Selecting SUM of TOP 2 values within a table with multiple GROUP in SQL

Question

I\'ve been playing with sets in SQL Server 2000 and have the following table structure for one of my temp tables (#Periods):

    RestCTR     HoursCTR    Duration          


        

Answer 1

SQL 2000 does not have CTE's, nor ROW_NUMBER().
Correlated subqueries can need an extra step when using group by.

This should work for you:

SELECT 
    F.HoursCTR,
    MAX (F.LongestBreaks) AS LongestBreaks -- Dummy max() so that groupby can be used.
FROM
    (
        SELECT 
            Pm.HoursCTR, 
            (
                SELECT 
                    COALESCE (SUM (S.Duration), 0)    
                FROM 
                    (
                        SELECT TOP 2    T.Duration
                        FROM            #Periods    AS T
                        WHERE           T.HoursCTR  = Pm.HoursCTR 
                        AND             T.Rest      = 1
                        ORDER BY        T.Duration  DESC
                    ) AS S
             ) AS LongestBreaks
        FROM
            #Periods AS Pm
    ) AS F
GROUP BY
    F.HoursCTR