每次读取DBSET，都会重新连接数据？数据不会缓存吗？

例如下面的代码，

using (NorthDb north = new NorthDb())
            {
                IEnumerable<Product> proList = north.Products.Where(a => a.ProductID > 0);

               
                foreach (Product pro in proList) //连接数据库
                {
                    Category cat = pro.Category; //连接数据库

                    string name = cat.CategoryName;
                }

                foreach (Product pro in proList) //连接数据库
                { 
                    Category cat = pro.Category; //不连接数据库

                    string name = cat.CategoryName;
                }               
            }

public class NorthDb : DbContext
    {
        public DbSet<Product> Products { get; set; }
        public DbSet<Category> Categories { get; set; }

}