Why should you care?

Deleting ShopNest Order should remove OrderItems — cascade cleans children. Deleting Category should NOT cascade-delete all Products — use Restrict.

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).

modelBuilder.Entity<OrderItem>()
    .HasOne(i => i.Order)
    .WithMany(o => o.Items)
    .HasForeignKey(i => i.OrderId)
    .OnDelete(DeleteBehavior.Cascade);

modelBuilder.Entity<Product>()
    .HasOne(p => p.Category)
    .WithMany(c => c.Products)
    .HasForeignKey(p => p.CategoryId)
    .OnDelete(DeleteBehavior.Restrict);

What happened?

• Cascade on Order–OrderItem deletes line items with order.
• Restrict on Product–Category blocks category delete while products reference it.

Practice next

1. Document business delete rules per relationship.
2. Configure OnDelete explicitly — do not rely on defaults alone.
3. Test delete in SSMS transaction rollback sandbox.
4. Set SetNull on optional FK when principal deleted.
5. Inspect migration FK ON DELETE clause matches Fluent config.

Remember

OnDelete controls dependent row behavior. Cascade suits owned children like OrderItems. Restrict protects referenced principals.

ShopNest order cancellation

Hard delete test Order cascades OrderItems but Restrict prevents Category delete with products.

Outcome: Data rules match finance and catalog team policies.