Interview Question

How can you create a database using Entity Framework Core?

Answer

There are three main approaches to create a database using Entity Framework Core:

1. Using EF Core Migrations

// 1. Create a migration
dotnet ef migrations add InitialCreate

// 2. Apply the migration to create/update database
dotnet ef database update

2. Using EnsureCreated()

using var context = new ApplicationDbContext();
// Creates database if it doesn't exist
context.Database.EnsureCreated();

3. Programmatically with DbContext

public class ApplicationDbContext : DbContext
{
    public DbSet<Customer> Customers { get; set; }
    
    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        // Configure your model here
        modelBuilder.Entity<Customer>()
            .HasKey(c => c.Id);
            
        // Seed initial data
        modelBuilder.Entity<Customer>().HasData(
            new Customer { Id = 1, Name = "John Doe" }
        );
    }
}

// In Program.cs or Startup.cs
public void Configure(IApplicationBuilder app)
{
    using (var scope = app.ApplicationServices.CreateScope())
    {
        var context = scope.ServiceProvider.GetRequiredService<ApplicationDbContext>();
        context.Database.Migrate(); // This will create the database
    }
}

Key Points to Remember 💡

• Migrations are recommended for production environments
• EnsureCreated() is good for testing or prototypes
• Always use transactions for data seeding
• Migrations track schema changes over time

Common Follow-up Questions

1. What’s the difference between EnsureCreated() and Migrations?
2. How do you handle database schema changes?
3. How can you seed initial data to the database?