如何在現有行下面的DataTable中添加新行

Question

我試圖在我的DataTable添加一個新行，然后每次單擊按鈕將其綁定到GridView （ Inquiries ）。 當我第一次單擊該按鈕時添加該行。 但是當我嘗試再次點擊它來添加另一行時，它會替換現有的行。

protected void addInquiry_Click(object sender, EventArgs e)
{
      try
      {
             Quantity = QuantityTxt.Text;
             string Details = Request.Form[Products.UniqueID];
             SelectedProduct = Details.Split('!');
             ProductNo = SelectedProduct[0];
             ProductDescription = SelectedProduct[1];
             ProductSapPack = SelectedProduct[2];
             ProductID = SelectedProduct[3];
             DataTable dt = new DataTable();                       
             dt.Columns.AddRange(new DataColumn[5] { 
                                 new DataColumn("ProductID",typeof(int)),
                                 new DataColumn("ProductNo", typeof(string)),
                                 new DataColumn("Description", typeof(string)),
                                 new DataColumn("SapPack",typeof(string)),
                                 new DataColumn("Quantity",typeof(string)),
                                 });

            DataRow dr = dt.NewRow();

            dr[0] = ProductID;
            dr[1] = ProductNo;
            dr[2] = ProductDescription;
            dr[3] = ProductSapPack;
            dr[4] = Quantity;

            dt.Rows.Add(dr);
            Inquiries.DataSource = dt;
            Inquiries.DataBind();
      }

      finally
      {
            QuantityTxt.Text = String.Empty;
            Description.Text = String.Empty;
            SapPack.Text = String.Empty;
            Products.Text = String.Empty;
      }
}

Answer 1

通過將創建的數據表添加到會話狀態來修改代碼，然后在用戶單擊按鈕時嘗試檢索它。

protected void addInquiry_Click(object sender, EventArgs e)
{
     DataTable dt=(DataTable)Session["Inquiry"];
  try
  {
         Quantity = QuantityTxt.Text;
         string Details = Request.Form[Products.UniqueID];
         SelectedProduct = Details.Split('!');
         ProductNo = SelectedProduct[0];
         ProductDescription = SelectedProduct[1];
         ProductSapPack = SelectedProduct[2];
         ProductID = SelectedProduct[3];
         if(dt==null)
         {
             dt= new DataTable();                       
         }             
         dt.Columns.AddRange(new DataColumn[5] { 
                             new DataColumn("ProductID",typeof(int)),
                             new DataColumn("ProductNo", typeof(string)),
                             new DataColumn("Description", typeof(string)),
                             new DataColumn("SapPack",typeof(string)),
                             new DataColumn("Quantity",typeof(string)),
                             });

        DataRow dr = dt.NewRow();

        dr[0] = ProductID;
        dr[1] = ProductNo;
        dr[2] = ProductDescription;
        dr[3] = ProductSapPack;
        dr[4] = Quantity;

        dt.Rows.Add(dr);
        Inquiries.DataSource = dt;
        Inquiries.DataBind();
        Session.Add("Inquiry",dt);
  }
  finally
  {
        QuantityTxt.Text = String.Empty;
        Description.Text = String.Empty;
        SapPack.Text = String.Empty;
        Products.Text = String.Empty;
  }
}

Answer 2

由於您沒有在數據庫中保存數據，因此需要創建Session / ViewState來保存DataTable。

if(Session["Products"] != null)
 dt = (DataTable) Session["Products"]; 
else
 dt = new DataTable(); // For the first time creates a new DataTable otherwise reads from Session variable

----
At the end, save the data to the Session variable:
Session["Products"] = dt;

Answer 3

為我工作的答案是這樣的

protected void addInquiry_Click(object sender, EventArgs e)
{
     DataTable dt=(DataTable)Session["Inquiry"];
  try
  {
         Quantity = QuantityTxt.Text;
         string Details = Request.Form[Products.UniqueID];
         SelectedProduct = Details.Split('!');
         ProductNo = SelectedProduct[0];
         ProductDescription = SelectedProduct[1];
         ProductSapPack = SelectedProduct[2];
         ProductID = SelectedProduct[3];
         if(dt==null)
         {
             dt= new DataTable(); 
             dt.Columns.AddRange(new DataColumn[5] { 
                             new DataColumn("ProductID",typeof(int)),
                             new DataColumn("ProductNo", typeof(string)),
                             new DataColumn("Description", typeof(string)),
                             new DataColumn("SapPack",typeof(string)),
                             new DataColumn("Quantity",typeof(string)),
                             });

         }             


        DataRow dr = dt.NewRow();

        dr[0] = ProductID;
        dr[1] = ProductNo;
        dr[2] = ProductDescription;
        dr[3] = ProductSapPack;
        dr[4] = Quantity;

        dt.Rows.Add(dr);
        Inquiries.DataSource = dt;
        Inquiries.DataBind();
        Session.Add("Inquiry",dt);
  }
  finally
  {
        QuantityTxt.Text = String.Empty;
        Description.Text = String.Empty;
        SapPack.Text = String.Empty;
        Products.Text = String.Empty;
  }
}