表B的DataColChanged事件 中设置如下代码：

If e.DataCol.Name = "调度单号" Then 

if e.datarow.isnull("调度单号") then

e.DataRow("商品车") = nothing

else

Dim g As New GroupTableBuilder("统计表1", DataTables("表A"))
g.Groups.AddDef("商品车")
g.Totals.AddDef("台数")

g.filter = "调度单号=\'" & e.newvalue & "\'"

dim dt as datatable = g.Build(true)

dim s as string = ""

for each dr as datarow in dt.datarows

s = s & "," & dr("商品车") & dr("台数") & "台"

next
    e.DataRow("商品车") = s.trim(",")

end if
End If