PHP分页

1.连接数据库

<?php
//连接数据库
$pdo = new PDO('mysql:host=localhost;dbname=tp5','root','wang1111');
//设置默认的提取模式
$pdo->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE,PDO::FETCH_ASSOC);

2.分页原理

<?php
//分页原理
//SELECT * FROM `user` 每页的数量 显示的偏移量
//每页显示的数量  LIMIT n
//显示的偏移量：从哪个索引开始 OFFSET m
//偏移量 = （页码-1）* 每页的显示数量
require 'connect.php';
//获取分页数据，一定要知道的二个数据
//1.每页显示的数量
$num = 5;
//2.当前页码
$page = $_GET['p'] ?? 1;
//3.计算每一页的第一条记录的显示偏移量
$offset = ($page-1)*$num;
//4.获取分页数据
$sql = "SELECT * FROM `user` LIMIT {$num} OFFSET {$offset}";
$users = $pdo->query($sql)->fetchAll();
//print_r($users);
//计算总页数
//ceil()向上取整
//总页数 = ceil(记录总数/每页的记录数)
$sql = "SELECT CEIL(COUNT(`id`)/{$num}) AS `total` FROM `user`";
$pages = $pdo->query($sql)->fetch()['total'];
//print_r($res);

3.显示分页

<?php require 'demo1.php'; ?>
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>数据展示</title>
    <style>
        body{
            padding:0;
            margin:0;
            box-sizing:border-box;
            display:flex;
            justify-content:center;
        }
        thead > tr{
            background:#77DDFF;
        }
        table{
            text-align:center;
            width:800px;
        }
        caption{
            padding:10px 0;
        }
        .delete{
            color:#E63F00;
        }
        p{
            display:flex;
            justify-content:center;
        }
        p > a{
            display:block;
            border:1px solid #000;
            text-align:center;
            text-decoration:none;
            width:20px;
            height:20px;
            color:#000;
            margin:0 5px;
        }
        p > a:hover{
            background:#000;
            color:#fff;
            border:1px solid #fff;
        }
        .active{
            background:#000;
            color:#fff;
            border:1px solid #fff;
        }
        .shouye{
            width:40px;
            height:20px;
            font-size:15px;
        }
        .shang{
            width:60px;
            height:20px;
            font-size:15px;
        }
    </style>
</head>
<body>
<div>
    <table border="1px" cellspacing="0" cellpadding="10px">
        <caption>用户信息表</caption>
        <thead>
            <tr>
                <td>id</td>
                <td>name</td>
                <td>username</td>
                <td>操作</td>
            </tr>
        </thead>
        <tbody>
            <?php foreach ($users as $user): ?>
                <tr>
                    <td><?=$user['id']?></td>
                    <td><?php echo $user['name'] ?></td>
                    <td><?php echo $user['username'] ?></td>
                    <td>
                        <button onclick="location.href='handle.php?action=edit&id=<?=$user['id']?>'">编辑</button>
                        <button class="delete" onclick="del(<?=$user['id']?>)">删除</button></td>
                </tr>
            <?php endforeach; ?>
        </tbody>
    </table>
    <!-- 分页条 -->
    <p>
        <?php 
            $previous = $page-1;
            if($previous < 1) $previous = 1;
        ?>
        <?php if($page != 1): ?>
        <a href="<?=$_SERVER['PHP_SELF']?>?p=1" class="shouye">首页</a>
        <a href="<?=$_SERVER['PHP_SELF']?>?p=<?=$previous?>" class="shang">上一页</a>
        <?php endif; ?>
        <!-- ********************************************************** -->
        <?php 
            if($page<=10):
            for($i=1;$i<=10;$i++): 
        ?>
        <?php 
            $jump = sprintf('%s?p=%s',$_SERVER['PHP_SELF'],$i );
            //当前页码与当前页相等的时候
            $active = ($i == $page) ? 'active' : null;
        ?>
        <!-- 将类名变量化 -->
        <a href="<?=$jump?>" class="<?=$active?>"><?=$i?></a>
        <?php 
            endfor;
            endif;
        ?>
        <!-- ********************************************************** -->
        <?php 
           //$twenty = ceil($page/10)*10;
           //$ten = floor($page);
           $a = $page + 5;
           $b = $page -4;
           $c = $pages - 10;
            if($page>10 && $page < $c):
            for($i=$b;$i<=$a;$i++): 
        ?>
        <?php 
            $jump = sprintf('%s?p=%s',$_SERVER['PHP_SELF'],$i );
            //当前页码与当前页相等的时候
            $active = ($i == $page) ? 'active' : null;
        ?>
        <!-- 将类名变量化 -->
        <a href="<?=$jump?>" class="<?=$active?>"><?=$i?></a>
        <?php 
            endfor;
            endif;
        ?>
        <!-- ********************************************************** -->
        <?php 
           $c = $pages - 10;
            if($page>=$c):
            for($i=$c;$i<=$pages;$i++): 
        ?>
        <?php 
            $jump = sprintf('%s?p=%s',$_SERVER['PHP_SELF'],$i );
            //当前页码与当前页相等的时候
            $active = ($i == $page) ? 'active' : null;
        ?>
        <!-- 将类名变量化 -->
        <a href="<?=$jump?>" class="<?=$active?>"><?=$i?></a>
        <?php 
            endfor;
            endif;
        ?>
        <!-- ********************************************************** -->
        <?php 
            $next = $page+1;
            if($next >= $pages) $next = $pages;
        ?>
        <?php if($page < $pages): ?>
        <a href="<?=$_SERVER['PHP_SELF']?>?p=<?=$next?>" class="shang">下一页</a>
        <a href="<?=$_SERVER['PHP_SELF']?>?p=<?=$pages?>" class="shouye">尾页</a>
        <?php endif; ?>
    </p>
    <script>
    //删除
    function del(id){
        str = 'handle.php?action=delete&id=';
        str+=id;
        if(confirm('是否删除？')){
             location.href=str; 
        }
    }
    </script>
</div>
</body>
</html>

4.编辑与删除

编辑页面：

<?php
//获取要被编辑的数据
$user = $pdo->query('SELECT * from `user` where `id` =' . $id)->fetch();
print_r($user);
?>
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>用户编辑</title>
</head>
<body>
    <form action="<?php echo $_SERVER['PHP_SELF'] . '?action=doedit&id='.$id?>" method="post">
    <p>
    <label for="name">用户名</label>
    <input type="text" name="name" id="name" value="">
    </p>
    <p>
    <label for="username">账号名</label>
    <input type="text" name="username" id="username" value="">
    </p>
    <input type="hidden" name="id" value="">
    <p>
    <button>保存</button>
    </p>
    </form>
</body>
</html>

删除页面

<?php
require 'connect.php';
//获取操作
$action = $_GET['action'];
$id= $_GET['id'];
switch ($action){
    //编辑操作
    case 'edit':
        include 'edit.php';
    break;
    //2.执行编辑操作
    case 'doedit':
        //更新
        $sql = 'UPDATE `user` SET `name`=?, `username`=? where `id`=?';
        $stmt = $pdo->prepare($sql);
        //新的数据在$_Post
        if(!empty($_POST)){
            $stmt->execute([$_POST['name'],$_POST['username'],$id]);
            if($stmt->rowCount() == 1) echo '<script>alert("更新成功");location.href="demo2.php"</script>';
        }
    break;
    //3.删除
    case 'delete':
        $sql = "DELETE FROM `user` where `id`=" . $id;
        $res = $pdo->exec($sql);
        if($res){
            echo '<script>alert("删除成功");location.href="demo2.php"</script>';
        }
    break;
}

5.学习总结

分页要确定每页显示几条数据，当前页码，总记录数，总页数(向上取整)，然后通过循环遍历数据库中的内容，编辑需要跳转到一个编辑表单中更改数据，然后保存到数据库中，报存成功，提示更新成功并跳转；删除直接执行删除语句，如果删除成功则提示删除成功并跳转。

Correcting teacher：

天蓬老师

Correction status：qualified

Teacher's comments：非常棒

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