Left join with fallback message join e in employees on d.Name equals e.Department into g from emp in g.DefaultIfEmpty() select new { Department = d.Name, Employee = emp?.Name?? "No employee" };

Short answer: var join = from d in departments var join = from d in departments var join = from d in departments var join = from d in departments var join = from d in departments var join = from d in departments var join = from d in departments var join = from d in departments

Example code

var join = from d in departments var join = from d in departments var join = from d in departments var join = from d in departments var join = from d in departments var join = from d in departments var join = from d in departments var join = from d in departments

Real-world example (ShopNest)

ShopNest maps entities to DTOs with .Select(o => new OrderSummaryDto { Id = o.Id, Total = o.Total }) so the API does not leak internal fields.

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.