Question

So i have the following string in c# that returns a mysql query.

string id = cmd.ExecuteScalar().ToString();

The problem is that if the indput to this string is not valid it crashes the app. This should not crash the app but show this:

MessageBox.Show("Your key (" + KeyNr + ") was invalid or not active. \nPlease check if it is the correct key or you need to buy another month.", "Login Error", MessageBoxButtons.OK, MessageBoxIcon.Error);

Tried with try and catch with no luck. can someone help?

some of my tries:

try
{
   string id = cmd.ExecuteScalar().ToString();
}
catch (Exception ex)
{
   MessageBox.Show("Your key (" + KeyNr + ") was invalid or not active. \nPlease check if it is the correct key or you need to buy another month.", "Login Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
}

and

try
{
   string id = cmd.ExecuteScalar().ToString();
}
catch (catch (MySqlException))
{
   MessageBox.Show("Your key (" + KeyNr + ") was invalid or not active. \nPlease check if it is the correct key or you need to buy another month.", "Login Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
}

all gives me:

Error   2   The name 'id' does not exist in the current context

Answer 1

Try this piece of code:

string id = string.Empty;

try
{
   id = cmd.ExecuteScalar().ToString();
}
catch(Exception ex)
{
    MessageBox.Show("Your key (" + KeyNr + ") was invalid or not active. \nPlease check if it is the correct key or you need to buy another month.", "Login Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
}

You can even catch it to more specific Exception instead of having generic Exception.