php - 用 sql 表绘制谷歌图

Question

我使用 Google graph 在 sql 表中绘制带有变量的图，下面是我的代码，如您所见，它用表的最后一行绘制了一个图，如何绘制最后一行 3？我知道我应该使用DESC LIMIT 3但如何使用？

<?php
    $result = mysql_query("SELECT * FROM result ORDER BY id DESC LIMIT 1");
    $value=array();
    while($r = mysql_fetch_assoc($result)) {
        $year=$r['year'];
        $sales=$r['sales'];
        $expenses=$r['expenses'];
        $val="[".$year.",".$sales.",".$expenses."]";
        array_push($value,$val );
    }
    $final_value = implode(",", $value);
?>

function drawChart() {
    var data = google.visualization.arrayToDataTable([
        <?php echo $final_value?>
    ]);

    var options = {
        title: 'Company Performance'
    };

    var chart = new google.visualization.LineChart(document.getElementById('chart_div'));
    chart.draw(data, options);
}

Answer 1

这是真的吗？你已经知道答案了！

SELECT * FROM result ORDER BY id DESC LIMIT 1

将其更改为

SELECT * FROM result ORDER BY id DESC LIMIT 3

？？？