Oversætte MySQL join til SQL Server-syntaks?

WITH Data AS
(
 SELECT ROW_NUMBER() OVER (PARTITION BY ID ORDER BY Date DESC) AS Row_Number,
 ID,
 AverageValue
 FROM Table
)
SELECT * FROM Data WHERE Row_Number = 1

Sådan skal du gøre det i SQL Server. Det gør "sidste/første/maks./min./største-n-pr. gruppe" let som en kage.

PARTITION BY søgeord her er lig med din GROUP BY sætning og ORDER BY her ville oversætte til MAX aggregatfunktion, du brugte i MySQL

Ved at bruge dette vil du gøre nogle smarte ting som:

WITH Data AS
    (
     SELECT ROW_NUMBER() OVER (PARTITION BY ID ORDER BY Date DESC) AS Row_Number,
     ID,
     AverageValue
     FROM Table
    )

SELECT Newest.ID, 
Newest.AverageValue, 
(Newest.AverageValue - Next_Newest.AverageValue) AS AverageValue_Change,
Newest.Date
 FROM Data Newest
LEFT OUTER JOIN Data Next_Newest 
 ON Newest.Row_Number+1 = Next_Newest.Row_Number
AND Newest.ID = Next_Newest.ID 

WHERE Newest.Row_Number=1