SQL - Group by to get sum but also return a row if the sum is 0 - sql

Question

I have the following table:
ID BuyOrSell Total
4 B 10
4 B 11
4 S 13
4 S 29
8 B 20
9 S 23
What I am trying to do is to have sum of B and S columns for each ID and if there is not a B or S for an ID have a row with 0, so expected output would be
ID BuyOrSell Total
4 B 21
4 S 42
8 B 20
8 S 0
9 S 23
9 B 0
I have tried this and it is kind of doing what I am after but not exactly:
DECLARE #Temp Table (ID int, BuyOrSell VARCHAR(1), charge Decimal)
INSERT INTO #Temp
SELECT 4, 'B', 10 UNION ALL
SELECT 4, 'B', 11 UNION ALL
SELECT 4, 'S', 13 UNION ALL
SELECT 4, 'S', 29 UNION ALL
SELECT 8, 'B', 20 UNION ALL
SELECT 9, 'S', 23
;With Results AS
(
SELECT ID,
BuyOrSell,
SUM(charge) AS TOTAL
FROM #Temp
Group by ID, BuyOrSell
)
Select t.*,max(
case when BuyOrSell = 'B' then 'Bfound'
end) over (partition by ID) as ref
,max(
case when BuyOrSell = 'S' then 'Sfound'
end) over (partition by ID) as ref
FROM Results t;
Thanks

Answer 1

Try this:
;WITH CTE(ID, BuyOrSell) AS(
SELECT
ID, T.BuyOrSell
FROM #Temp
CROSS JOIN(
SELECT 'B' UNION ALL SELECT 'S'
)T(BuyOrSell)
GROUP BY ID, T.BuyOrSell
)
SELECT
C.ID,
C.BuyOrSell,
Total = ISNULL(SUM(T.charge), 0)
FROM CTE C
LEFT JOIN #Temp T
ON T.ID = C.ID
AND T.BuyOrSell = C.BuyOrSell
GROUP BY C.ID, C.BuyOrSell
ORDER BY C.ID, C.BuyOrSell

Answer 2

#03Usr, despite that your question has been answered, please try this:
SELECT two.ID,
two.BuyOrSell,
ISNULL (one.Total, 0) Total
FROM
(SELECT ID,
BuyOrSell,
SUM (Total) Total
FROM #Temp
GROUP BY ID, BuyOrSell) one
LEFT OUTER JOIN
(SELECT ID,
BuyOrSell
FROM #Temp
GROUP BY ID,
BuyOrSell) two
ON one.ID = two.ID
AND one.BuyOrSell = two.BuyOrSell;

Answer 3

Here is a solution with tricky join:
SELECT t1.ID,
v.l as BuyOrSell,
SUM(CASE WHEN t1.BuyOrSell = v.l THEN t1.charge ELSE 0 END) AS Total
FROM #Temp t1
JOIN (VALUES('B'),('S')) v(l)
ON t1.BuyOrSell = CASE WHEN EXISTS(SELECT * FROM #Temp t2
WHERE t2.ID = t1.ID AND t2.BuyOrSell <> t1.BuyOrSell)
THEN v.l ELSE t1.BuyOrSell END
GROUP BY t1.ID, v.l
ORDER BY t1.ID, v.l
Output:
ID l Total
4 B 21
4 S 42
8 B 20
8 S 0
9 B 0
9 S 23