php - 分页以显示每页的限制

Question

如何确保我的页面每页最多可以存储 3 个从数据库中获得的结果？我将通过 html 链接从上一页中检索一些值，并使用它从数据库中检索结果。然后从结果中，我希望将它们制作成页面，这样就不必滚动很长时间了。在打开的每个页面上，它都会被禁用。

<?php
if (isset($_GET["w1"]) && isset($_GET["w2"])) {
        $lt = $_GET["w1"];
        $ln = $_GET["w2"];
        $GLOBALS['id']= "";
    }

    $servername = "localhost";
    $username = "root";
    $password = "";

    try {
        $conn = new PDO("mysql:host=$servername;dbname=dbname", $username, $password);
        // set the PDO error mode to exception
        $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    }
    catch(PDOException $e){
        echo "Connection failed: " . $e->getMessage();
    }

    function getAddress($lt, $ln) {
        $result = json_decode(file_get_contents("https://maps.google.com/maps/api/geocode/json?key=". API_KEY ."&latlng=$lt,$ln"));
        if ($result->status == 'OK') {
            return $result->results[0]->formatted_address;
        }
        return 'Error'; 
    }

    try{
        $db = $conn->prepare("Select ID from Table");
        $db->execute();

        echo "<div class='row'>";
        while($row=$db->fetch(PDO::FETCH_OBJ)) {
            $GLOBALS['id'] = $row->ID;

            echo "<div class='col-sm-6 col-md-4'>";

            echo  "<h4 class='media-heading'>", $GLOBALS['id'] ,"</h4>";
            echo    "<span class='fa fa-map-pin'></span> ", getAddress($lt,$ln);
            echo "</div>";

        }
        echo "</div>";

    } catch (PDOException $e) {
        echo "Error: ".$e;
    }


?>
<!--Pagination-->
<div class="row">
    <div class="col-xs-12">
        <nav aria-label="Page navigation" class="text-center">
          <ul class="pagination pagination-lrr">
            <li>
              <a href="#" aria-label="Previous">
                <span aria-hidden="true">&laquo;</span>
              </a>
            </li>
            <li class="active"><a href="#">1</a></li>
            <li><a href="#">2</a></li>
            <li><a href="#">3</a></li>
            <li><a href="#">4</a></li>
            <li><a href="#">5</a></li>
            <li>
              <a href="#" aria-label="Next">
                <span aria-hidden="true">&raquo;</span>
              </a>
            </li>
          </ul>
        </nav>
    </div>
</div>

Answer 1

您必须通过添加 2 个变量来稍微修改您的代码:

• currentPage - 告诉脚本访问者所在的页面
• pagepage - 每页应显示多少条记录

下一步是对 SQL 查询使用 LIMIT 选项。

LIMIT start, amount

我们将使用 currentPage 和 perpage 变量计算起点。

$currentPage = (!isset($_GET['current_page']) || (int)$_GET['current_page'] == 0) ? 1 : $_GET['current_page'];
$perpage = 3; //or whatever you'd like

$limit = $perpage;
$start = ($currentPage-1)*$perpage;

$db = $conn->prepare("Select ID from Table LIMIT $start, $limit");

因此对于第 1 页:

start = (1-1)*3 = 0
limit = 3
Which means: get the first 3 items.

对于第 2 页:

start = (2-1)*3 = 3
limit = 3
Which means: count 3 items and then get the 3 after to them