主题：外部数据源SQL查询的速度问题

 代码如下，有问题吗？数据源里有6张表，现在有8500行，每一行不知道在具体哪张表上，要分别去每张表查。查询8500行用了半个小时。。。。。。。。这个速度太慢了吧。         

            Dim cmd As New SQLCommand
            Dim dt As DataTable
            cmd.C
            For Each dtn As String In Connections("泉州").GetTableNames
                cmd.CommandText = "SELECT * From {" & dtn & "} where [PVLAN] = " & e.DataRow("板/PVLAN") & " And [CVLAN] = " & e.DataRow("端口/CVLAN")
                dt = cmd.ExecuteReader
                If dt.DataRows.Count > 0 Then
                    e.DataRow("LOID") = dt.DataRows(0)("LOID")
                    e.DataRow("PON口") = dt.DataRows(0)("PON口")
                    e.DataRow("ONUID") = dt.DataRows(0)("ONUID")
                    exit for
                Else
                    e.DataRow("LOID") = Nothing
                    e.DataRow("PON口") = Nothing
                    e.DataRow("ONUID") = Nothing
                End If
            Next