SQL query to get the below output - sql-server-2008-r2

Question

Need help for query:
Id Name Balance
1 A 10
2 A -10
3 A 10
4 A 15
5 B 10.5
6 B -10.5
7 B 25
Requirement: I want to remove the balance with +ve and –ve values for each name. I am expecting the below output
Expected results: --
Id Name Balance
1 A 10
2 A 15
3 B 25
Can you please share me SQL query.

Answer 1

Here is one way to do it.
Create dummy data for testing
CREATE TABLE foo (Id INT, Name VARCHAR(50), Balance money);
INSERT INTO foo VALUES (1, 'A', 10);
INSERT INTO foo VALUES (2, 'A', -10);
INSERT INTO foo VALUES (3, 'A', 10);
INSERT INTO foo VALUES (4, 'A', 15);
INSERT INTO foo VALUES (5, 'B', 10.5);
INSERT INTO foo VALUES (6, 'B', -10.5);
INSERT INTO foo VALUES (7, 'B', 25);
1) Create a temp table that has one extra MatchFound column to record whether a match is found.
CREATE TABLE #TempTable(Id int, Name varchar(50), Balance decimal(10,2), MatchFound bit);
INSERT INTO #TempTable (Id, Name, Balance, MatchFound)
SELECT Id, Name, Balance, 0
FROM foo;
2) Loop through the data to find a match for each row. Update MatchFound column if a match is found.
DECLARE #Id INT, #Name VARCHAR(50), #Balance decimal(10,2), #MatchId INT;
DECLARE MyCursor CURSOR FOR SELECT Id, Name, Balance FROM #TempTable ORDER BY Id;
OPEN MyCursor
FETCH NEXT FROM MyCursor INTO #Id, #Name, #Balance
WHILE ##FETCH_STATUS = 0
BEGIN
IF EXISTS (SELECT 1 FROM #TempTable WHERE Id = #Id AND MatchFound = 0)
BEGIN
SET #MatchId = NULL
SELECT TOP 1 #MatchId = Id FROM #TempTable
WHERE Id <> #Id AND Name = #Name AND Balance = #Balance * -1 AND MatchFound = 0
IF #MatchId IS NOT NULL
UPDATE #TempTable SET MatchFound = 1 WHERE Id IN (#Id, #MatchId)
END
FETCH NEXT FROM MyCursor INTO #Id, #Name, #Balance
END
CLOSE MyCursor;
DEALLOCATE MyCursor;
3) Select and return rows that did not have a match
Select Id, Name, Balance From #TempTable Where MatchFound = 0
4) Clean up
drop table #TempTable