How to do grouping, aggregation (Sum, Count, Max, Min) via LINQ?

Short answer: var groupedData = context.Orders .GroupBy(o => o.CustomerId) .Select(g => new { CustomerId = g.Key, TotalOrders = g.Count(), TotalAmount = g.Sum(o => o.Amount), MaxAmount = g.Max(o => o.Amount), MinAmount = g.Min(o => o.Amount) });

Example code

var groupedData = context.Orders .GroupBy(o => o.CustomerId) .Select(g => new { CustomerId = g.Key, TotalOrders = g.Count(), TotalAmount = g.Sum(o => o.Amount), MaxAmount = g.Max(o => o.Amount), MinAmount = g.Min(o => o.Amount) });

Real-world example (ShopNest)

ShopNest’s order service uses EF Core to save an Order and its line items in one SaveChangesAsync() call inside a transaction.

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.