不允许从数据类型 nvarchar 到 varbinary(max) 的隐式转换，上传文件

Question

上传文件时出现此错误，即使 SQL 中的列数据类型已经是varbinary 。 我不知道为什么我的参数@FileUpload说的是nvarchar 。 由于我正在使用数据表 function 所以它可以很容易地整体存储并发送到数据库，我也在使用UserDefinedTableType并且我的数据类型已经是varbinary 。

  public ActionResult UpdateClearanceItems(string TranNo, string CompanyID, string AtmCard, string FleetCard, string HmoCard,
          string  Uniform, string RSA, string EducationBenefitsRSA, string AmaBankLoan, string UsedSL,
          string ProratedSL, string KingsTreat, string LastPayroll, string OthersHr, string remarksCompanyID, 
          string remarksAtmCard, string remarksFleetCard, string remarksHmoCard, string remarksUniform, 
          string remarksRSA, string remarksEducationBenefitsRSA , string remarksAmaBankLoan, string remarksUsedSL, 
          string remarksProratedSL, string remarksKingsTreat, string remarksLastPayroll, string remarksOthersHr,
          HttpPostedFileBase[] FileUpload)
    {
        dynamic user = Session["UserProfile"];
        string UserID = user[0].UserID.ToString();

        DataTable dtItems = new DataTable();
        dtItems.Columns.Add("FileName", typeof(string));
        dtItems.Columns.Add("ContentType", typeof(string));
        dtItems.Columns.Add("Data", typeof(string));

        foreach (var file in FileUpload)
        {
            byte[] bytes;

            using (BinaryReader br = new BinaryReader(file.InputStream))
            {
                bytes = br.ReadBytes(file.ContentLength);
            }

            dtItems.Rows.Add(file.FileName, file.ContentType, bytes);

        }

        using (SqlConnection con = new SqlConnection(GlobalFunction.GetConnection("PayrollConnect")))
        {
            con.Open();

            try
            {
                SqlCommand cmd = new SqlCommand("spm_EmpClearancePending", con);
                cmd.CommandTimeout = 1000000;
                cmd.CommandType = CommandType.StoredProcedure;
                cmd.Parameters.AddWithValue("@TranNo", TranNo.ToString());
                cmd.Parameters.AddWithValue("@UserID", UserID.ToString());
                cmd.Parameters.AddWithValue("@CompanyID", CompanyID.ToString());
                cmd.Parameters.AddWithValue("@AtmCard", AtmCard.ToString());
                cmd.Parameters.AddWithValue("@FleetCard", FleetCard.ToString());
                cmd.Parameters.AddWithValue("@HmoCard", HmoCard.ToString());
                cmd.Parameters.AddWithValue("@Uniform", Uniform.ToString());
                cmd.Parameters.AddWithValue("@RSA", RSA.ToString());
                cmd.Parameters.AddWithValue("@EducationBenefitsRSA", EducationBenefitsRSA.ToString());
                cmd.Parameters.AddWithValue("@AmaBankLoan", AmaBankLoan.ToString());
                cmd.Parameters.AddWithValue("@UsedSL", UsedSL.ToString());
                cmd.Parameters.AddWithValue("@ProratedSL", ProratedSL.ToString());
                cmd.Parameters.AddWithValue("@KingsTreat", KingsTreat.ToString());
                cmd.Parameters.AddWithValue("@LastPayroll", LastPayroll.ToString());
                cmd.Parameters.AddWithValue("@OthersHr", OthersHr.ToString());
                cmd.Parameters.AddWithValue("@remarksCompanyID", remarksCompanyID.ToString());
                cmd.Parameters.AddWithValue("@remarksAtmCard", remarksAtmCard.ToString());
                cmd.Parameters.AddWithValue("@remarksFleetCard", remarksFleetCard.ToString());
                cmd.Parameters.AddWithValue("@remarksHmoCard", remarksHmoCard.ToString());
                cmd.Parameters.AddWithValue("@remarksUniform", remarksUniform.ToString());
                cmd.Parameters.AddWithValue("@remarksRSA", remarksRSA.ToString());
                cmd.Parameters.AddWithValue("@remarksEducationBenefitsRSA", remarksEducationBenefitsRSA.ToString());
                cmd.Parameters.AddWithValue("@remarksAmaBankLoan", remarksAmaBankLoan.ToString());
                cmd.Parameters.AddWithValue("@remarksUsedSL", remarksUsedSL.ToString());
                cmd.Parameters.AddWithValue("@remarksProratedSL", remarksProratedSL.ToString());
                cmd.Parameters.AddWithValue("@remarksKingsTreat", remarksKingsTreat.ToString());
                cmd.Parameters.AddWithValue("@remarksLastPayroll", remarksLastPayroll.ToString());
                cmd.Parameters.AddWithValue("@remarksOthersHr", remarksOthersHr.ToString());

                cmd.Parameters.AddWithValue("@FileUpload"  ,dtItems);

                cmd.ExecuteNonQuery();
            }
            catch(Exception err)
            { }
        }

        return RedirectToAction("ClearanceDashboard", "Clearance", new { Message = "Done" });
    }

Answer 1

数据表中"Data"列的类型不应为string ，而应为byte[] - 更改此：

 dtItems.Columns.Add("Data", typeof(string));

对此：

 dtItems.Columns.Add("Data", typeof(byte[]));