Question

I use this query below to get the latest Serial Number that has been added

SELECT 
    SerialNo, 
    MAX(AddDate) AS AddDate
FROM 
    tst_EquipmentItem 
WHERE 
    ControlNo = 'TM-00012'
GROUP BY 
    SerialNo
ORDER BY 
    AddDate

OUTPUT:
SerialNo////AddDate
=======================================
TM-00012////2008-08-05 10:25:00.000

Now in the tst_Equipment table there is a ControlNo column. If I include ControlNo to the above statement I get a different output

OUTPUT
SerialNo///ControlNo///AddDate
====================================================
TM-00012///TM-CGI-F-0027///2004-02-09 08:20:00.000
TM-00012///TM-EN-N-0068///2008-08-05 10:25:00.000

How do I include the ControlNo column without having to put it in the GROUP BY Clause so that I can get the latest ControlNo for each SerialNo?

Answer 1

Without knowing your data, I would do:

select distinct t.serialNo, e.controlNo, t.addDate
from tst_EquipmentItem e
join (
    select serialNo, max(addDate) as addDate
    from tst_EquipmentItem 
    group by serialNo
) t on t.serialNo = e.serialNo and t.addDate = e.addDate