Finding max date for a concatenated field

Question

I am trying to take a very large product table that has one row per product status and date, and get down to a table that demonstrates the latest status for each product they own.

I think if I concatenate the account and product columns and then use that to find the max date but I'm stumbling with my code. Would appreciate any insight!

Example table

Account	Product	EffectiveDate	Status
10000	Product A	5/1/2021	Live
10000	Product A	9/1/2020	Decomissioned
10000	Product B	12/1/2021	Implementing

My goal output would be:

Account	Product	EffectiveDate	Status
10000	Product A	5/1/2021	Live
10000	Product B	12/1/2021	Implementing

Answer 1

SELECT X.Account,X.Product,X.EffectiveDate,X.Status FROM
(  
   SELECT E.Account,E.Product,E.EffectiveDate,E.Status,
   ROW_NUMBER()OVER(PARTITION BY E.Product ORDER BY E.EffectiveDate DESC)AS XCOL
   FROM Example_table AS E
)X WHERE X.XCOL=1

May be something like this will be suitable

Answer 2

For some DBMS you can use a window function and qualify . On others (SQL Server) you can use top and a window function.

create table T1 (Account int, Product varchar(255), EffectiveDate date, status varchar(255));

insert into T1 (Account,    Product ,   EffectiveDate , "STATUS" ) values
(10000, 'Product A', '2021-05-01', 'Live'),
(10000, 'Product A', '2020-09-01', 'Decomissioned'),
(10000, 'Product B', '2021-12-01', 'Implementing');

-- Snowflake, Teradata, Oracle, others...
select   Account, Product, EffectiveDate, Status
from     T1 
qualify row_number() over (partition by Account, Product order by EffectiveDate desc) = 1
;

-- SQL Server
select top 1 with ties Account, Product, EffectiveDate, Status
from T1
order by row_number() over (partition by Account, Product order by EffectiveDate desc);