SQL Server 2019: implementing Duplicate Rows on INNER JOIN with GROUP BY
I just started working with I'm working with unexpected duplicate rows when performing an INNER JOIN between two tables and then applying a GROUP BY clause in SQL Server 2019..... The goal is to get unique customer orders with their total amounts, but I keep getting multiple entries for some customers. Here's the SQL query I'm using: ```sql SELECT c.CustomerID, c.CustomerName, SUM(o.OrderAmount) AS TotalAmount FROM Customers c INNER JOIN Orders o ON c.CustomerID = o.CustomerID GROUP BY c.CustomerID, c.CustomerName; ``` The `Customers` table looks like this: ```sql CREATE TABLE Customers ( CustomerID INT PRIMARY KEY, CustomerName NVARCHAR(100) ); ``` And the `Orders` table: ```sql CREATE TABLE Orders ( OrderID INT PRIMARY KEY, CustomerID INT, OrderAmount DECIMAL(10, 2), FOREIGN KEY (CustomerID) REFERENCES Customers(CustomerID) ); ``` I've populated the `Customers` table with 5 unique customers and the `Orders` table with several entries, including multiple orders for some customers. However, when I run the query, I still see duplicate results for some customer IDs, which I expected the GROUP BY to prevent. I tried adding DISTINCT to the SELECT statement, but it didn't resolve the scenario. I also verified that there are no hidden spaces or case sensitivity issues in the `CustomerName` field. I'm also using SQL Server Management Studio version 18.9.1. Can anyone guide to understand why I'm getting duplicate rows in this scenario? Is there a way to fix this without changing my database schema? The project is a service built with Sql. Has anyone dealt with something similar? I'm coming from a different tech stack and learning Sql. Am I missing something obvious? I've been using Sql for about a year now. Cheers for any assistance!