Sum of 2 columns if row exists in Table 2 - SQL - sql

Question

CREATE TABLE #Details
(
SName VARCHAR(20),
PName VARCHAR(20),
SoldCount INT,
Value INT
)
CREATE TABLE #DetailsException
(
ExSName VARCHAR(20),
ExPName VARCHAR(20)
)
INSERT INTO #Details(SName, PName, SoldCount,Value) VALUES ('Store 1', 'Product 1', 10,400)
INSERT INTO #Details(SName, PName, SoldCount,Value) VALUES ('Store 1', 'Product 3', 3,500)
INSERT INTO #Details(SName, PName, SoldCount,Value) VALUES ('Store 2', 'Product 1', 8,30)
INSERT INTO #Details(SName, PName, SoldCount,Value) VALUES ('Store 2', 'Product 2', 10,25)
INSERT INTO #Details(SName, PName, SoldCount,Value) VALUES ('Store 2', 'Product 2', 23,120)
INSERT INTO #Details(SName, PName, SoldCount,Value) VALUES ('Store 4', 'Product 1', 23,50)
INSERT INTO #Details(SName, PName, SoldCount,Value) VALUES ('Store 4', 'Product 3', 10,50)
INSERT INTO #Details(SName, PName, SoldCount,Value) VALUES ('Store 4', 'Product 5', 7,200)
INSERT INTO #Details(SName, PName, SoldCount,Value) VALUES ('Store 5', 'Product 1', 10,100)
INSERT INTO #Details(SName, PName, SoldCount,Value) VALUES ('Store 5', 'Product 1', 24,240)
INSERT INTO #DetailsException(ExSName, ExPName) VALUES ('Store 2', 'Product 2')
INSERT INTO #DetailsException(ExSName, ExPName) VALUES ('Store 4', 'Product 5')
SELECT SName, PName, **CASE WHEN EXISTS(SELECT 1 FROM #DetailsException WHERE ExSName = SName AND ExPName = PNAme ) THEN 0 ELSE SUM(SoldCount) END AS SoldCount**, SUM(Value) AS Value
FROM #Details
GROUP BY SNAME, PNAME
ORDER BY SNAME, PNAME
The result set is correct. Although I want to know if there any other optimized way of writing it in SQL. Since both the tables will grow extremely large in size.
Thanks.

Answer 1

I think I would be more inclined to write this as a LEFT JOIN:
SELECT d.SName, d.PName,
SUM(CASE WHEN de.ExSname IS NOT NULL THEN 0 ELSE SoldCount END) AS SoldCount,
SUM(Value) AS Value
FROM #Details d LEFT JOIN
#DetailsException de
ON de.ExSName = d.SName AND de.ExPName = d.PNAme
GROUP BY d.SNAME, d.PNAME
ORDER BY d.SNAME, d.PNAME;
However, your method is fine.

Answer 2

Considering the ExSName, ExPName is unique in
Here is another way using LEFT JOIN.
SELECT SName,
PName,
Sum(CASE
WHEN de.ExSName IS NULL THEN ( SoldCount )
ELSE 0
END) AS SoldCount,
Sum(Value) AS Value
FROM #Details d
LEFT JOIN (select distinct ExSName,ExPName from #DetailsException) de
ON de.ExSName = d.SName
AND de.ExPName = d.PNAme
GROUP BY SNAME,
PNAME
ORDER BY SNAME,
PNAME
Check the performance by running the queries. You can create Non-clustered index on SName,PNAme column to improve the performance
CREATE NONCLUSTERED INDEX IX_details_temp
ON #Details (SNAME, PNAME)
include (SoldCount, Value);
Added covering index (SoldCount, Value) to avoid Clustered/Heap lookup. Note, Index will be useful only if you are going to filter records from #details table. And for #DetailsException table creating the below index could be helpful
CREATE NONCLUSTERED INDEX IX_DetailsException_temp
ON #DetailsException (ExSName, ExPName)