Error in C#

[Execute0426]

Hi guys can you please help me in my code? 

Here is my code:

 db.Open();
            MySqlCommand SQL1 = new MySqlCommand("Insert Into tblStudent(`IDNo`, `Grade`, `Section`, `LastName`, `FirstName`, `MiddleName`, `Gender`, 					`Address`, `ContactNo`, `Status`) VALUES ('" + getID() + "', '" + comboBox1.Text + "', '" + comboBox2.Text + "', '" + comboBox3.Text + "', '" + 			textBox1.Text + "', '" + textBox2.Text + "', '" + textBox3.Text + "', '" + comboBox4.Text + "', '" + textBox4.Text + "', '" + textBox5.Text + "', 			  '1');", db);
            SQL1.ExecuteNonQuery();
            db.Close();
            MessageBox.Show("One Record has been Added.", "Success", MessageBoxButtons.OK, MessageBoxIcon.Asterisk);
        

it always says that "The connection is already open". please respond thnk you.

[vorticalbox]

means you probably have db.open(); somewhere else in your code.

[Execute0426]

2 hours ago, vorticalbox said:

means you probably have db.open(); somewhere else in your code.

i remove that db.open(); and nothing happened. the error is the same.

 

[madknight3]

It's usually good practice to dispose of any IDisposable objects. In this case, your MySqlConnection and MySqlCommand classes both implement IDisposable.

 

You can either do this manually by calling the Dispose() method, or you can wrap them in using statements like so which automatically calls it for you.

using (var connection = new MySqlConnection(connectionString))
{
    connection.Open();
    
    var query = "... sql query here ...";
    using (var command = new MySqlCommand(query, connection))
    {
        // Add parameters if necessary. 
        // They add protection against Sql Injection (https://en.wikipedia.org/wiki/SQL_injection).
        // Example)
        // command.Parameters.AddWithValue("@param", value);

        command.ExecuteNonQuery();
    }
}

// Forgive any errors with using the MySql classes. I've done this stuff with Sql Server
// but not MySql so I'm only going off a quick google search. If the MySql classes work in the same way, 
// disposing should clean up all the connections for you so it's easier to avoid errors like you're getting.