……
dt1.Combine("型号",dt2,"型号") '将销售统计数据组合到进货统计数据
dt1.Combine("型号",dt3,"型号") '将退货统计数据组合到进货统计数据
Dim dt As DataTable = dt1.ConvetToDataTable
'Tables("窗口1_Table1").DataSource = dt1 '将统计结果绑定到Table
With dt.DataCols '用表达式列计算库存数据
.Add("库存_数量",Gettype(Integer), "IsNull([进货_数量],0) - ISNULL([销售_数量],0) - ISNULL([退货_数量],0)")
.Add("库存_金额",Gettype(Double), "[库存_数量] /[进货_数量] * [进货_金额]")
End With
Dim trv As WinForm.TreeView = e.Form.Controls("TreeView1")
trv.BuildTree(dt,"型号")