oracle EF core hello world

CREATE TABLE student (
    num int not null,
    name varchar2(200) not null,
    PRIMARY KEY(num)
 );

using Microsoft.EntityFrameworkCore;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
namespace d0001_efc1
{
    class Program
    {
        public class StudentContext : DbContext
        {
            public DbSet<Student>? Students { get; set; }


            protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
            {
                optionsBuilder.UseOracle(@"User Id=test_user;Password=123456;Data Source=(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=127.0.0.1)(PORT=1521))(CONNECT_DATA=(SERVICE_NAME=aaa)))");
            }
        }
        [Table("STUDENT")]
        public class Student
        {
            [Column("NUM")]
            [Key]
            public int num { get; set; }
            [Column("NAME")]
            public string? name { get; set; }


        static void Main(string[] args)
        {
            using (var db = new StudentContext())
            {
                var student = new Student { num = 4, name = "张三" };
                db.Students!.Add(student);
                db.SaveChanges();
            }

            using (var db = new StudentContext())
            {
                var blogs = db.Students;
                foreach (var item in blogs!)
                {
                    Console.WriteLine(item.name);
                        Console.WriteLine(item.num);
                        //Console.WriteLine(item.Url + " has rating " + item.Rating );
                    }
            }
            Console.ReadLine();
        }
    }
    }
}