Query inside a Messagebox

[kizzieb]

Hello

I am trying to get the total of a query to show up inside a message box, an example of the coding is as shown below:

private void btnTotal_Click(object sender, EventArgs e)
{
conn.Open();
cmd.CommandText = "select sum(weight)FROM tbl_Fleet";
cmd.ExecuteNonQuery();
conn.Close();
MessageBox.Show(cmd.CommandText);
}
}

 

[JurkMonkey]

You want the result to show up? (Like the number 10 popping up in a dialog) or are you looking for the query text ("Select sum(weight)from...." to show up?

If it's the first option - you will want to populate a datatable and get the value from that.

http://msdn2.microsoft.com/en-us/library/aa325450(vs.71).aspx

In this case they are passing in a DataSet which returns tables. Change your select statement to

select sum(weight) as weight FROM tbl_Fleet

And then use the method shown in the article and you can get your value like this:

string weight = ds.Tables[0].Rows[0]["weight"].ToString();

Keep in mind this is very primitive and if anything were to go wrong you would know about it in a hurry (EXCEPTION!)

http://www.ubuntu.com/

 

[jmeckley]

since the query only returns a single value you an execute scalarquery and cast the result to an integer.

private void btnTotal_Click(object sender, EventArgs e)
{
   int count = 0;
   using(conn)
   {
      conn.Open();
      cmd.CommandText = "select sum(weight)FROM tbl_Fleet";
      count = (int)cmd.ExecuteScalar();
   }

   MessageBox.Show(count.ToString());
}

the using key word automatically closes/disposes the conn object

Jason Meckley
Programmer
Specialty Bakers, Inc.

 

[misterstick]

while [tt]using[/tt] is an absolute essential, what happens when the user clicks the button twice?

is it a good idea to dispose of objects you didn't create?



mr s. <

 

[JurkMonkey]

Putting the connection into a data access layer is the best idea. Wrap all queries in a try catch finally and dispose of your connection in the finally.

http://www.ubuntu.com/