主题：查询

If DataTables("订单主表").DataRows.Count = 0 Then '如果订单表没有数据
    DataTables("订单").LoadFilter = "订单编号 Is Null" '不加载订单明细
Else
    Dim ids As String
    For Each dr As DataRow In DataTables("订单主表").DataRows
        ids = ids & ",'" & dr("订单编号") & "'"
    Next
    ids= ids.Trim(",")
    DataTables("订单").LoadFilter = "订单编号 In (" & ids.trim(",") & ")"
End If
DataTables("订单").Load()