I have error when I am trying to connect my database

Question

Below is my code. Where I am passing connection string in Openconnection() function. But when Openconnection method is invoked, I am getting error.

 public class dbconn
    {
        string ConnetionString = null;
        string State = "";
        SqlConnection cnn;
    public string openconnection()
    {
        ConnetionString = @"Data Source=myservername;Initial Catalog=mydbname;Integrated Security=True";
        cnn = new SqlConnection(ConnetionString);
        try
        {
            cnn.Open();
            return State;
        }
        catch (Exception ex)
        {
             ...............
        }
    }

    public string closeconnection()
    {
        ConnetionString = @"Data Source=myservername;Initial Catalog=mydbname;Integrated Security=True";
        cnn = new SqlConnection(ConnetionString);
        try
        {
            cnn.Close();
            return State;
        }
        catch (Exception ex)
        {
           .........
        }
    }



}

when I am trying to call this class from my c# code part like

public dbconn dbcon;
private void btnsave_Click(object sender, EventArgs e)
{
  string State="";
  try
  {
    State= dbcon.openconnection();//*** Error in this line
    if (State!= "")
    {
      MessageBox.Show(State, "Lost Connection");
    }
 }
}

In *** part I've got error.

You're missing the `catch(){}` after your `try`. and what is the actual error? — Darren Wainwright, Dec 21 '16 at 15:35
Why don't you tell us _what_ error you get? I guess it's an exception, and the exception message probably tells you what went wrong. — René Vogt, Dec 21 '16 at 15:35
please read up on how to do a `try{}catch{}` properly and show us the error message — MethodMan, Dec 21 '16 at 15:35
I [advise against using such helper classes](http://stackoverflow.com/a/9707060/284240) that hold the sql-connection and manage opening/closing it, instead use the `using`-statement wherever you need to access the database. — Tim Schmelter, Dec 21 '16 at 15:36
I have catch and finally parts and my error is NullReferenceException was Unhandled An unhandled exception of type 'System.NullReferenceException' occurred in VeriTabanı.exe — ali durgun, Dec 21 '16 at 15:39
@FakeCaleb I tried it error has gone but still can't open connection it went to catch — ali durgun, Dec 21 '16 at 16:00

score 2 · Accepted Answer · answered Dec 21 '16 at 15:42

2

From your comment, I was right. You need to instantiate your dbconn object.

dbcon = new dbconn();

Overall though, I'd advise against using this sort of practice for SQL connections. Please look into using for whenever you're doing any sort of database access. (As Tim Schmelter has already stated in the comments)

answered Dec 21 '16 at 15:42

FakeCaleb

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I didn't get this error this time but my connection didn't opened – ali durgun Dec 21 '16 at 15:58
I can't help from 'didn't opened'. What error are you getting? What exactly is happening? – FakeCaleb Dec 21 '16 at 16:00
I don't get any error my program trying to open and it's going to catch then – ali durgun Dec 21 '16 at 16:01
I recommend printing the exception. `System.Diagnostics.Debug.WriteLine(ex.message);` in your catch and read whats happening, that will massively help you – FakeCaleb Dec 21 '16 at 16:02
I have ProcDurum = urunekle.proc(int.Parse(cbmüşteriseç.ToString()),txtürünadı.‌ToString(),dtcürüngi‌riştarihi.ToString()‌,float.Parse(txtkilo‌.ToString()), int.Parse(txtürünadeti.ToString()),txtkasatipi.ToString(),tx‌türünözelliği.ToStri‌ng(),txtplaka.ToStri‌ng()); in my code line and I have got catch expection in there – ali durgun Dec 21 '16 at 16:06
public urunekleproc urunekle=new urunekleproc(); i have that code line also – ali durgun Dec 21 '16 at 16:07
I think I understand what is wrong I have stored procedure and when I am trying to add record with using storeprocedureclass I have got error. @FakeCaleb – ali durgun Dec 21 '16 at 16:09
It seems that way (though due to the formatting and language, I'm struggling to comprehend the exact issue), as none of what you showed us above relates to what you are showing me here. I'm glad you figured out you're issue though. – FakeCaleb Dec 21 '16 at 16:11
1

Thanks again for your help :) – ali durgun Dec 21 '16 at 16:15

I have error when I am trying to connect my database

1 Answers1