How do I place data from the SQL Server database into a TextBox?

Question

I am missing something very simple. I have a form with 5 textBox and want to fill them with the data from the SQL Server database. Here is what I have so far:

As I debug this code line by line it returns to the calling block at the connection.open() line.

public void Get_Contact_Info()
{
    using (DataAccessClass.sql_Connection)
    {
        string SQL = "SELECT * FROM Customer_Contacts WHERE Contact_ID = @contact_Id";
        SqlCommand sqlCommand = new SqlCommand(SQL, DataAccessClass.sql_Connection);

        sqlCommand.Parameters.AddWithValue("@Contact_Id", contact_Id);
        sqlCommand.Parameters.AddWithValue("@Contact_Direct_Number", contact_Direct_NumberTextBox);
        sqlCommand.Parameters.AddWithValue("@Contact_Cell_Number", contact_Cell_NumberTextBox);
        sqlCommand.Parameters.AddWithValue("@Contact_Email", contact_EmailTextBox);
        sqlCommand.Parameters.AddWithValue("@Contact_Department", contact_DepartmentTextBox);

        DataAccessClass.sql_Connection.Open();

        using (SqlDataReader sqlDataReader = sqlCommand.ExecuteReader())
        {
            while (sqlDataReader.Read())
            {
                contact_Id = sqlDataReader["Contact_ID"].ToString();
            }
        DataAccessClass.sql_Connection.Close();
        }
    }
}

I have been doing a pretty good job of getting info from the user and saving it to the SQL Server DataTable but know I want to get some out so that I can edit the info.

Any help will be gratefully appreciated.

Here is my DataAccessClass

public static class DataAccessClass
    {
        static SqlConnection sqlConnection = new SqlConnection();

        public static SqlConnection sql_Connection
        {
            get { return sqlConnection; }
        }

        public static void OpenConnection()
        {
            string sqlString = Properties.Settings.Default.ConnectionString;
            sqlConnection.ConnectionString = sqlString;
            sqlConnection.Open();
        }

        public static void CloseConnection()
        {
            sqlConnection.Close();
        }
    }

Here is how I am calling Get_Contact_Info .

    private void Customer_Add_Contact_Form_Load(object sender, EventArgs e)
    {
        this.customer_ContactsBindingSource.AddNew();
        if (contact_Id == null)
        {
            contact_NameTextBox.Select();
        }
        else
        {
            Get_Contact_Info();
        }
    }

From a DataGridView I am selecting a row and passing customer_ID to the Customer_Add_Contact_Form so that I can edit the contact information. Here is the code for this step:

DataGridViewRow row = customer_ContactsDataGridView.CurrentCell.OwningRow;
string contact_ID = row.Cells[0].Value.ToString();
string customer_Ship_ID = null;

using (Form Customer_Add_Contact_Form = new Customer_Add_Contact_Form(customer_Ship_ID, contact_ID))

Answer 1

As discussed here it is better to let connection pooling manage the connections, so you can simplify your code to:

public void Get_Contact_Info()
{
    using (var connection = new SqlConnection(roperties.Settings.Default.ConnectionString))
    {
        connection.Open();

        var SQL = "SELECT * FROM Customer_Contacts WHERE Contact_ID = @contact_Id";

        var sqlCommand = new SqlCommand(SQL, connection);
        sqlCommand.Parameters.AddWithValue("@Contact_Id", contact_Id);

        using (var sqlDataReader = sqlCommand.ExecuteReader())
        {
            while (sqlDataReader.Read())
            {
                contact_Id = sqlDataReader["Contact_ID"].ToString();

                TextBoxName.Text = sqlDataReader["Contact_Name"].ToString();
                //etc ...
            }
        }
    }
}

I have removed unused parameters and created a new connection. Possibly you tried to open a connection using .Open() without initializing it with a connections string (is it roperties ?)