Show all departments even if no employees (outer join) join e in employees on d.Name equals e.Department from eg in empGroup.DefaultIfEmpty() select new { Dept = d.Name, EmpName = eg?.Name?? "No Employee" };

Short answer: var allDepts = from d in departments into empGroup var allDepts = from d in departments into empGroup var allDepts = from d in departments into empGroup var allDepts = from d in departments into empGroup var allDepts = from d in departments into empGroup var allDepts = from d in departments into empGroup var allDepts = from d in departments into empGroup var allDepts = from d in departments into empGroup

Example code

var allDepts = from d in departments into empGroup var allDepts = from d in departments into empGroup var allDepts = from d in departments into empGroup var allDepts = from d in departments into empGroup var allDepts = from d in departments into empGroup var allDepts = from d in departments into empGroup var allDepts = from d in departments into empGroup var allDepts = from d in departments into empGroup

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.