C# SQL สอบสอบถามท่านผู้รู้และใช้งานบ่อยๆเกี่ยวกับการเรียกใช้ database

<Serializable> _
Public Class Product
    Public Property ProductID As Integer
    Public Property ProductNameTH As String
    Public Property ProductNameUS As String
    '...
End Class

Public Class GlobalSessions
    Public Property ViewData As New List(Of Object)
    Public Shared ReadOnly Property Current() As GlobalSessions
        Get
            Dim gs = DirectCast(HttpContext.Current.Session("__GS__"), GlobalSessions)
            If gs Is Nothing Then
                gs = New GlobalSessions()
                HttpContext.Current.Session("__GS__") = gs
            End If
            Return gs
        End Get
    End Property

    Public Shared Sub ClearSession()
        GlobalSessions.Current.ViewData.Clear()
        GlobalSessions.Current.ViewData = Nothing
        HttpContext.Current.Session.Clear()
        HttpContext.Current.Session.Abandon()
    End Sub
End Class

'***** ทดสอบ *****
        'Generic List
        Dim lstProduct As New List(Of Product)() From {New Product With {.ProductID = 1, .ProductNameTH = "หอย"},
                                                       New Product With {.ProductID = 2, .ProductNameTH = "อร่อยดี"}
                                                      }

        'Set Values
        GlobalSessions.Current.ViewData = lstProduct.Cast(Of Object).ToList()

        'Get Values มันกลายเป็น 'Generic IEnumerable ได้อย่างไร?
        Dim lstProductGet = GlobalSessions.Current.ViewData.Cast(Of Product)()

Imports System.Collections.Generic
Imports System.Linq
Imports System.Reflection
Imports System.Linq.Expressions

Public Module IEnumerableHelper
    Sub New()
    End Sub

    Private orderBy_ As MethodInfo = GetType(Enumerable).GetMethods(BindingFlags.[Static] Or BindingFlags.[Public]) _
                                     .Where(Function(x) x.Name = "OrderBy" AndAlso x.GetParameters().Length = 2).First()

    <System.Runtime.CompilerServices.Extension()> _
    Public Function OrderBy(Of TSource)(source As IEnumerable(Of TSource), propertyName As String) As IEnumerable(Of TSource)
        Dim pi = GetType(TSource).GetProperty(propertyName, BindingFlags.[Public] Or BindingFlags.FlattenHierarchy Or BindingFlags.Instance)
        Dim selectorParam = Expression.Parameter(GetType(TSource), "keySelector")
        Dim sourceParam = Expression.Parameter(GetType(IEnumerable(Of TSource)), "source")
        Return Expression.Lambda(Of Func(Of IEnumerable(Of TSource), 
                                 IOrderedEnumerable(Of TSource)))(Expression.[Call](orderBy_.MakeGenericMethod(GetType(TSource), pi.PropertyType),
                                 sourceParam, Expression.Lambda(GetType(Func(Of ,)).MakeGenericType(GetType(TSource), pi.PropertyType),
                             Expression.[Property](selectorParam, pi), selectorParam)), sourceParam).Compile()(source)
    End Function

    <System.Runtime.CompilerServices.Extension()> _
    Public Function OrderBy(Of TSource)(source As IEnumerable(Of TSource), propertyName As String, ascending As Boolean) As IEnumerable(Of TSource)
        Return If(ascending, source.OrderBy(propertyName), source.OrderBy(propertyName).Reverse())
    End Function

End Module

#if COREFX
using IDbTransaction = System.Data.Common.DbTransaction;
using IDbConnection = System.Data.Common.DbConnection;
using DataException = System.InvalidOperationException;
#else
using System.Threading;
#endif