อยากทราบความหมายของโค๊ดนี้ครับว่ามันทำหน้าที่อะไร อยากทราบความหมายครับ

Private Function autoGenOneKeyID(ByVal cum As String, ByVal t_Name As String) As Long
        Dim sqlTmp As String = ""
        Dim LastID As Int64 = 0
        Dim NextID As Int64 = 1
        sqlTmp = "SELECT " + cum + " FROM " + t_Name
        sqlTmp += " ORDER BY " + cum + " DESC LIMIT 1"
        Try
            Dim DS As DataSet = ReadDbMysql(sqlTmp, "Obj")
            LastID = Convert.ToInt64(DS.Tables("Obj").Rows(0).Item(cum))
            LastID += 1
            NextID = LastID
        Catch
        End Try
        Return NextID
    End Function