private DataTable GetCats()
        {
            DataTable dt = new DataTable();
            MySqlConnectionStringBuilder mysqlCSB;
            mysqlCSB = new MySqlConnectionStringBuilder();
            mysqlCSB.Server = textBox1.Text;
            mysqlCSB.Database = textBox2.Text;
            mysqlCSB.UserID = textBox3.Text;
            mysqlCSB.Password = textBox4.Text;
            string queryString = @"SELECT blablabla FROM blablabla WHERE blabla IN (SELECT blabla FROM blablabla WHERE blablabla='blablabla')";
            using (MySqlConnection con = new MySqlConnection())
            {
                con.ConnectionString = mysqlCSB.ConnectionString;
                MySqlCommand com = new MySqlCommand(queryString, con);
                try
                {
                    con.Open();
                    using (MySqlDataReader dr = com.ExecuteReader())
                    {
                        if (dr.HasRows)
                        {
                            dt.Load(dr);
                        }
                    }
                }
                catch (Exception ex)
                {
                    MessageBox.Show(ex.Message);
                }
            }
            return dt;
        }  public static void SQLSendData(string ConnectionString, string CommandString)
{
    using (MySqlConnection connection = new MySqlConnection(ConnectionString))
    {
        try
        {
            MySqlCommand command = new MySqlCommand(CommandString, connection);
            command.Connection = connection;
            connection.Open();
            rowsAffected = command.ExecuteNonQuery();
        }
        catch (SqlException e)
        {
            MessageBox.Show(e.Message);
        }
        finally
        {
            connection.Close();
        }
    }
}SQLSendData("ConnectionString", "UPDATE blablalbalba");