C# 尝试创建数据库代码优先时，对象引用未设置为对象异常的实例

当我尝试添加新学生时，我得到的对象引用未设置为对象的实例，但学生不为null

我正在尝试使用实体创建mysql数据库：

 static void Main(string[] args)
        {
            using (var db =new MySqlTest())
            {
                var s = new Student() {id = 1,num = 9};
                db.Student.Add(s);
                db.SaveChanges();
            }
    }

      public class Student
        {
            [Key]
            public long id { get; set; }
            public long num { get; set; }
        }

        [DbConfigurationType(typeof(MySql.Data.Entity.MySqlEFConfiguration))]
        public class MySqlTest : DbContext
        {
            public DbSet<Student> Student { get; set; }
        }

---

不，这是一个有趣的问题。。。对不起，复本弄错了。那么我对调用

db.Student.Add

时

db.Student.Add

不为空的理解是否正确？你有我们的堆栈跟踪吗？是的，我添加了它你可以看欢迎堆栈溢出！我编辑了你问题的主体，因此内容不在引号中。除非你特别引用了一些东西，否则这是不必要的。我还设置了代码格式错误的格式（前面有4个空格），这样更容易阅读。很好的一天！

   ב-  MySql.Data.MySqlClient.MySqlProviderServices.GetDbProviderManifestToken(DbConnection connection)    ב-  System.Data.Entity.Core.Common.DbProviderServices.GetProviderManifestToken(DbConnection connection)    ב-  MySql.Data.Entity.MySqlManifestTokenResolver.ResolveManifestToken(DbConnection connection)    ב-  System.Data.Entity.Utilities.DbConnectionExtensions.GetProviderInfo(DbConnection connection, DbProviderManifest& providerManifest)    ב-  System.Data.Entity.DbModelBuilder.Build(DbConnection providerConnection)    ב-  System.Data.Entity.Internal.LazyInternalContext.CreateModel(LazyInternalContext internalContext)    ב-  System.Data.Entity.Internal.RetryLazy`2.GetValue(TInput input)    ב-  System.Data.Entity.Internal.LazyInternalContext.InitializeContext()    ב-  System.Data.Entity.Internal.InternalContext.GetEntitySetAndBaseTypeForType(Type entityType)    ב-  System.Data.Entity.Internal.Linq.InternalSet`1.Initialize()    ב-  System.Data.Entity.Internal.Linq.InternalSet`1.get_InternalContext()   ב-  System.Data.Entity.Internal.Linq.InternalSet`1.ActOnSet(Action action, EntityState newState, Object entity, String methodName)    ב-  System.Data.Entity.Internal.Linq.InternalSet`1.Add(Object entity)    ב-  System.Data.Entity.DbSet`1.Add(TEntity entity)    ב-  MySqlWithEF.Program.Main(String[] args) ב- C:\Users\X7\Desktop\MyExampls C#\MySqlWithEF\Program.cs:שורה 24    ב-  System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)    ב-  System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)    ב-  Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()    ב-  System.Threading.ThreadHelper.ThreadStart_Context(Object state)    ב-  System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)    ב-  System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)    ב-  System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)    ב-  System.Threading.ThreadHelper.ThreadStart()