上图左侧为目录树,左下角为刷新该目录树,目录树的Datatable有1500行数据左右,为sql服务器数据源,刷新目录树的代码执行效率非常低,刷新一次要等很长时间,如何才能优化下面这段代码,缩短执行时间?
\'2.目录树显示统计数据
For Each nd As WinForm.TreeNode In trv.AllNodes
Dim kg As new String(".",24- nd.Name.Length*2)
Dim sum As Integer
Select nd.Level
Case 0
If nd.Name <> "全市数据" Then
sum = DataTables("特困人员表").SQLCompute("count([_Identify])","县市区 = \'" & nd.Name & "\'")
Else
sum= DataTables("特困人员表").SQLCompute("count([_Identify])","[_Identify] is not null")
End If
kg = kg & "......"
Case 1
sum = DataTables("特困人员表").SQLCompute("count([_Identify])","县市区 = \'" & nd.DataRow("县市区") & "\' and 乡镇 = \'" & nd.DataRow("乡镇") & "\'")
kg = kg & "..."
Case 2
sum = DataTables("特困人员表").SQLCompute("count([_Identify])","县市区 = \'" & nd.DataRow("县市区") & "\' and 乡镇 = \'" & nd.DataRow("乡镇") & "\' and 村居 = \'" & nd.DataRow("村居") & "\'")
End Select
If sum > 0 Then
nd.Text = nd.Name & kg & sum & "人"
End If
Next