SQL Server: Issues with CROSS APPLY and Nested Queries Returning Unexpected Results
I tried several approaches but none seem to work. I need help solving I just started working with I'm stuck on something that should probably be simple. I'm working with SQL Server 2019 and trying to utilize `CROSS APPLY` to join a table with a nested query, but I'm encountering unexpected results. I have two tables: `Employees` and `Projects`. I want to return each employee's details along with their most recent project. Here's the query I'm using: ```sql SELECT e.EmployeeID, e.Name, p.ProjectName FROM Employees e CROSS APPLY ( SELECT TOP 1 p.ProjectName FROM Projects p WHERE p.EmployeeID = e.EmployeeID ORDER BY p.StartDate DESC ) AS p; ``` This query should give me each employee's name along with their latest project based on the `StartDate`. However, I am getting duplicate rows for employees who have multiple projects. For example, if an employee has two projects, the query returns the employee's details for each project instead of just the most recent one. I've verified that the `TOP 1` clause is working correctly, but the duplicates still appear. I tried using a `ROW_NUMBER()` CTE to filter the results like this: ```sql WITH RankedProjects AS ( SELECT p.ProjectName, p.EmployeeID, ROW_NUMBER() OVER(PARTITION BY p.EmployeeID ORDER BY p.StartDate DESC) AS rn FROM Projects p ) SELECT e.EmployeeID, e.Name, rp.ProjectName FROM Employees e JOIN RankedProjects rp ON e.EmployeeID = rp.EmployeeID WHERE rp.rn = 1; ``` This works as expected and gives me the correct result, but I'm wondering why my initial `CROSS APPLY` approach didn't yield the correct output. Is there something I'm missing about how `CROSS APPLY` behaves with nested queries? Any insights or best practices would be greatly appreciated! This is part of a larger CLI tool I'm building. Any suggestions would be helpful. I'm coming from a different tech stack and learning Sql. Am I missing something obvious? This is for a service running on Linux. Any help would be greatly appreciated!