student management system

Both DataSource and DataSourceID are defined on 'GridView1'.  Remove one definition.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.InvalidOperationException: Both DataSource and DataSourceID are defined on 'GridView1'.  Remove one definition.

Source Error:

Line 26: 
Line 27:             GridView1.DataSource = dt;
Line 28:             GridView1.DataBind();
Line 29:         }
Line 30:     }

Source File: c:\Users\Ujwal S shetty\OneDrive\Mobile =doc,pic,videos\Desktop\Mini Project\studentmanagement\studentmanagement\ManageStudent.aspx.cs    Line: 28

Stack Trace: using System;

using System.Data;

using System.Data.OleDb;

using System.Configuration;

public partial class Pages_ManageStudent : System.Web.UI.Page

{

string connStr = ConfigurationManager.ConnectionStrings["AccessConn"].ConnectionString;

protected void Page_Load(object sender, EventArgs e)

{

if (!IsPostBack)

{

BindGrid();

}

}

void BindGrid()

{

using (OleDbConnection conn = new OleDbConnection(connStr))

{

string sql = "SELECT * FROM Students";

OleDbDataAdapter da = new OleDbDataAdapter(sql, conn);

DataTable dt = new DataTable();

da.Fill(dt);

GridView1.DataSource = dt;

GridView1.DataBind();

}

}

protected void GridView1_RowEditing(object sender, System.Web.UI.WebControls.GridViewEditEventArgs e)

{

GridView1.EditIndex = e.NewEditIndex;

BindGrid();

}

protected void GridView1_RowCancelingEdit(object sender, System.Web.UI.WebControls.GridViewCancelEditEventArgs e)

{

GridView1.EditIndex = -1;

BindGrid();

}

protected void GridView1_RowUpdating(object sender, System.Web.UI.WebControls.GridViewUpdateEventArgs e)

{

int id = Convert.ToInt32(GridView1.DataKeys[e.RowIndex].Value);

string name = ((System.Web.UI.WebControls.TextBox)GridView1.Rows[e.RowIndex].Cells[1].Controls[0]).Text;

string roll = ((System.Web.UI.WebControls.TextBox)GridView1.Rows[e.RowIndex].Cells[2].Controls[0]).Text;

string sclass = ((System.Web.UI.WebControls.TextBox)GridView1.Rows[e.RowIndex].Cells[3].Controls[0]).Text;

string contact = ((System.Web.UI.WebControls.TextBox)GridView1.Rows[e.RowIndex].Cells[4].Controls[0]).Text;

string email = ((System.Web.UI.WebControls.TextBox)GridView1.Rows[e.RowIndex].Cells[5].Controls[0]).Text;

string courseId = ((System.Web.UI.WebControls.TextBox)GridView1.Rows[e.RowIndex].Cells[6].Controls[0]).Text;

using (OleDbConnection conn = new OleDbConnection(connStr))

{

string sql = "UPDATE Students SET Name=?, RollNo=?, ClassName=?, Contact=?, Email=?, CourseId=? WHERE StudentId=?";

OleDbCommand cmd = new OleDbCommand(sql, conn);

cmd.Parameters.AddWithValue("?", name);

cmd.Parameters.AddWithValue("?", roll);

cmd.Parameters.AddWithValue("?", sclass);

cmd.Parameters.AddWithValue("?", contact);

cmd.Parameters.AddWithValue("?", email);

cmd.Parameters.AddWithValue("?", courseId);

cmd.Parameters.AddWithValue("?", id);

conn.Open();

cmd.ExecuteNonQuery();

}

GridView1.EditIndex = -1;

lblMsg.Text = "Student updated successfully!";

BindGrid();

}

protected void GridView1_RowDeleting(object sender, System.Web.UI.WebControls.GridViewDeleteEventArgs e)

{

int id = Convert.ToInt32(GridView1.DataKeys[e.RowIndex].Value);

using (OleDbConnection conn = new OleDbConnection(connStr))

{

string sql = "DELETE FROM Students WHERE StudentId=?";

OleDbCommand cmd = new OleDbCommand(sql, conn);

cmd.Parameters.AddWithValue("?", id);

conn.Open();

cmd.ExecuteNonQuery();

}

lblMsg.Text = "Student deleted successfully!";

BindGrid();

}

protected void btnHome_Click(object sender, EventArgs e)

{

Response.Redirect("Home.aspx");

}

}

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="ManageStudent.aspx.cs" Inherits="Pages_ManageStudent" %>