Database

ProcessStartInfo psi = new ProcessStartInfo();
psi.FileName = "path/to/file.udl";
psi.UseShellExecute = true;
Process.Start(psi);

using System;
using System.ComponentModel;
using System.Runtime.InteropServices;
using System.Windows.Forms;
using ADODB;
using MSDASC;
 
public sealed class DataLinkDialog : CommonDialog
{
    private string _connectionString;
    
    /// <summary>
    /// Constructor
    /// </summary>
    /// <param name="connectionString">The initial connection string</param>
    public DataLinkDialog(string connectionString)
    {
        _connectionString = connectionString;
    }
    
    /// <summary>
    /// Constructor
    /// </summary>
    public DataLinkDialog()
    {
        _connectionString = string.Empty;
    }
    
    /// <summary>
    /// Gets or sets the connection string
    /// </summary>
    public string ConnectionString
    {
        get { return _connectionString; }
        set { _connectionString = value; }
    }
    
    /// <summary>
    /// Resets the properties of the dialog box
    /// to their default values.
    /// </summary>
    public override void Reset()
    {
        _connectionString = string.Empty;
    }
    
    /// <summary>
    /// Displays the dialog box.
    /// </summary>
    /// <param name="hwndOwner">
    /// A value that represents the window handle of the 
    /// owner window for the common dialog box.
    /// </param>
    /// <returns>
    /// true if the dialog box was successfully run;
    /// otherwise, false.
    /// </returns>
    protected override bool RunDialog(IntPtr hwndOwner)
    {
        DataLinks dl = new DataLinksClass();
        try
        {
            if (null == _connectionString || 0 == _connectionString.Length)
            {
                object ret = dl.PromptNew();
                if (null == ret)
                {
                    return false;
                }
                else
                {
                    _connectionString = ((ADODB._Connection)ret).ConnectionString;
                    Marshal.ReleaseComObject(ret);
                    return true;
                }
            }
            else
            {
                Connection cn = new ConnectionClass();
                object ocn = cn;
                try
                {
                    cn.ConnectionString = _connectionString;
                    if (dl.PromptEdit(ref ocn))
                    {
                        _connectionString = cn.ConnectionString;
                        return true;
                    }
                    else
                    {
                        return false;
                    }
                }
                finally
                {
                    Marshal.ReleaseComObject(cn);
                }
            }
        }
        finally
        {
            Marshal.ReleaseComObject(dl);
        }
    }
}

convert a date to a string
    to_char(some_date_field,'dmy')

convert a string to a date
    to_date(some_char_field,'dmy')

"In the confrontation between the stream and the rock, the stream always wins - not through strength but perseverance." (H. Jackson Brown)

Enumerators in .NET: See how to customise foreach loops with C#

SELECT lastname
FROM Employees
where lastname like '[a-d]*'