Use Single vs First — what's the difference?

Short answer: >1 ✅ Tip: Use Single when you're sure there will be exactly one result. var onlyHR = employees.SingleOrDefault(e => e.Id == 1); // throws if var firstHR = employees.FirstOrDefault(e => e.Id == 1); // safe

Example code

>1 ✅ Tip: Use Single when you're sure there will be exactly one result. var onlyHR = employees.SingleOrDefault(e => e.Id == 1); // throws if
var firstHR = employees.FirstOrDefault(e => e.Id == 1); // safe

Real-world example (ShopNest)

ShopNest uses LINQ to query orders: filter by date, project to a summary DTO, and order by total—readable C# that becomes SQL under EF Core.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.