如何在主窗体使用向上和向下移动子窗体中每一条记录

function 移动(frm as form,str as string)

'示例：call 移动(me.员工子窗体.form,"向下")

select case str

    case "向下"

        if frm.newRecord=true then exit function

        frm.seltop=frm.seltop+1

    case "向上"

        if frm.seltop=1 then exit function

        frm.seltop=frm.seltop-1

end select

end function