如何从数据库填充动态下拉列表值？ [英] How to fill dynamic dropdownlist value from database?

问题描述

你好......

我有一个下拉菜单并添加按钮...

当用户点击添加按钮时，它必须再添加一个下拉菜单...所以on。

其中下拉值不是硬编码的，必须从数据库中获取值。

有谁知道怎么做？



我尝试了什么：

Hello...
I have one dropdown and add button...
When user click on add button,it must add one more dropdown..and so on.
Where dropdown value is not hard coded,value must be fetched from database.
Does anyone know how to do this?

What I have tried:

<pre> <asp:GridView ID="Gridview1" runat="server" ShowFooter="true" AutoGenerateColumns="false"  HeaderStyle-CssClass ="hiddencol"  FooterStyle-CssClass="hiddencol"  >
               <Columns>
               <asp:TemplateField>
               <ItemTemplate >
  <asp:Label ID="Label8" runat="server" Text="HOD "></asp:Label>
 <asp:DropDownList ID="dd_hod"  runat="server" >
  <asp:ListItem Text="----------select---------" Value="none"></asp:ListItem>
  </asp:DropDownList>
       <FooterTemplate>
     <asp:Button ID="ButtonAdd" runat="server" Text="Add" OnClick="ButtonAdd_Click" />
                                        </FooterTemplate>
                                          </ItemTemplate>
                                 
                                    </asp:TemplateField>
       </Columns>
                            </asp:GridView>

<pre>private void SetInitialRow()
    {
       // string lit1 = "HOD";

       
        DataTable dt = new DataTable();
        DataRow dr = null;
       // dt.Columns.Add(new DataColumn("HOD", typeof(string)));
        dt.Columns.Add(new DataColumn("Column1", typeof(string)));
        
        // dt.Columns.Add(new DataColumn("fourth", typeof(string)));
        //dt.Columns.Add(new DataColumn("Column8", typeof(string)));

        dr = dt.NewRow();
        //dr["HOD"] = lit1;
        dr["Column1"] = string.Empty;
      
        // dr["fourth"] = lit4;
        // dr["Column8"] = string.Empty;
        dt.Rows.Add(dr);
        //dr = dt.NewRow();

        //Store the DataTable in ViewState
        ViewState["CurrentTable"] = dt;
        Gridview1.DataSource = dt;
        Gridview1.DataBind();
    }

    protected void ButtonAdd_Click(object sender, EventArgs e)
    {
        AddNewRowToGrid();
    }


    private void AddNewRowToGrid()
    {
        int rowIndex = 0;
        //string lit1 = "HOD1";
        

        if (ViewState["CurrentTable"] != null)
        {
            DataTable dtCurrentTable = (DataTable)ViewState["CurrentTable"];
            DataRow drCurrentRow = null;
            if (dtCurrentTable.Rows.Count > 0)
            {
                for (int i = 1; i <= dtCurrentTable.Rows.Count; i++)
                {
                    //extract the TextBox values

                    DropDownList box1 = (DropDownList)Gridview1.Rows[rowIndex].Cells[0].FindControl("dd_hod");
                   
                    drCurrentRow = dtCurrentTable.NewRow();
                   // drCurrentRow["HOD"] = lit1;
                    dtCurrentTable.Rows[i - 1]["Column1"] = box1.Text;
                   
                    rowIndex++;
                }

                dtCurrentTable.Rows.Add(drCurrentRow);
                ViewState["CurrentTable"] = dtCurrentTable;

                Gridview1.DataSource = dtCurrentTable;
                Gridview1.DataBind();
                
               
            }
        }
        else
        {
            Response.Write("ViewState is null");
        }

        //Set Previous Data on Postbacks
        SetPreviousData();
    }


    private void SetPreviousData()
    {
        int rowIndex = 0;
        if (ViewState["CurrentTable"] != null)
        {
            DataTable dt = (DataTable)ViewState["CurrentTable"];
            if (dt.Rows.Count > 0)
            {
                for (int i = 0; i < dt.Rows.Count; i++)
                {
                    DropDownList box1 = (DropDownList)Gridview1.Rows[rowIndex].Cells[0].FindControl("dd_hod");
                  

                    box1.Text = dt.Rows[i]["Column1"].ToString();
                  
                    // box4.Text = dt.Rows[i]["Column8"].ToString();
                    rowIndex++;
                }
            }
        }
    }

推荐答案

您是否尝试过搜索Google？ asp.net动态下拉列表 [ ^ ]



有很多您可以使用的示例如下：

* 在ASP.Net中创建动态DropDownList控件 [ ^ ]

* ASP NET与C＃动态下拉列表 - YouTube [ ^ ]

* 如何在Asp.net制作国家，州，城市下拉列表 - YouTube [ ^ ]

Have you tried searching Google? asp.net dynamic dropdownlist[^]

There are many examples available to you, here are 3:
* Creating Dynamic DropDownList Controls in ASP.Net[^]
* ASP NET with C# Dynamic Dropdownlist - YouTube[^]
* How to make Country,State,City dropdownlist in Asp.net - YouTube[^]

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