Taking SUM of values that are obtained from SUM of another column - sql

Question

I have a MSSQL query in which I am taking grandtotal, which is a SUM of values that are obtained by taking SUM.
select
s.name
,SUM(b.dAmount) as total
,SUM(SUM(b.dAmount)) as grandtotal
from t_sales a
left outer join t_cust b on (b.dId=a.id)
where a.custId=#customerId
GROUP BY b.name;
I can get the name and total but grandtotal doesn't return any value. Please let me know what is the correct way to take SUM of values that are SUM of another values.Thanks

Answer 1

Try this:
select
b.name
,SUM(b.dAmount) as total
, SUM(SUM(b.dAmount)) OVER () as grandtotal
from t_sales a
left outer join t_cust b on (b.dId=a.id)
where a.custId=#customerId
GROUP BY b.name;

Answer 2

In MySQL, you can't do this without either using a nested subquery or by using the GROUP BY WITH ROLLUP
For your case, I'd recommend just using the WITH ROLLUP keyword, this will add another row to the result set with the grand total. It will also avoid returning the same total on every row of the set.
SELECT IFNULL(s.name, 'Total'), SUM(b.dAmount) as total
FROM t_sales a
LEFT OUTER JOIN t_cust b ON (b.dId = a.id)
WHERE a.custId = #customerId
GROUP BY b.name WITH ROLLUP;
If you're not directly displaying the results you can remove the IFNULL(s.name, 'Total') bit - the super-aggregate will have nulls on all columns not in the SUM()

Answer 3

You can also try this
create table #t_sales (name varchar(100),amount numeric(18,2))
INSERT INTO #t_sales (name,amount)
values ('A',100.00)
,('B',200.00)
,('C',300.00)
,('C',400.00)
INSERT INTO #t_sales (name,amount)
values ('A',100.00)
,('B',200.00)
,('C',300.00)
,('C',400.00)
SELECT CASE WHEN (GROUPING(name) = 1) THEN 'GRAND TOTAL'
ELSE ISNULL(name, ' ')
END AS [type]
,SUM(amount) AS TOTAL
FROM #t_sales
GROUP BY name WITH ROLLUP