SQL Server 2016: Inconsistent results when using conditional aggregation with GROUP BY
I've looked through the documentation and I'm still confused about I tried several approaches but none seem to work. I'm working with an scenario with my SQL query that uses conditional aggregation combined with a GROUP BY clause in SQL Server 2016. The query is intended to summarize data from a sales table, but I am getting inconsistent row counts depending on how I structure the CASE statements in the SELECT clause. Here’s the query I have written: ```sql SELECT SalesPersonID, SUM(CASE WHEN SaleAmount > 1000 THEN SaleAmount ELSE 0 END) AS HighValueSales, SUM(CASE WHEN SaleAmount <= 1000 THEN SaleAmount ELSE 0 END) AS LowValueSales FROM Sales GROUP BY SalesPersonID; ``` The question I’m working with is that the `HighValueSales` and `LowValueSales` columns sometimes show incorrect totals when there are NULL values in the `SaleAmount` field. Specifically, if a salesperson has no sales recorded, they don’t appear in the results at all. I need to ensure that every salesperson is represented in the results, even those with no sales, showing `0` for both columns where applicable. I tried using a LEFT JOIN with another query that selects all salespeople to ensure that missing entries are included, but that just complicates the logic and still does not yield the expected results: ```sql SELECT sp.SalesPersonID, COALESCE(SUM(CASE WHEN s.SaleAmount > 1000 THEN s.SaleAmount END), 0) AS HighValueSales, COALESCE(SUM(CASE WHEN s.SaleAmount <= 1000 THEN s.SaleAmount END), 0) AS LowValueSales FROM SalesPeople sp LEFT JOIN Sales s ON sp.SalesPersonID = s.SalesPersonID GROUP BY sp.SalesPersonID; ``` This still leaves me with `NULL` values for salespeople with no sales. I also considered using `ISNULL()` and `COALESCE()` around the `SaleAmount` in the first query, but it doesn’t resolve the scenario of salespeople disappearing from the final output. I would appreciate any insights or solutions to ensure all salespeople show up in my results with accurate zero values where applicable. Am I missing a key detail in my aggregation or join logic? I'm working on a application that needs to handle this. Thanks, I really appreciate it!