Relationship Using Code first with Existing database
public class Product
    {
        public int ProductId { get; set; }
        public string Name { get; set; }
        public Category Category { get; set; }
    }

    public class Category
    {
        public int CategoryId { get; set; }
        public string Name { get; set; }
        public ICollection<Product> Products { get; set; }
    }

modelBuilder.Entity<Product>()
    .HasMany(x => x.Category)