向Datatable添加行，无论我添加多少次，都是一行，这是怎么回事啊？

Question

    protected void Page_Load(object sender, EventArgs e)
    {
        table_black.Visible = false;
    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        DataTable dt = new DataTable();
        DataColumn bianhao1 = new DataColumn("bianhao", Type.GetType("System.String"));
        DataColumn mingcheng1 = new DataColumn("mingcheng", Type.GetType("System.String"));
        DataColumn yanse1 = new DataColumn("yanse", Type.GetType("System.String"));
        DataColumn chima1 = new DataColumn("chima", Type.GetType("System.String"));
        DataColumn shuliang1 = new DataColumn("shuliang", Type.GetType("System.String"));
        dt.Columns.Add(bianhao1);
        dt.Columns.Add(mingcheng1);
        dt.Columns.Add(yanse1);
        dt.Columns.Add(chima1);
        dt.Columns.Add(shuliang1);         DataRow _newRow = dt.NewRow();
        _newRow["bianhao"] = bianhao.Text.ToString();
        _newRow["mingcheng"] = bianhao.Text.ToString();
        _newRow["yanse"] = bianhao.Text.ToString();
        _newRow["chima"] = bianhao.Text.ToString();
        _newRow["shuliang"] = bianhao.Text.ToString();
        dt.Rows.Add(_newRow);
        GridView1.DataSource = dt;
        GridView1.DataBind();
        table_black.Visible = Visible;
    }

Answer 1

你每次点击，都会执行DataTable dt = new DataTable(); 
创建一个新DataTable ，行数是0 ，然后dt.Rows.Add(_newRow); 
添加了一行，所以总是添加一行。把DataTable dt 声明为全局变量就可以了

Answer 2

咋定义？？？我放在Page_Load里面，下面就又出错了。

Answer 3

可是具体怎么声明啊 晕啊。。我已经放在Page_Load里面了。可是说下面的dt出错。

Answer 4

    DataTable dt = new DataTable();     protected void Page_Load(object sender, EventArgs e) 
    { 
        table_black.Visible = false; 
    } 
    protected void Button1_Click(object sender, EventArgs e) 
    { 
        
        DataColumn bianhao1 = new DataColumn("bianhao", Type.GetType("System.String")); 
        DataColumn mingcheng1 = new DataColumn("mingcheng", Type.GetType("System.String")); 
        DataColumn yanse1 = new DataColumn("yanse", Type.GetType("System.String")); 
        DataColumn chima1 = new DataColumn("chima", Type.GetType("System.String")); 
        DataColumn shuliang1 = new DataColumn("shuliang", Type.GetType("System.String")); 
        dt.Columns.Add(bianhao1); 
        dt.Columns.Add(mingcheng1); 
        dt.Columns.Add(yanse1); 
        dt.Columns.Add(chima1); 
        dt.Columns.Add(shuliang1);         DataRow _newRow = dt.NewRow(); 
        _newRow["bianhao"] = bianhao.Text.ToString(); 
        _newRow["mingcheng"] = bianhao.Text.ToString(); 
        _newRow["yanse"] = bianhao.Text.ToString(); 
        _newRow["chima"] = bianhao.Text.ToString(); 
        _newRow["shuliang"] = bianhao.Text.ToString(); 
        dt.Rows.Add(_newRow); 
        GridView1.DataSource = dt; 
        GridView1.DataBind(); 
        table_black.Visible = Visible; 
    }

Answer 5

把DataTable dt 声明为全局变量就可以了

Answer 6

DataColumn  好像要放到Load中了  不然点一下Button 又会追加列

Answer 7

DataTable dt = (DataTable)GridView1.DataSource ; 
if(dt==null)   dt = new DateTable();在button里这么声明就可以了

Answer 8

你每次都new一个新的DataTable当然是只有一行喽

Answer 9

我现在这样了，可是还是一行public partial class admin_Admin_SubmitReturnAdd : System.Web.UI.Page
{
    DataTable dt = new DataTable();
    protected void Page_Load(object sender, EventArgs e)
    {
        table_black.Visible = false;
        DataColumn bianhao1 = new DataColumn("bianhao", Type.GetType("System.String"));
        DataColumn mingcheng1 = new DataColumn("mingcheng", Type.GetType("System.String"));
        DataColumn yanse1 = new DataColumn("yanse", Type.GetType("System.String"));
        DataColumn chima1 = new DataColumn("chima", Type.GetType("System.String"));
        DataColumn shuliang1 = new DataColumn("shuliang", Type.GetType("System.String"));
        dt.Columns.Add(bianhao1);
        dt.Columns.Add(mingcheng1);
        dt.Columns.Add(yanse1);
        dt.Columns.Add(chima1);
        dt.Columns.Add(shuliang1);
    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        DataRow _newRow = dt.NewRow();
        _newRow["bianhao"] = bianhao.Text.ToString();
        _newRow["mingcheng"] = bianhao.Text.ToString();
        _newRow["yanse"] = bianhao.Text.ToString();
        _newRow["chima"] = bianhao.Text.ToString();
        _newRow["shuliang"] = bianhao.Text.ToString();
        dt.Rows.Add(_newRow);
        GridView1.DataSource = dt;
        GridView1.DataBind();
        table_black.Visible = Visible;
    }
}

Answer 10

因为你每次走完button里的代码之后，再进来dt还是没有行的
你用10楼的方法就好了

Answer 11

加
if(!IsPostBck)
{
//定义列
}

Answer 12

我按照10楼的方法这样做了。还是只能添加一条。public partial class admin_Admin_SubmitReturnAdd : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        table_black.Visible = false;
    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        DataTable dt = (DataTable)GridView1.DataSource;
        if (dt == null)
        {
            dt = new DataTable();
            DataColumn bianhao1 = new DataColumn("bianhao", Type.GetType("System.String"));
            DataColumn mingcheng1 = new DataColumn("mingcheng", Type.GetType("System.String"));
            DataColumn yanse1 = new DataColumn("yanse", Type.GetType("System.String"));
            DataColumn chima1 = new DataColumn("chima", Type.GetType("System.String"));
            DataColumn shuliang1 = new DataColumn("shuliang", Type.GetType("System.String"));
            dt.Columns.Add(bianhao1);
            dt.Columns.Add(mingcheng1);
            dt.Columns.Add(yanse1);
            dt.Columns.Add(chima1);
            dt.Columns.Add(shuliang1);
        }
        
        DataRow _newRow = dt.NewRow();
        _newRow["bianhao"] = bianhao.Text.ToString();
        _newRow["mingcheng"] = bianhao.Text.ToString();
        _newRow["yanse"] = bianhao.Text.ToString();
        _newRow["chima"] = bianhao.Text.ToString();
        _newRow["shuliang"] = bianhao.Text.ToString();
        dt.Rows.Add(_newRow);
        GridView1.DataSource = dt;
        GridView1.DataBind();
        table_black.Visible = Visible;
    }
}

Answer 13

我上面说错了
每次都走DataTable dt = new DataTable(); 
你放到缓存里吧

Answer 14

protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            DataColumn bianhao1 = new DataColumn("bianhao", Type.GetType("System.String"));
            DataColumn mingcheng1 = new DataColumn("mingcheng", Type.GetType("System.String"));
            DataColumn yanse1 = new DataColumn("yanse", Type.GetType("System.String"));
            DataColumn chima1 = new DataColumn("chima", Type.GetType("System.String"));
            DataColumn shuliang1 = new DataColumn("shuliang", Type.GetType("System.String"));
            db.dt.Columns.Add(bianhao1);
            db.dt.Columns.Add(mingcheng1);
            db.dt.Columns.Add(yanse1);
            db.dt.Columns.Add(chima1);
            db.dt.Columns.Add(shuliang1);
        }
    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        DataRow _newRow = db.dt.NewRow();
        _newRow["bianhao"] = 2.ToString();
        _newRow["mingcheng"] = 3.ToString();
        _newRow["yanse"] = 6.ToString();
        _newRow["chima"] = 7.ToString();
        _newRow["shuliang"] = 8.ToString();
        db.dt.Rows.Add(_newRow);
        GridView1.DataSource = db.dt;
        GridView1.DataBind();
    }
这是代码，就是你原来的代码，稍加改动
你在项目里新加一个类，类里面写一句代码
public class db
{
    public static DataTable dt = new DataTable();
}
就可以实现了应该还有更好的方法

Answer 15

        public Form2()
        {
            InitializeComponent();
        }        private DataTable dt = new DataTable();
        private void Form2_Paint(object sender, PaintEventArgs e)
        {
           dt.Columns.Add(new DataColumn("列1"));
           dt.Columns.Add(new DataColumn("列2"));        }        private void button1_Click(object sender, EventArgs e)
        {
            DataRow dr = dt.NewRow();
            dt.Rows.Add(dr);            dt.Rows[dt.Rows.Count - 1]["列1"] = "111";
            dt.Rows[dt.Rows.Count - 1]["列2"] = "111";            dataGridView1.DataSource = dt;        }
    }

Answer 16

        private DataTable dt = new DataTable();
        private void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                dt.Columns.Add(new DataColumn("列1"));
                dt.Columns.Add(new DataColumn("列2"));
            }
        }
        private void button1_Click(object sender, EventArgs e)
        {
            DataRow dr = dt.NewRow();
            dt.Rows.Add(dr);            dt.Rows[dt.Rows.Count - 1]["列1"] = "111";
            dt.Rows[dt.Rows.Count - 1]["列2"] = "111";            dataGridView1.DataSource = dt;        }/*上面搞错了............我是在winform中测试的   妈的一直Server is too busy 不要我发了*/

Answer 17

修改代码如下：
protected void Button1_Click(object sender, EventArgs e) 
{ 
        DataTable dt = null;
        if(Session["db"] == null)
        {
          dt = new DataTable(); 
          DataColumn bianhao1 = new DataColumn("bianhao", Type.GetType("System.String")); 
          DataColumn mingcheng1 = new DataColumn("mingcheng", Type.GetType("System.String")); 
          DataColumn yanse1 = new DataColumn("yanse", Type.GetType("System.String")); 
          DataColumn chima1 = new DataColumn("chima", Type.GetType("System.String")); 
          DataColumn shuliang1 = new DataColumn("shuliang", Type.GetType("System.String")); 
          dt.Columns.Add(bianhao1); 
          dt.Columns.Add(mingcheng1); 
          dt.Columns.Add(yanse1); 
          dt.Columns.Add(chima1); 
          dt.Columns.Add(shuliang1);         } 
        else
        {
            dt = (DataTable)Session["db"];
        }
        
        DataRow _newRow = dt.NewRow(); 
        _newRow["bianhao"] = bianhao.Text.ToString(); 
        _newRow["mingcheng"] = bianhao.Text.ToString(); 
        _newRow["yanse"] = bianhao.Text.ToString(); 
        _newRow["chima"] = bianhao.Text.ToString(); 
        _newRow["shuliang"] = bianhao.Text.ToString(); 
        dt.Rows.Add(_newRow); 
        GridView1.DataSource = dt; 
        GridView1.DataBind(); 
        table_black.Visible = Visible; 
    }

Answer 18

貌似我的问题是一个购物车。楼上的加上Session["db"] = dt;就对了。现在问题暂时解决，我还要删除每行，，修改每行努力

Answer 19

可是session存储的数据很有限啊。晕啊。           

Answer 20

Cache 取网上找找，不是很难用！

Answer 21

你每次都一个button click都一个新的DataTable, 然后绑定到Grid上都是这个新的一行的DataTable, 你把DataTable放到外面去定义.

Answer 22

       public  DataTable dt = new DataTable();//把datatable放到外面就可以了啊 我用了可以添加
        private void comboBox1_SelectionChangeCommitted(object sender, EventArgs e)
        {            NewMethod(Convert.ToString(this.comboBox1.SelectedValue));
            this.dataGridView1.DataSource = dt;
        }        private void NewMethod(string enter)
        {
             
             if (dt.Columns.Count == 0)
             {
                 dt.Columns.Add("Id", typeof(System.Int32));
                 dt.Columns.Add("入库单号", typeof(System.String));
             }
            DataRow dr = dt.NewRow();
            if (textBox2.Text.Trim() == "")
            {
                dr[0] = 1;
                dr[1] = Convert.ToInt64(enter);
                textBox2.Text = "1";
                dt.Rows.Add(dr);
            }
            else
            {
                dr[0] = Convert.ToInt32(textBox2.Text) + 1;
                dr[1] = Convert.ToInt64(enter);
                textBox2.Text = Convert.ToString(Convert.ToInt32(textBox2.Text) + 1);
                dt.Rows.Add(dr);
            }
         
        }

Answer 23

得再加个 static 才行哦。public static DataTable dt = new DataTable()

Answer 24

DataTable dt = new DataTable();
  DataColumn bianhao1 = new DataColumn("bianhao", Type.GetType("System.String"));
  DataColumn mingcheng1 = new DataColumn("mingcheng", Type.GetType("System.String"));
  DataColumn yanse1 = new DataColumn("yanse", Type.GetType("System.String"));
  DataColumn chima1 = new DataColumn("chima", Type.GetType("System.String"));
  DataColumn shuliang1 = new DataColumn("shuliang", Type.GetType("System.String"));
  dt.Columns.Add(bianhao1);
  dt.Columns.Add(mingcheng1);
  dt.Columns.Add(yanse1);
  dt.Columns.Add(chima1);
  dt.Columns.Add(shuliang1);  
//把里面的DataTable dt = new DataTable();放到外面就行了,不然你每次点击按钮的话它都重新创建为0了，怎么可能一直加上去

Answer 25

protected void Page_Load(object sender, EventArgs e)
  {
    if (!IsPostBack)
            { 
               table_black.Visible = false;
             }
   }
 
将！ispostback加上试试

Answer 26

public partial class admin_Admin_SubmitReturnAdd : System.Web.UI.Page
{
dataTable dt=null;
  protected void Page_Load(object sender, EventArgs e)
  {
  table_black.Visible = false;
   if(viewstate["table"]!=null)
{
    dt=(DataTable)viewstate["table"];
}  }
  protected void Button1_Click(object sender, EventArgs e)
  {
    if (dt == null)
  {
  dt = new DataTable();
  DataColumn bianhao1 = new DataColumn("bianhao", Type.GetType("System.String"));
  DataColumn mingcheng1 = new DataColumn("mingcheng", Type.GetType("System.String"));
  DataColumn yanse1 = new DataColumn("yanse", Type.GetType("System.String"));
  DataColumn chima1 = new DataColumn("chima", Type.GetType("System.String"));
  DataColumn shuliang1 = new DataColumn("shuliang", Type.GetType("System.String"));
  dt.Columns.Add(bianhao1);
  dt.Columns.Add(mingcheng1);
  dt.Columns.Add(yanse1);
  dt.Columns.Add(chima1);
  dt.Columns.Add(shuliang1);
  }
    
  DataRow _newRow = dt.NewRow();
  _newRow["bianhao"] = bianhao.Text.ToString();
  _newRow["mingcheng"] = bianhao.Text.ToString();
  _newRow["yanse"] = bianhao.Text.ToString();
  _newRow["chima"] = bianhao.Text.ToString();
  _newRow["shuliang"] = bianhao.Text.ToString();
  dt.Rows.Add(_newRow);
  GridView1.DataSource = dt;
  GridView1.DataBind();
viewstate["table"]=dt;  table_black.Visible = Visible;
  }
}

Answer 27

楼主你好笨、因为是加在if (!IsPostBack)里的
再回来就是第一次点击了、

Answer 28

static DataTable dt=new DataTble();

Answer 29

帖子贴了3年没有一个正解，哎！
TableAdapter对象有一个clearbeforefill的属性，默认值是true.
设置为false后即可追加填充了。