在上面的链接中有一段代码

Dim idx As String = "-1,"
Dim idx_temp As String = ""
Dim pdr As DataRow = Nothing
Dim count As Integer = 0
Dim cs As String = "第一列,第二列,第三列"
For Each dr As DataRow In DataTables("表A").Select("", cs)
   
    Dim flag As Boolean = False
    If pdr IsNot Nothing Then
        For Each c As String In cs.split(",")
            If pdr(c) <> dr(c) Then
                flag = True
                Exit For
            End If
        Next
    End If
    If flag Then
        If count > 1 Then
            idx &= idx_temp
        End If
        count = 1
        idx_temp = ""
    Else
        count += 1
    End If
    idx_temp &= dr("_Identify") & ","
    pdr = dr
Next

If count > 1 Then
    idx &= idx_temp
End If

Tables("表A").filter = "_Identify in (" & idx.trim(",") & ")"

Dim pdr As DataRow = Nothing   ‘这个是什么意义

idx &= idx_temp   ’和  idx = idx_temp  等效吗？为什么多加一个&

count += 1   ’为什么多一个“+号”

If flag Then   ‘这个和  If flag = true Then  等效吧

1、Dim pdr As DataRow = Nothing   ‘这个是什么意义

定义一个变量，值为空，其它代码在赋值

2、idx &= idx_temp   ’和  idx = idx_temp  等效吗？为什么多加一个&

等同于：idx = idx & idx_temp 

3、count += 1   ’为什么多一个“+号”

等同于：count = count + 1

4、If flag Then   ‘这个和  If flag = true Then  等效吧

等效。flag本身就是逻辑型，不是True就是False