Read from 3 tables

I pick some data from three tables TEST_DATA, TEST_PARAM and TEST_TEST. When I run the question I get more rows with the same information, (serial number and attribute), except from the date/time column.

How does a SQL question look like to get only the latest value for each pt_param_attr based on the date column? I dont want to have the same serialno. with the same attr. For examle 8775-001 has two attr '4' and four attr '22'. I only want to have the latest for each attr and each serial.
Please Help!

I use Sybase, SQL Anywhere 12

My query:
SELECT pt_test_man_order, pt_test_serial, pt_data_var, pt_param_attr, pt_data_date
FROM test_data,
test_param,
test_test
WHERE pt_test_id = pt_data_test_id
AND pt_data_param_id = pt_param_id
AND ((pt_test_man_order='8775'))
ORDER BY pt_test_serial

I get this answer:

 

First of all, can you put any aliases on your tables in your query? Like this :

SELECT TST.pt_test_man_order,
TST.pt_test_serial,
DATA.pt_data_var,
PRM.pt_param_attr,
DATA.pt_data_date
FROM test_data DATA,
test_param PRM,
test_test TST
WHERE TST.pt_test_id = DATA.pt_data_test_id
AND DATA.pt_data_param_id = PRM.pt_param_id
AND TST.pt_test_man_order = '8775'
ORDER BY TST.pt_test_serial;

We don't know your database, it will help us to understand the problem.

Then, can you explain your need? Can your show us the content of these tables?