string sqlServer = Properties.Settings.Default.sqlServer;
            string sqlPort = Properties.Settings.Default.sqlPort;
            string sqlUsername = Properties.Settings.Default.sqlUsername;
            string sqlPassword = Properties.Settings.Default.sqlPassword;
            string sqlDatabase = Properties.Settings.Default.sqlDatabase;

            string sqlConnectionString = "Server=" + sqlServer + "," + sqlPort + ";";
            sqlConnectionString += "User ID=" + sqlUsername + ";";
            sqlConnectionString += "Password=" + sqlPassword + ";";
            sqlConnectionString += "Database=" + sqlDatabase;

            SqlConnection sqlConnection = new SqlConnection();

            try
            {
                sqlConnection.ConnectionString = sqlConnectionString;
                sqlConnection.Open();
            }
            catch (Exception Ex)
            {
                if (sqlConnection != null)
                    sqlConnection.Dispose();

                string sqlErrorMessage = "Ett fel inträffade vid anslutningsförsök.";
                sqlErrorMessage += Environment.NewLine;
                sqlErrorMessage += Environment.NewLine;
                sqlErrorMessage += Ex.Message;

                MessageBox.Show(sqlErrorMessage, "Anslutningsfel", MessageBoxButtons.OK, MessageBoxIcon.Error);
                return;
            }

            string sqlQuery = "SELECT * FROM persons";
            SqlDataAdapter sqlDataAdapter = new SqlDataAdapter(sqlQuery, sqlConnection);
            DataTable resultat = new DataTable();
            sqlDataAdapter.Fill(resultat);

            foreach (DataRow row in resultat.Rows)
            {
                MessageBox.Show(row["firstname"].ToString());
            }
            sqlDataAdapter.Dispose();
            sqlConnection.Close();
            sqlConnection.Dispose();