主题：[求助]如果没有查询到，弹出提示框

Dim txt As String = e.Form.Controls("TextBox2").Text
Dim tbl As Table = Tables("病人表")
If txt = "" Then
    tbl.Filter = ""
Else
    txt = "'%" & txt & "%'"
    tbl.Filter = "姓名  Like " & txt         '模糊查询
End If

如果没有查询到，弹出提示框 

如何接着这段代码往下面写