SQL Server 2008 Reporting: Sum of Max of group - sql

Question

I have a table like this in the report designer:
Category: 1 2 3 4 Total
Max Amount: x y z c ?
I need to get the total of Max Amount, but expressions will not let me take Sum(Max(amount)), and the add total is disabled for this cell.
The max amount row is an expression that takes the max of each category. The source data has repeated values, so I just take the max. For example:
Category Amount
1 4.6
1 4.6
1 4.6
2 5
3 4
Other columns in the table are different, but amount will be the same so I cannot only select distinct values.

Answer 1

Maybe something like this:
SELECT
SUM(t1.maxAmout)
FROM
(
SELECT
MAX(t.Amout) AS maxAmout,
t.Category
FROM
yourTable AS t
GROUP BY
t.Category
) AS t1
You can also do it like this. If you are using sql server 2005+:
SELECT
pvt.[1],
pvt.[2],
pvt.[3],
(
pvt.[1]+
pvt.[2]+
pvt.[3]
) AS Total
FROM
(
SELECT
t.Category,
t.Amout
FROM
yourTable AS t
) AS SourceTable
PIVOT
(
MAX(Amout)
FOR Category IN([1],[2],[3])
) AS pvt
EDIT
If you have a 1000 categories. Then a dynamic pivot would be the best solution. So like this:
Test data
CREATE TABLE #T
(
Category INT,
Amout FLOAT
)
INSERT INTO #T
VALUES
(1,4.6),
(1,4.6),
(1,4.6),
(2,5),
(3,4)
Unique column names
DECLARE #cols VARCHAR(MAX)
DECLARE #colsTotal VARCHAR(MAX)
;WITH CTE
AS
(
SELECT
ROW_NUMBER() OVER(PARTITION BY t.Category ORDER BY t.Amout) AS RowNbr,
t.*
FROM
#T AS t
)
SELECT #cols = COALESCE(#cols + ','+QUOTENAME(Category),
QUOTENAME(Category)),
#colsTotal=COALESCE(#colsTotal + '+ISNULL('+QUOTENAME(Category)+',0)',
'ISNULL('+QUOTENAME(Category)+',0)')
FROM
CTE
WHERE
CTE.RowNbr=1
ORDER BY
Category
Dynamic pivot
DECLARE #query NVARCHAR(4000)=
N'SELECT
'+#cols+',
(
'+#colsTotal+'
) AS Total
FROM
(
SELECT
t.Category,
t.Amout
FROM
#T AS t
) AS SourceTable
PIVOT
(
MAX(Amout)
FOR Category IN('+#cols+')
) AS pvt'
EXECUTE(#query)

Answer 2

WITH
aggregate
AS
(
SELECT
category,
MAX(amount) AS max_amount
FROM
yourTable
GROUP BY
category
)
SELECT
MAX(CASE WHEN category = 1 THEN max_amount ELSE NULL END) AS [1],
MAX(CASE WHEN category = 2 THEN max_amount ELSE NULL END) AS [2],
MAX(CASE WHEN category = 3 THEN max_amount ELSE NULL END) AS [3],
MAX(CASE WHEN category = 4 THEN max_amount ELSE NULL END) AS [4],
SUM(max_amount) AS [total]
FROM
aggregate

Answer 3

The following returns a single value:
SELECT DISTINCT SUM(MAX(Amount)) OVER ()
FROM atable
GROUP BY Category
You could use this as a subquery calculating the value of the Total column.
Alternatively, TOP (1) could be used instead of DISTINCT (don't know why I couldn't think of it before):
SELECT TOP (1) SUM(MAX(Amount)) OVER ()
FROM atable
GROUP BY Category