a.vb

dim yearfirst as integer = 10000
dim yearlast as integer = -1

'先把首年跟最後一年取出來
for each activity in liactivity
    if activity.year > yearlast then
        yearlast = activity.year
    end

    if activity.year < yearfirst then
        yearfirst = activity.year
    end
next

'再依年去一個一個取出 liactivity 的內容
for i = yearlast to yearfirst step -1
    dim newrow as data.datarow = dt.newrow

    for each activity in liactivity
        if activity.year = i then
            newrow("years) = i

            if activity.animalid = 乳牛 then
                newrow("cow") = activity.animalamount
            elseif activity.animalid = 豬 then
                newrow("pig") = activity.animalamount            
            end if
        end if
    next activity

    dt.rows.add(newrow)
next i