Jeremy Kern Jeremy Kern - 1 year ago 106
SQL Question

select Newest Instead of Distinct

Currently I have a stored proc that returns data from a database table that is populated from an API. The current query is:

Select * From Inventory
where StockNumber in
(select distinct stocknumber)
order by Make

Instead of this I actually need to take the top 1 newest record based on a DateTimeStamp Column as there are often many records with the same stocknumber but different timestamp.

Answer Source

One method is to use a correlated subquery:

Select i.*
From Inventory i
where i.datetime in (select max(i2.datetime)
                     from Inventory i2
                     where i2.stocknumber = i.stocknumber
order by i.Make;

Another method is to use the ANSI standard window function row_number():

select i.*
from (select i.*,
             row_number() over (partition by stocknumber order by datetime desc) as seqnum
      from Inventory i
     ) i
where seqnum = 1;
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