object reference not set to an instsnce of an object

[Mangesh Tomar]

I am inserting two records from txtxbox name as txtRegno and txtName when i run my prog i got error at con.open(); as object reference not set to an instsnce of an object need help here is the code using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; using System.Data.OleDb ; namespace studentManagementSystem1 { public partial class StudentDetails : Form { public OleDbCommand cmd; public OleDbConnection con; string connectionString, query; public StudentDetails() { InitializeComponent(); } private void StudentDetails_Load(object sender, EventArgs e) { // TODO: This line of code loads data into the 'studmanageDataSet.master' table. You can move, or remove it, as needed. this.masterTableAdapter.Fill(this.studmanageDataSet.master); connectionString =@"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=c:\studentManagementSystem1\studmanage.mdb"; } private void btnAdd_Click(object sender, EventArgs e) { int rows; query = "INSERT INTO master(RegNo,Name)VALUES(@RegNo,@Name)"; cmd = new OleDbCommand(query, con); cmd.Parameters.AddWithValue("@RegNo", txtRegNo.Text ); cmd.Parameters.AddWithValue("@Name", txtName.Text ); try { **con.Open();** rows = cmd.ExecuteNonQuery(); if (rows > 0) { MessageBox.Show("records inserted successfully"); } } catch (Exception ex) { MessageBox.Show(ex.Message); } finally { con.Close(); } } private void btnEdit_Click(object sender, EventArgs e) { } } }

[Abhishek Sur]

I cant see anywhere con is initialized... :(

try
{
con = new OleDbConnection(this.connectionString); // this is necessary to overcome from NullReferenceException...
con.Open();
rows = cmd.ExecuteNonQuery();

You need to initialize any object before you access any members . :) :rose:

Abhishek Sur **Don't forget to click "Good Answer" if you like this Solution.

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[Mangesh Tomar]

i try this but noe it shows the following error Execute Nonquery : Connection properly has not been initialized what to do?

[Not Active]

Mangesh Tomar wrote:

what to do?

RTFM!!

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only two letters away from being an asset

[Henry Minute]

For your use in future posts, this is not really a Database Problem. Your problems are not caused by the database. You should have posted it in the forum for the language you are using. C# I think in your case. :)

Henry Minute Do not read medical books! You could die of a misprint. - Mark Twain Girl: (staring) "Why do you need an icy cucumber?" “I want to report a fraud. The government is lying to us all.”

[Luc Pattyn]

traffic cop at work again? wouldn't it be easier to simply swap the two forum titles? :laugh:

Luc Pattyn

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I only read code that is properly indented, and rendered in a non-proportional font; hint: use PRE tags in forum messages

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[Abhishek Sur]

Inspect your connection object before you call con.open. Put a breakpoint and debug your application. :)

Abhishek Sur **Don't forget to click "Good Answer" if you like this Solution.

---

My Latest Articles-->** Microsoft Bing MAP using Javascript
CLR objects in SQL Server 2005
Uncommon C# Keywords/xml>

[Abhishek Sur]

Also put Initialization code above the creation of Command object

query = "INSERT INTO master(RegNo,Name)VALUES(@RegNo,@Name)";
con = new OleDbConnection(connectionstring);
cmd = new OleDbCommand(query, con);

cmd.Parameters.AddWithValue("@RegNo", txtRegNo.Text );
cmd.Parameters.AddWithValue("@Name", txtName.Text );

try
{
con.Open();
rows = cmd.ExecuteNonQuery();
if (rows > 0)
{
MessageBox.Show("records inserted successfully");
}
}

I think it will be working now. :rose:

Abhishek Sur **Don't forget to click "Good Answer" if you like this Solution.

---

My Latest Articles-->** Microsoft Bing MAP using Javascript
CLR objects in SQL Server 2005
Uncommon C# Keywords/xml>