Group by multiple fields (composite key)?

Short answer: var grouped = employees .GroupBy(e => new { e.Department, e.Salary }); var grouped = employees .GroupBy(e => new { e.Department, e.Salary }); var grouped = employees .GroupBy(e => new { e.Department, e.Salary }); var grouped = employees .GroupBy(e => new { e.Department, e.Salary }); var grouped = employees .GroupBy(e => new { e.Department, e.Salary }); var grouped = employees .GroupBy(e => new { e.Department,…

Explain a bit more

e.Salary }); var grouped = employees .GroupBy(e => new { e.Department, e.Salary }); var grouped = employees .GroupBy(e => new { e.Department, e.Salary });

Example code

var grouped = employees .GroupBy(e => new { e.Department, e.Salary }); var grouped = employees .GroupBy(e => new { e.Department, e.Salary }); var grouped = employees .GroupBy(e => new { e.Department, e.Salary }); var grouped = employees .GroupBy(e => new { e.Department, e.Salary }); var grouped = employees .GroupBy(e => new { e.Department, e.Salary }); var grouped = employees .GroupBy(e => new { e.Department, e.Salary }); var grouped = employees .GroupBy(e => new { e.Department, e.Salary }); var grouped = employees .GroupBy(e => new { e.Department, e.Salary });

Real-world example (ShopNest)

A sales report joins orders and customers, then GroupBy(c => c.City) to show revenue per city.

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.