode = xxxx found. way can compare dates , know if kid leaving or entering particular area.

the easiest solution can think of right have 2 tables (1 entry 1 out) , have camp counselors choose if kid entering or leaving i'm wondering if can use 1 table.

you add column indicating leave / return, , add condition.

e.g.

alter table `table`     add `status` enum('left', 'returned') not null default 'left'; 

a query be

select `kcid`, `barcode` `table` `status` = 'left' order `timefield` desc limit 1