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我使用以下代码删除和编辑gridview中的一些值，但是当我单击删除时，它显示错误：

Object reference not set to an instance of an object. in line 48 i.e. con.open();

请帮我解决它。当我单击编辑并在显示的 txtboxes 中插入值然后单击更新时，它显示另一个错误：

Specified argument was out of the range of valid values. in the line 74 of my code i.e.
   EmailID = (TextBox)GridView1.Rows[e.RowIndex].Cells[7].FindControl("EmailID");

我使用的代码是-

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data.SqlClient;
using System.Data;

public partial class Admin_viewSalesmanDetails : System.Web.UI.Page
{
    SqlConnection con;
    String strConnection = "Data Source=HP\\SQLEXPRESS;database=MK;Integrated Security=true";
    SqlCommand cmd;
    protected void Page_Load(object sender, EventArgs e)
    {

        if (!IsPostBack)
        {
            BindGrid();
        }


    }

    private void BindGrid()
    {
          using (SqlConnection con = new SqlConnection(strConnection))
        {
            using (SqlCommand cmd = new SqlCommand())
            {

                cmd.CommandText = "select * from salesman_details";
                cmd.Connection = con;


                SqlDataSource1.DataBind();
                GridView1.DataSource = SqlDataSource1;
                GridView1.DataBind();

            }
        }
    }
    protected void GridView1_RowDeleting(object sender, GridViewDeleteEventArgs e)
    {
        Label EmpID = new Label();
        EmpID = (Label)GridView1.Rows[e.RowIndex].Cells[2].FindControl("EmpID");
        cmd = new SqlCommand("delete from salesman_setails where EmpID=" + EmpID.Text + "", con);
        con.Open();
        int k = cmd.ExecuteNonQuery();
        con.Close();
        if (k == 1)
        {
            Response.Write("<script>alert('Employee Deleted Successfully')</script>");
            BindGrid();
        }
        else
        {
            Response.Write("<script>alert('Error Occured While Deleting')</script>");
            BindGrid();
        }
    }
    protected void GridView1_RowEditing(object sender, GridViewEditEventArgs e)
    {
        GridView1.EditIndex = e.NewEditIndex;
        BindGrid();

    }
    protected void GridView1_RowUpdating(object sender, GridViewUpdateEventArgs e)
    {
        Label EmpID = new Label();
        TextBox PhnNo = new TextBox();
        TextBox EmailID = new TextBox();
        EmpID = (Label)GridView1.Rows[e.RowIndex].Cells[2].FindControl("EmpID");
        PhnNo = (TextBox)GridView1.Rows[e.RowIndex].Cells[5].FindControl("PhnNo");
        EmailID = (TextBox)GridView1.Rows[e.RowIndex].Cells[7].FindControl("EmailID");
        cmd = new SqlCommand("update  salesman_details set PhnNo='" + PhnNo.Text + "', EmailID='" + EmailID.Text + "' where EmpID=" + EmpID.Text + "", con);
        con.Open();
        int k = cmd.ExecuteNonQuery();
        con.Close();
        if (k == 1)
        {
            Response.Write("<script>alert('Employee Updated Successfully')</script>");
            GridView1.EditIndex = -1;
            BindGrid();

        }
        else
        {
            Response.Write("<script>alert('Error Occured While Updating')</script>");
            BindGrid();
        }

    }

    protected void GridView1_RowCancelingEdit(object sender, GridViewCancelEditEventArgs e)
    {
        GridView1.EditIndex = -1;
        BindGrid();
    }


    protected void GridView1_PageIndexChanging(object sender, GridViewPageEventArgs e)
    {
        GridView1.PageIndex = e.NewPageIndex;
        BindGrid();
    }
}
4

2 回答 2

2

在你GridView1_RowDeleting和GridView1_RowUpdating你还没有初始化你con和你试图打开它。

您可以在声明时或在事件中使用期间实例化连接。

public partial class Admin_viewSalesmanDetails : System.Web.UI.Page
{
      String strConnection = "Data Source=HP\\SQLEXPRESS;database=MK;Integrated Security=true";
      SqlConnection con = new SqlConnection(strConnection);

或者更好的方法是在事件的using语句中实例化它。例如。

protected void GridView1_RowDeleting(object sender, GridViewDeleteEventArgs e)
{
    Label EmpID = new Label();
    EmpID = (Label)GridView1.Rows[e.RowIndex].Cells[2].FindControl("EmpID");
    cmd = new SqlCommand("delete from salesman_setails where EmpID=" + EmpID.Text + "", con);
    using( con = new SqlConnection(strConnection))
    {
        cmd.Connection = con; //here
        con.Open();
        int k = cmd.ExecuteNonQuery();
        con.Close();
        if (k == 1)
        {
            Response.Write("<script>alert('Employee Deleted Successfully')</script>");
            BindGrid();
        }
        else
        {
            Response.Write("<script>alert('Error Occured While Deleting')</script>");
            BindGrid();
        }
    }
}

using语句将确保Dispose在连接上调用它（这也会关闭连接），即使发生一些异常。

于 2013-05-21T10:57:32.670 回答
0

PostBacks私有字段在您使用的事件 ( GridView1_RowDeleting)之间丢失，SqlConnection而没有先初始化它。

添加

con = new SqlConnection(strConnection);

前con.Open();

于 2013-05-21T10:57:13.273 回答