ASP.NET Core with EPPlus | Date Range as Request API (.NET 9 + EF Core)

In this video, I add a Student Registration Excel report to our ASP.NET Core (.NET 9) Web API. The user picks a date range and gets an Excel file with every student registered in that period, including their current apply status. What is cover: Extending an existing report module instead of starting from scratch Required date filters (and why the request dates are nullable) The end-date bug: why "CreatedAt - ToDate" silently drops the last day, and the fix Looking up a status name from a separate table with a subquery (works like a LEFT JOIN, no missing rows) Building a 26-column Excel file with EPPlus without column mix-ups Styled headers, auto-fit columns, text dates, and a file name with the date range Returning the file as base64 from a Web API Validation: required dates and backwards ranges Tech: .NET 9, ASP.NET Core Web API, EF Core 9, SQL Server, EPPlus, N-tier architecture (Controller → Service → Repository) #dotnet #aspnetcore #efcore #csharp #excel #epplus #webapi #backend