// ----- C# -----

using System.Data.OleDb;
//...

//create the connection
OleDbConnection conn = new OleDbConnection(myconnstring);
try
{
    //open connection
    conn.Open();
    //create the command and call ExecuteScalar to get the single result
    string sql = "select mainphone from account where accountid = '" + myid + "'";
    OleDbCommand cmd = new OleDbCommand(sql, conn);
    string account = cmd.ExecuteScalar().ToString();

    //reuse the connection to get another value
    sql = "select mainphone from account where accountid = '" + myid + "'";
    cmd = new OleDbCommand(sql, conn);
    string phone = cmd.ExecuteScalar().ToString();

    MessageBox.Show(account + " - " + phone, "Result");
}
catch (Exception ex)
{
    MessageBox.Show("An error occurred: " + ex.Message, "Error");
}
finally
{
    conn.Dispose();
    conn = null;
}


' ----- VB.NET -----
Imports System.Data.OleDb
'...

'create the connection
Dim conn As New OleDbConnection(myconnstring)
Try
    'open connection
    conn.Open()
    'create the command and call ExecuteScalar to get the single result
    Dim sql As String = "select account from account where accountid = '" & myid & "'" 
    Dim cmd As New OleDbCommand(sql, conn)
    Dim account As String = cmd.ExecuteScalar().ToString()

    'reuse the connection to get another value
    sql = "select mainphone from account where accountid = '" & myid & "'"
    cmd = New OleDbCommand(sql, conn)
    Dim phone As String = cmd.ExecuteScalar().ToString()

    MessageBox.Show(account & " - " & phone, "Result")

Catch ex As Exception
    MessageBox.Show("An error occurred: " & ex.Message, "Error")
Finally
    conn.Dispose()
    conn = Nothing
End Try

// ----- C# -----
using System.Data.OleDb;
//...

//create the connection
OleDbConnection conn = new OleDbConnection(myconnstring);
try
{
    //open connection
    conn.Open();
    //create the command and call ExecuteReader to create the DataReader
    OleDbCommand cmd = new OleDbCommand("select account from account", conn);
    OleDbDataReader reader = cmd.ExecuteReader();

    //loop through the reader
    while(reader.Read())
    {
        listBox1.Items.Add(reader["account"].ToString());
    }
    reader.Close();
}
catch (Exception ex)
{
    MessageBox.Show("An error occurred: " + ex.Message, "Error");
}
finally
{
    conn.Dispose();
    conn = null;
}


' ----- VB.NET -----
Imports System.Data.OleDb
'...

'create the connection
Dim conn As New OleDbConnection(myconnstring)
Try
    'open connection
    conn.Open()
    'create the command and call ExecuteReader to create the DataReader
    Dim cmd As New OleDbCommand("select account from account", conn)
    Dim reader As OleDbDataReader = cmd.ExecuteReader()

    'loop through the reader
    While reader.Read()
        ListBox1.Items.Add(reader("account").ToString())
    End While
    reader.Close()

Catch ex As Exception
	MessageBox.Show("An error occurred: " & ex.Message, "Error")
Finally
	conn.Dispose()
	conn = Nothing
End Try

// ----- C# -----
using System.Data;
using System.Data.OleDb;
//...

//create the connection
OleDbConnection conn = new OleDbConnection(myconnstring);
try
{
    //open connection
    conn.Open();
    //create the DataAdapter. it will internally create a command object
    OleDbDataAdapter da = new OleDbDataAdapter("select Account from account", conn);

    //now create the DataSet and use the adapter to fill it
    DataSet ds = new DataSet();
    da.Fill(ds);

    //pull out the created DataTable to work with
    //our table is the first and only one in the tables collection
    DataTable table = ds.Tables[0];

    //iterate through the rows in the table's Rows collection
    foreach(DataRow row in table.Rows)
    {
        listBox1.Items.Add(row["account"].ToString());
    }

    //bind the table to a grid
    dataGrid1.DataSource = table;
}
catch (Exception ex)
{
    MessageBox.Show("An error occurred: " + ex.Message, "Error");
}
finally
{
    conn.Dispose();
    conn = null;
}


' ----- VB.NET -----
Imports System.Data
Imports System.Data.OleDb
'...

'create the connection
Dim conn As New OleDbConnection(myconnstring)
Try
    'open connection
    conn.Open()
    'create the DataAdapter. it will internally create a command object
    Dim da As New OleDbDataAdapter("select Account from account", conn)

    'now create the DataSet and use the adapter to fill it
    Dim ds As New DataSet()
    da.Fill(ds)

    'pull out the created DataTable to work with
    'our table is the first and only one in the tables collection
    Dim table As DataTable = ds.Tables(0)

    'iterate through the rows in the table's Rows collection
    Dim row As DataRow
    For Each row In table.Rows
        ListBox1.Items.Add(row("account").ToString())
    Next

    'bind the table to a grid
    DataGrid1.DataSource = table

Catch ex As Exception
    MessageBox.Show("An error occurred: " & ex.Message, "Error")
Finally
    conn.Dispose()
    conn = Nothing
End Try

// ----- C# -----

using System.Data.OleDb;
//...

//create the connection
OleDbConnection conn = new OleDbConnection(myconnstring);
try
{
    //open connection
    conn.Open();
    //create the command and call ExecuteNonQuery to execute the SQL statement in the database
    string sql = "update account set type = '.NET Rules' where accountid = '" + myid + "'";
    OleDbCommand cmd = new OleDbCommand(sql, conn);
    cmd.ExecuteNonQuery();
}
catch (Exception ex)
{
    MessageBox.Show("An error occurred: " + ex.Message, "Error");
}
finally
{
    conn.Dispose();
    conn = null;
}


' ----- VB.NET -----
Imports System.Data.OleDb
'...

'create the connection
Dim conn As New OleDbConnection(myconnstring)
Try
    'open connection
    conn.Open()
    'create the command and call ExecuteNonQuery to execute the SQL statement in the database
    Dim sql As String = "update account set type = '.NET Rules' where accountid = '" & myid & "'" 
    Dim cmd As New OleDbCommand(sql, conn)
    cmd.ExecuteNonQuery()

Catch ex As Exception
    MessageBox.Show("An error occurred: " & ex.Message, "Error")
Finally
    conn.Dispose()
    conn = Nothing
End Try

• GotDotNet.com - the official .NET community site.
• Code Project - This site is the greatest.
• C# Corner - Fairly good site. Lots of examples..
• And way too many VB.NET sites to mention