Tutorials Entity Framework Core Tutorial
Grouping with LINQ in EF Core
Grouping with LINQ in EF Core: free step-by-step lesson with examples, common mistakes, and interview tips — part of Entity Framework Core Tutorial on Toolliyo Academy.
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Entity Framework Core Tutorial · Lesson 37 of 100
Grouping with LINQ in EF Core
Beginner ✓ → Intermediate → Advanced → Professional
Intermediate · 2 — Data & queries · ~6 min · Module 4: LINQ
What is this?
Grouping aggregates rows with GroupBy — often paired with Sum, Count, Average — EF translates to SQL GROUP BY.
Why should you care?
ShopNest admin dashboard shows revenue per category and units sold per product — grouping belongs on SQL Server.
See it live — copy this example
Paste into a .NET project with EF Core packages, then run with LocalDB/SQL Server (dotnet ef / dotnet run).
var revenueByCategory = await _context.OrderItems
.Include(i => i.Product)
.GroupBy(i => i.Product!.CategoryId)
.Select(g => new
{
CategoryId = g.Key,
Revenue = g.Sum(i => i.Quantity * i.UnitPrice),
Lines = g.Count()
})
.ToListAsync();What happened?
- GroupBy CategoryId collapses line items.
- Sum and Count become SQL aggregates.
- Result is one row per category with totals.
Practice next
- Filter OrderItems by date range before GroupBy.
- Use Select after GroupBy for aggregate shapes only.
- Verify HAVING equivalent via Where after GroupBy if needed.
- Group orders by OrderDate.Date for daily sales chart.
- Add Average(i => i.UnitPrice) to category summary.
Remember
GroupBy maps to SQL GROUP BY. Aggregate with Sum, Count, Average in Select. Filter before group when possible.
ShopNest sales dashboard
Admin panel groups OrderItems by category for yesterday revenue tiles.
Outcome: SQL Server aggregates millions of lines — API returns ten category rows.
Interview prep for this lesson
Practice these questions aloud after reading—each links to a full structured answer.
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