试试这样
Dim txt As String = e.Form.Controls("txtMingcheng").Text
Dim tbl As DataTable = Tables("窗口产品销售_tblChanpin").DataTable
If txt = "" Then
tbl.LoadFilter = ""
Else
txt = "'%" & txt & "%'"
tbl.LoadFilter = "product_name Like " & txt
End If
Tables("窗口产品销售_tblChanpin").Filter = ""
tbl.Loadtop = 1000 '假定每页1000行
tbl.Loadpage = 0
tbl.Load()