SQL: Last_Value() returns wrong result (but First_Value() works fine)

Question

I have a table in SQL Server 2012 as the snapshot shows:

Then I\'m usi

Answer 1

There is nothing wrong with your script, this is a way how partitioning works in SQL server :/. If you change LAST_VALUE to MAX result will be the same. Solution would be:

SELECT A.EmpID,  
       First_Value(A.AverageAmount) OVER (PARTITION BY A.EmpID Order by A.DimYearMonthKey asc) AS  '200901AvgAmount', 
       Last_Value(A.AverageAmount) OVER (PARTITION BY A.EmpID Order by A.DimYearMonthKey ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) AS '201112AvgAmount'  
FROM  Emp_Amt  AS A

There is a great post about it, link. GL!