Object Reference Null in Connection Property ?

Question

0.00/5 (No votes)

See more:

C#

OleDbConnection cn;
public ExpireProduct()
{
    InitializeComponent();       
    cn = new OleDbConnection(@"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=D:\MIS SYSTEM\AniPharmic\AniPharmic\MedicalDb.accdb;Jet OLEDB:Database Password=****");          
}
try
{
    con.Open();
    str = "select *from DatabaseLogin where user_id='" + textBox2.Text + "'";
    com = new OleDbCommand(str, con);
    OleDbDataReader reader = com.ExecuteReader();
    while (reader.Read())
    {
       checkedListBox1.Items.Add(reader["stckdemge"]);
    }
}
catch (Exception ex)
{
    MessageBox.Show(" " + ex);
}

Error is In this Line 4 -

C#

con.Open();

Error is :- Cannot open Connection:System.NullReferenceException:Object Reference Not
set to an instance of an object.

Posted 28-Feb-13 15:43pm

kashifjaat

Updated 28-Feb-13 19:21pm

Orcun Iyigun

v2

Add a Solution

Comments

ZaneArellano 1-Mar-13 1:23am

where did that con came from? your connection is named cn

2 solutions

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Vani Kulkarni · Answer 1 · 2013-02-28T16:28:00

Solution 1

You have declared cn while declaring the connection object.
While using it, you have written con. Change it to cn and see if the error is still there.

Posted 28-Feb-13 16:28pm

Vani Kulkarni

Aarti Meswania · Answer 2 · 2013-02-28T17:36:00

because declared cn so you should write cn.open()
write this...

C#

try
           {
              cn.Open();
               str = "select *from DatabaseLogin where user_id='" + textBox2.Text + "'";
               com = new OleDbCommand(str, cn);
               OleDbDataReader reader = com.ExecuteReader();
               while (reader.Read())
               {
                   checkedListBox1.Items.Add(reader["stckdemge"]);
               }



           }
           catch (Exception ex)
           {
               MessageBox.Show(" " + ex);
           }

Happy Coding!
:)