Question

I want to be able to display balance to label and my code is not working. This is code I got so far:

SqlDataReader readdata;

{
    sqlCommandbalance.Connection.Open();
    sqlCommandbalance.Parameters["@accountID"].Value = show.accoundID;
    readdata = sqlCommandbalance.ExecuteReader();
    string balanceDB = null;
    while (readdata.Read())
    {
        balanceDB = readdata["balance"].ToString();
    }
    sqlCommandbalance.Connection.Close();
    balanceShow.Text += " " + balanceDB.ToString();
}

On this line – balanceShow.Text += " " + balanceDB.ToString(); got a error saying Object reference not set to an instance of an object.

Answer 1

You’re calling balanceDB.ToString(), when balanceDB will be null if the data reader contains no rows.

Note that balanceDB.ToString() is redundant, since balanceDB is already a string. Just take out the ToString call.

You could also initialize balanceDB as

string balanceDB = "";