SQL Query Issue: Filtering Aggregated Data with HAVING Clause

Data and Databases
1

I am facing a challenge with my SQL query, where filtering on an aggregated column using the HAVING clause is causing issues. I attempted to run a modified version, but I still encounter errors. Below is a new code snippet I put together that involves joining three tables and grouping results before applying the filter. I’m looking for insights into why the HAVING condition might fail when summing up the values. Any suggestions on how to resolve this would be greatly appreciated.

SELECT c.contactName, c.contactSurname, SUM(pi.itemCount) AS totalCount
FROM Clients c
JOIN Purchases p ON c.clientID = p.buyerID
JOIN PurchaseItems pi ON p.purchaseID = pi.orderRef
WHERE c.region = 'Germany'
GROUP BY c.contactName, c.contactSurname
HAVING totalCount > 500
ORDER BY c.contactSurname;
2

hey, tried using sum(pi.itemCount) > 500 in the havin clause directly instead of the alias? sometimes sql engines act funky. im wonderin if your joins might be off. what error msgs are u gettin? curious to see if that could be the cause.

3

hey, i had a simlar issue. try using sum(pi.itemCount) in the havng clause directly instead of the alias. it solved it for me. also, double-check your joins aren’t filtering rows earlier than expected. good luck!

4

The issue might be related to alias usage in the HAVING clause rather than the aggregation itself. In some SQL engines, referencing the alias directly in HAVING is not supported, requiring you to use the aggregate function explicitly. I’ve resolved similar issues by modifying the clause to use SUM(pi.itemCount) > 500 instead of the alias. Additionally, verifying that all JOIN conditions correctly align to avoid unintended filtering is important. In a previous case, restructuring the query into a subquery for aggregation helped isolate and resolve the problem.