I have error in this, but am unable to find that error any one find out that error

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The error is

Object reference not set to an instance of an object. 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.NullReferenceException: Object reference not set to an instance of an object. 
Source Error: Line 24: { Line 25: 
Line 26: sc = new SqlConnection(ConfigurationManager.ConnectionStrings["CompMSConnectionString1"].ConnectionString); Line 27: sc = new SqlConnection(@"Data Source=CIODEV03\\SQLEXPRESS;Initial Catalog=EmployeeDB;Integrated Security=True"); 
Line 28: sc.Open();

This is my code:

C#

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.Configuration;

public partial class Default2 : System.Web.UI.Page
{

	protected void Page_Load(object sender, EventArgs e)
	{

	}
	protected void btnsub_Click(object sender, EventArgs e)
	{
		if (Page.IsPostBack)
		{
			SqlConnection sc = null;
			SqlCommand cmd = null;
			try
			{

				sc = new SqlConnection(ConfigurationManager.ConnectionStrings["CompMSConnectionString1"].ConnectionString);
				sc = new SqlConnection(@"Data Source=CIODEV03\\SQLEXPRESS;Initial Catalog=EmployeeDB;Integrated Security=True");
				sc.Open();

				string query1 = String.Format(@"Insert Into student (rollno, fname, mname, lname) "+ " VALUES (@rollno, @fname, @mname, @lname)");
				cmd.Parameters.AddWithValue("@rollno",txtrollno.Text);
				cmd.Parameters.AddWithValue("@fname",txtfname.Text);
				cmd.Parameters.AddWithValue("@mname",txtmname.Text);
				cmd.Parameters.AddWithValue("@lname",txtlname.Text);
				cmd = new SqlCommand(query1, sc);
				cmd.ExecuteNonQuery();
				sc.Close();

				string query2 = String.Format(@"Insert Into studentmarks (rollno,marks) "+ " VALUES (@rollno, @marks)");
				cmd.Parameters.AddWithValue("@rollno",txtrol.Text);
				cmd.Parameters.AddWithValue("@marks", txtmarks.Text);
				cmd = new SqlCommand(query2, sc);
				cmd.ExecuteNonQuery();
			}
			finally // clean up
			{
				if(cmd != null)
					cmd.Dispose();
				if(sc != null)
					sc.Close();
			}
		}
	}
}

Posted 8-Mar-12 23:47pm

rockpune

Updated 9-Mar-12 0:02am

Dylan Morley

v4

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André Kraak 9-Mar-12 5:52am

Edited question:
Added pre tags
Formatted text/code

Dylan Morley 9-Mar-12 5:53am

What is the error?!

Dylan Morley 9-Mar-12 6:03am

Updated question - moved multiple comments into question details

André Kraak 9-Mar-12 5:53am

Please specify the error message you are getting.

If you wish to change your question use the Improve Question button.

OriginalGriff 9-Mar-12 5:53am

And what is the error?
What is happening that shouldn't, or not happing that should?

2 solutions

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E.F. Nijboer · Accepted Answer · 2012-03-08T23:59:00

Do you get a message or anything?
It might be you need to add a question mark to make the variable nullable.

SqlConnection? sc = null;

However, it would be better to assign the variable with the new instance instead of null. You can do that before the "try". But for even better code you should use using.

C#

using (SqlConnection sc = new SqlConnection(...) )
{
   ...
}

This way sc is always cleaned up automatically.

Good luck!

Dylan Morley · Accepted Answer · 2012-03-09T00:06:00

Make sure your connection string is correctly being retrieved from the configuration.

e.g.

C#

// Is this working? check your config - is 'CompMSConnectionString1' defined correctly?
string connectionString = ConfigurationManager.ConnectionStrings["CompMSConnectionString1"].ConnectionString);

then, you can follow E.F. Nijboer's answer to do something like...

C#

using (SqlConnection sc = new SqlConnection(connectionString ))
{
   sc.Open();
   // Do some SQL work...
}

I have error in this, but am unable to find that error any one find out that error

2 solutions

Solution 1

Solution 2

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