MSG BOX prob in c#

Question

I'm a Beginner in c# so It's not encouraging to me see you voting down on my basic question...

This is a button to show in a message Box the result of my select from my BD.

I get errors : Argument '2': cannot convert from 'object' to 'string', Argument '3': cannot convert from 'object' to 'System.Windows.Forms.MessageBoxButtons'

Thank's for helping me!

  private void Button1Click(object sender, EventArgs e)
    {
        thisConnection.Open();
        SqlCommand thisCommand = thisConnection.CreateCommand();
        thisCommand.CommandText = "Select id_Client,numéro_Teléphone from Clients";

        SqlDataReader thisreader = thisCommand.ExecuteReader();

        while (thisreader.Read())
        {
            MessageBox.Show(thisreader["id_Client"],thisreader["numéro_Teléphone"]);
        }
        thisreader.Close();
        thisConnection.Close();



    }

Answer 1

Couple things I would add here.

I don't think the call

thisreader["id_Client"].ToString()

is DBNull safe, meaning if the actual value back from the database is NULL this might cause a problem.

Secondly, your connection to the database server will not be closed until a user has clicked through all of the MessageBoxes. That might not be expected behavior. I almost always use a DataTable and a SqlDataAdapter to fill it, that way I know I have all my data back from the server and my connection has been closed so I am not using up extra resources on the server.

Also another things, since you are new to C# your

thisreader.Close();
thisConnection.Close();

might not get executed, you need to either do a

try / catch / finally

or a

using()

statement. Just giving you some best practices stuff to think about.

Answer 2

Try,

MessageBox.Show(thisreader["id_Client"].ToString() + " " +  
       thisreader["numéro_Teléphone"].ToString());

Read MSDN doc for more details.

EDIT:

Use System.Text.StringBuilder to append strings.

System.Text.StringBuilder sb=new System.Text.StringBuilder();

while (thisreader.Read())
 {
    sb.Append("\n" +  thisreader["id_Client"].ToString() + " " +  
           thisreader["numéro_Teléphone"].ToString());   

   //or
   //sb.Append(string.Format("\n{0} {1}",thisreader["id_Client"],thisreader["numéro_Teléphone"]));      
 }
 MessageBox.Show(sb.ToString());