linq to sql c＃：SubmitChanges（）不更新数据库

Question

下面更新数据库的方法称为UpdateHold（）。该对象的实例使用第二个构造函数。我运行了调试来验证保持对象“thisHold”正在更新表单中正在更改的值。但是当我在提交后查看db对象的值时，我发现它并没有改变，在物理数据库中也是如此。为什么不更新？

using System; 
using System.Collections.Generic; 
using System.ComponentModel; 
using System.Data; 
using System.Drawing; 
using System.Linq; 
using System.Data.Linq; 
using System.Text; 
using System.Windows.Forms; 

namespace Coke_Hold_Database 
{ 
    public partial class frmFGHold : Form 
    { 
     private PINAuthentication cert = new PINAuthentication(); 
     linqCokeDBDataContext db = new linqCokeDBDataContext(); 
     Record_HoldData thisHold; 
     bool isNew; //flag if hold is new or not 


     public frmFGHold() 
     { 
      //constructor for new hold 
      InitializeComponent(); 
      populateLists(); 
      thisHold = new Record_HoldData(); 

      isNew = true; 
      btnEdit.Visible = false; 
     } 

     public frmFGHold(Record_HoldData holdData) 
     { 
      //constructor for existing hold (edit) 
      InitializeComponent(); 
      populateLists(); 
      this.thisHold = holdData; 

      //fill out the form 
      FillForm(); 

      isNew = false; 
      btnEdit.Visible = true; 
     } 

     private void FillForm() 
     { 
      //fill out the form with existing information 

      txtPONumber.Text = thisHold.PO_.ToString(); 
      cboProductionSupervisor.SelectedValue = thisHold.ProductionSupervisor; 
      cboLineNumber.SelectedValue = thisHold.LineNumber; 
      cboQASupervisor.SelectedValue = thisHold.QASupervisor; 
      cboFlavorName.SelectedValue = thisHold.Flavor; 
      cboContainer.Text = thisHold.ContainerType; 
      cboContainerSize.Text = thisHold.ProductSize; 
      cboPackage.Text = thisHold.Package; 
      txtQuantity.Text = thisHold.HoldQty.ToString(); 
      mtbDateCode.Text = thisHold.DateCode; 
      cboDefectiveComponent.Text = thisHold.NonConformingItem; 
      cboDefectReason.Text = thisHold.NonConformance; 
      cboOccuredAt.Text = thisHold.FoundDuring; 
      chkTestRequired.Checked = (bool) thisHold.TestRequired; 
      txaDescription.Text = thisHold.Comments; 
      txaRootCauseAnalysis.Text = thisHold.RootCause; 
     } 

     private void UpdateHoldObject() 
     { 
      thisHold.PO_ = int.Parse(txtPONumber.Text); 
      thisHold.ProductionSupervisor = (int)cboProductionSupervisor.SelectedValue; 
      thisHold.LineNumber = (int) cboLineNumber.SelectedValue; 
      thisHold.QASupervisor = (int) cboQASupervisor.SelectedValue; 
      thisHold.Flavor = (int) cboFlavorName.SelectedValue; 
      thisHold.ContainerType = cboContainer.Text; 
      thisHold.ProductSize = cboContainerSize.Text; 
      thisHold.Package = cboPackage.Text; 
      thisHold.HoldQty = int.Parse(txtQuantity.Text); 
      thisHold.DateCode = mtbDateCode.Text; 
      thisHold.NonConformingItem = cboDefectiveComponent.Text; 
      thisHold.NonConformance = cboDefectReason.Text; 
      thisHold.FoundDuring = cboOccuredAt.Text; 
      thisHold.TestRequired = chkTestRequired.Checked; 
      thisHold.Comments = txaDescription.Text; 
      thisHold.RootCause = txaRootCauseAnalysis.Text; 
     } 

     private void CreateNewHold() 
     { 
      db.Record_HoldDatas.InsertOnSubmit(thisHold); 
      //GenerateHoldNumber() 
      db.SubmitChanges(); 
      MessageBox.Show(this, "Hold submitted!\n\nYou're hold number is " + thisHold.HoldID.ToString(),"Hold #" + thisHold.HoldID.ToString() + " created", MessageBoxButtons.OK, MessageBoxIcon.Information); 
      this.Close(); 
     } 

     private void UpdateHold() 
     { 
      db.SubmitChanges(); 
      MessageBox.Show(this, "Hold #" + thisHold.HoldID.ToString() + " updated.", thisHold.HoldID.ToString() + " updated", MessageBoxButtons.OK, MessageBoxIcon.Information); 
      this.Close(); 
     } 

     private bool ValidateEntry() 
     { 
      //TODO write some frakkin validation 
      return true; 
     } 

     private void GetPIN() 
     { 
      frmPINPrompt pin = new frmPINPrompt(cert); 
      pin.ShowDialog(); 
     } 

     private void SubmitData() 
     { 
      UpdateHoldObject(); 
      GetPIN(); 

      if (ValidateEntry() && cert.authenticated) 
      { 
       try 
       { 
        if (isNew) 
        { 
         thisHold.LabTech = cert.empNumber; 
         thisHold.LastEditBy = cert.empNumber; 
         thisHold.HoldStatus = "Open"; 
         thisHold.DateOpened = DateTime.Now; 
         thisHold.LastEditDate = DateTime.Now; 

         CreateNewHold(); 
        } 
        else 
        { 
         thisHold.LastEditBy = cert.empNumber; 
         thisHold.LastEditDate = DateTime.Now; 

         UpdateHold(); 
        } 
       } 
       catch (Exception ex) 
       { 
        MessageBox.Show(ex.Message); 
       } 
      } 
     } 

     public void populateLists() 
     { 
      //load production names 
      var productionNames = 
       from a in db.LUT_Employees 
       where a.position == "Supervisor" && a.department == "Production" 
       select new { ID = a.ID, Names = a.lastName + ", " + a.firstName }; 

      cboProductionSupervisor.DataSource = productionNames; 
      cboProductionSupervisor.DisplayMember = "Names"; 
      cboProductionSupervisor.ValueMember = "ID"; 

      //load QA names 
      var qaNames = 
       from a in db.LUT_Employees 
       where a.position == "Supervisor" && a.department == "Quality Assurance" 
       select new { ID = a.ID, Names = a.lastName + ", " + a.firstName }; 

      cboQASupervisor.DataSource = qaNames; 
      cboQASupervisor.DisplayMember = "Names"; 
      cboQASupervisor.ValueMember = "ID"; 

      //load flavor names 
      var flavorNames = 
       from a in db.LUT_Flavors 
       select new { ID = a.ID, Flavor = a.flavor }; 

      cboFlavorName.DataSource = flavorNames; 
      cboFlavorName.DisplayMember = "flavor"; 
      cboFlavorName.ValueMember = "ID"; 

      //load line numbers 
      var lineNumbers = 
       (from a in db.LUT_ProductionLines 
       select new { a.lineNumber }).ToList(); 

      cboLineNumber.DataSource = lineNumbers; 
      cboLineNumber.DisplayMember = "LineNumber"; 
      cboLineNumber.ValueMember = "LineNumber"; 
     } 

     private void mtbDateCode_MouseUp(object sender, MouseEventArgs e) 
     { 
      SendKeys.Send("{HOME}"); 
     } 

     private void btnCancel_Click(object sender, EventArgs e) 
     { 
      DialogResult result = MessageBox.Show("Are you sure you want to cancel? All data will be lost!", "Confirm Cancel", MessageBoxButtons.YesNo, MessageBoxIcon.Asterisk); 
      if (result == DialogResult.Yes) 
      { 
       this.Close(); 
      } 
      else { } 
     } 





     private void btnSubmit_Click(object sender, EventArgs e) 
     { 
      SubmitData(); 

     } 

     private void linkAutoFill_LinkClicked(object sender, LinkLabelLinkClickedEventArgs e) 
     { 
      //autogenerage date code 
      mtbDateCode.Text = Etc.BuildDateCode(DateTime.Now,(int)cboFlavorName.SelectedValue,cboContainer.Text,Etc.getDayCode(DateTime.Now),int.Parse(cboLineNumber.Text)); 
     } 

     private void cboContainerSize_SelectedIndexChanged(object sender, EventArgs e) 
     { 
      //load package sizes 
      var packageSizes = 
       from a in db.LUT_Packagings 
       where a.Container == cboContainer.Text && a.Size == cboContainerSize.SelectedValue 
       select new { ID = a.ID, Size = a.Package }; 

      cboPackage.DataSource = packageSizes; 
      cboPackage.DisplayMember = "Size"; 
      cboPackage.ValueMember = "ID"; 

     } 

     private void cboContainer_SelectedIndexChanged(object sender, EventArgs e) 
     { 
      //make container size list 
      var containerSizes = 
       from a in db.LUT_Containers 
       where a.ContainerType == cboContainer.Text 
       select new { ID = a.ID, Size = a.size }; 

      cboContainerSize.DataSource = containerSizes; 
      cboContainerSize.DisplayMember = "Size"; 
      cboContainerSize.ValueMember = "ID"; 

      //load components 
      var defectiveComponents = 
       from a in db.LUT_ContainerComponents 
       where a.Container == cboContainer.Text 
       select new { ID = a.ID, Comp = a.Component }; 

      cboDefectiveComponent.DataSource = defectiveComponents; 
      cboDefectiveComponent.DisplayMember = "Comp"; 
      cboDefectiveComponent.ValueMember = "ID"; 
     } 

     private void btnEdit_Click(object sender, EventArgs e) 
     { 
      //TODO ask verify PIN 
      foreach (Control c in this.Controls) 
      { 
       c.Enabled = true; 
      } 

      btnSubmit.Text = "Update Hold"; 
     } 
    } 
} 

Answer 1

数据库没有更新，因为您要提交的db DataContext的变化，你已经通过构造函数提供的“持有”没有连接到DataContext的。因此，DataContext不能跟踪您对该对象所做的更改。

您可以尝试使用DataContext.Attach，或者，甚至更好的方式是为表单提供加载对象的原始数据上下文。