In addition to the answer above, if you have the misery of forgetting the Sitecore password then this will save you:

    UPDATE [aspnet_Membership] SET Password='qOvF8m8F2IcWMvfOBjJYHmfLABc='
    WHERE UserId IN (SELECT UserId FROM [aspnet_Users] WHERE UserName = 'sitecore\Admin')  

It resets the password to the classic 'b'.