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PHP实战分页显示和分页导航
吾逍遥
Original
2165 people have browsed it

一、分页原理

数据分页其实就是SQL构造语句的Limit使用，其有两种形式:SELECT * FROM user LIMIT 0,10;和SELECT * FROM USER LIMIT 10 OFFSET 0;。若是LIMIT 0,10则偏移量是0，10是记录条数，而是使用LIMIT 10 OFFSET 0表示意思是一样的，即若LIMIT后面只有一个数字，则表示取得记录条数。

关于偏移量的计算是offset=(page-1)*num;。page是当前页的页码，即是index.php?p=2中2。num则表示每页要显示的记录条数。

二、封装的PDO数据库操作类

写本博文开始自己封装常用的类了，如数据库类Db，目前是第一版，实现了数据库链式查询和CURD操作，至于预处理和事务则后续版本中逐渐增加。

  1. declare(strict_types=1);
  3. namespace WOXIAOYAO;
  5. use \PDO;
  6. use \Exception;
  8. /*
  9.  * @Descripttion: 自己封装的PDO类，可支持MySQL、MSSQL、ORACLE和SQLite的数据库操作
  10.  * @version: 1.0.0
  11.  * 准备要完成功能:1、支持PDO的query和exec(1.0.0)  2、支持PDO的预处理   3、支持PDO的事务处理
  12.  */
  14. //  准备知识:四种数据库连接方式
  15. //  MySQL:'dsn'=>'mysql:host=localhost;dbname=talk','username'=>'root','password'=>'123456'
  16. //  MSSQL:'dsn'=>'odbc:Driver={SQL Server};Server=192.168.1.60;Database=his','username'=>'sa','password'=>'xxxxx'
  17. //  Oracle:'dsn'=>'oci:dbname=orcl','username'=>'BAOCRM','password'=>'BAOCRM'
  18. //  SQLite:'dsn'=>'sqlite:'.dirname(__FILE__).'\log.db'
  20. // 抽象类完成单例模式连接、准备处理方法和接口的定义
  21. // 抽象类的保护静态成员为所有子类共享
  22. abstract class aDb
  23. {
  24.     // 定义单例模式连接
  25.     protected static $pdo = null;
  26.     protected static $config = null;
  27.     final protected function connect(array $config)
  28.     {
  29.         $config = array_change_key_case($config, CASE_LOWER);
  30.         if ($config === false) throw new Exception('连接配置不是数组');
  31.         if (empty($this->is_assoc($config))) throw new Exception('连接配置不是关联数组');
  32.         if (empty(self::$config)) {
  33.             self::$config = $config;
  34.         } else if (!empty(array_diff_assoc(self::$config, $config))) {
  35.             self::$config = $config;
  36.         } else {
  37.             return self::$pdo;
  38.         }
  39.         try {
  40.             $pdo = new \PDO(self::$config['dsn'], self::$config['username'], self::$config['password']);
  41.             // 若没报错则先清除旧连接，重置为新连接
  42.             self::$pdo = null;
  43.             self::$pdo = $pdo;
  44.             self::$pdo->query("set names utf8");
  45.             //属性名 属性值 数组以关联数组返回
  46.             self::$pdo->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE, PDO::FETCH_ASSOC);
  47.             self::$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_WARNING);
  48.         } catch (\Exception $e) {
  49.             echo '数据库连接失败,详情: ' . $e->getMessage() . ' 请在配置文件中数据库连接信息';
  50.             exit();
  51.         }
  52.     }
  54.     // 判断是否是关联数组
  55.     final protected function is_assoc(array $arr)
  56.     {
  57.         if (is_array($arr)) {
  58.             $key = array_keys($arr);
  59.             return $key === array_keys($key) ? false : true;
  60.         }
  61.         return null;
  62.     }
  64.     // 定义接口规范
  65.     // 链式规范
  66.     abstract public function table(string $table);
  67.     abstract public function field(string $fields);
  68.     abstract public function where($where);
  69.     abstract public function order(string $order);
  70.     abstract public function limit(string $limit);
  71.     // 单条记录和多条记录查询
  72.     abstract public function find();
  73.     abstract public function select();
  74.     // 插入、更新和删除规范
  75.     abstract public function insert(array $data);
  76.     abstract public function update(array $data);
  77.     abstract public function delete();
  78. }
  80. // 工作类，实现CURD操作
  81. class Db extends aDb
  82. {
  83.     private $res;
  84.     private $table;
  85.     private $fields = '*';
  86.     private $where = 'true';
  87.     private $order;
  88.     private $limit;
  90.     function __construct(array $config)
  91.     {
  92.         $this->connect($config);
  93.     }    
  94.     function getConfig()
  95.     {
  96.         return parent::$config;
  97.     }
  98.     function getPDO()
  99.     {
  100.         return parent::$pdo;
  101.     }
  102.     private function reset(){
  103.         // $table='';
  104.         $this->fields = '*';
  105.         $this->where = 'true';
  106.         $this->order = '';
  107.         $this->limit = '';
  108.     }
  110.     // 链式查询
  111.     function table(string $table)
  112.     {
  113.         if (!is_string($table)) throw new Exception("参数是字符串，形式如'user'表示user表");
  114.         if (!empty($table))
  115.             $this->table = $table;
  116.         return $this;
  117.     }
  118.     function field(string $fields)
  119.     {
  120.         if (!is_string($fields)) throw new Exception("参数是字符串，形式如'id,name,pwd'表示获取3个字段");
  121.         if (!empty($fields))
  122.             $this->fields = $fields;
  123.         return $this;
  124.     }
  125.     function where($where)
  126.     {
  127.         if (is_string($where)) {
  128.             if (!empty($fields))
  129.                 $this->where .= " and {$where}";
  130.             return $this;
  131.         }
  132.         if ($this->is_assoc($where)) {
  133.             while (current($where)) {
  134.                 $this->where .= ' and ' . key($where) . '=' . current($where);
  135.                 next($where);
  136.             }
  137.             return $this;
  138.         }
  139.         throw new Exception('请检查条件');
  140.     }
  141.     function order(string $order)
  142.     {
  143.         if (!is_string($order)) throw new Exception("参数是字符串，形式如'id asc'表示id升序");
  144.         if (!empty($order))
  145.             $this->order = $order;
  146.         return $this;
  147.     }
  148.     function limit(string $limit)
  149.     {
  150.         if (!is_string($limit)) throw new Exception("参数是字符串，形式如'0,5'表示偏移0数量是5");
  151.         if (!empty($limit))
  152.             $this->limit = $limit;
  153.         return $this;
  154.     }
  155.     // 查询单条记录
  156.     function find()
  157.     {
  158.         try {
  159.             if (empty($this->table)) throw new Exception('没有查询表');
  160.             $sql = "SELECT {$this->fields} FROM {$this->table} WHERE {$this->where}";
  161.             if (!empty($this->order))
  162.                 $sql .= " ORDER BY {$this->order}";
  163.             $this->res = parent::$pdo->query($sql);
  164.             $this->reset();
  165.             return $this->res->fetch(PDO::FETCH_ASSOC);
  166.         } catch (\PDOException $e) {
  167.             return '查询错误信息：' . $e->getMessage();
  168.         }
  169.     }
  170.     // 查询所有记录
  171.     function select()
  172.     {
  173.         try {
  174.             if (empty($this->table)) throw new Exception('没有查询表');
  175.             $sql = "SELECT {$this->fields} FROM {$this->table} WHERE {$this->where}";
  176.             if (!empty($this->order))
  177.                 $sql .= " ORDER BY {$this->order}";
  178.             if (!empty($this->limit))
  179.                 $sql .= " LIMIT {$this->limit}";
  180.             $this->res = parent::$pdo->query($sql);
  181.             $this->reset();
  182.             return $this->res->fetchAll(PDO::FETCH_ASSOC);
  183.         } catch (\PDOException $e) {
  184.             return '查询错误信息：' . $e->getMessage();
  185.         }
  186.     }
  188.     // 插入、更新和删除操作
  189.     public function insert(array $data)
  190.     {
  191.         if (empty($this->is_assoc($data))) throw new Exception('插入数据不是关联数组');
  192.         if (empty($this->table)) throw new Exception('插入时必须指定表');
  193.         $sql = "INSERT INTO {$this->table}";
  194.         $key = key($data);
  195.         $value = "'" . current($data) . "'";
  196.         next($data);
  197.         while (current($data)) {
  198.             $key .= "," . key($data);
  199.             $value .= ",'" . current($data) . "'";
  200.             next($data);
  201.         }
  202.         $sql .= " ({$key}) VALUES ({$value})";
  203.         $this->res = parent::$pdo->exec($sql);
  204.         $this->reset();
  205.         return $this->res;
  206.     }
  207.     public function update(array $data)
  208.     {
  209.         if (empty($this->is_assoc($data))) throw new Exception('更新数据不是关联数组');
  210.         if (empty($this->table)) throw new Exception('更新时必须指定表');
  211.         if ($this->where == 'true') throw new Exception('更新时必须指定条件');
  212.         $sql = "UPDATE {$this->table}";
  213.         $item = key($data) . "='" . current($data) . "'";
  214.         next($data);
  215.         while (current($data)) {
  216.             $item .= "," . key($data) . "='" . current($data) . "'";
  217.             next($data);
  218.         }
  219.         $sql .= " SET {$item} WHERE {$this->where}";
  220.         $this->res = parent::$pdo->exec($sql);
  221.         $this->reset();
  222.         return $this->res;
  223.     }
  224.     public function delete()
  225.     {
  226.         try {
  227.             if (empty($this->table)) throw new Exception('删除时必须指定表');
  228.             if ($this->where == 'true') throw new Exception('删除时必须指定条件');
  229.             $sql = "DELETE FROM {$this->table} WHERE {$this->where}";
  230.             $this->res = parent::$pdo->exec($sql);
  231.             $this->reset();
  232.             return $this->res;
  233.         } catch (\PDOException $e) {
  234.             return '查询错误信息：' . $e->getMessage();
  235.         }
  236.     }
  237. }

三、基础版的分页

上面已经准备了数据库，也理解了分页的知识，下面代码反而比较简单，直接看代码

  1. //pagnate.php
  2. require_once 'Db.php';
  4. use WOXIAOYAO\Db;
  6. $config = [
  7.     'dsn' => 'mysql:host=localhost;dbname=test',
  8.     'username' => 'root',
  9.     'password' => 'root'
  10. ];
  11. $obj = new Db($config);
  13. //分页获取数据
  14. $num = 10;
  15. $res = $obj->table('user')->field('count(id) as total')->select();
  16. $total = intval($res[0]['total']);
  17. $pages = ceil($total / $num);
  18. $page = $_GET['p'] ?? 1;
  19. $offset = ($page - 1) * $num;
  20. $users = $obj->table('user')->limit("{$offset},{$num}")->select();
  1. // index.php
  2. <style>
  3.     * {
  4.         margin: 0;
  5.         padding: 0;
  6.         box-sizing: border-box;
  7.     }
  9.     a {
  10.         text-decoration: none;
  12.         display: inline-block;
  13.         /* width: 2em; */
  14.         height: 2em;
  15.         line-height: 2em;
  16.     }
  18.     .container {
  19.         width: 60vw;
  20.         margin: 1em auto;
  21.     }
  23.     td {
  24.         text-align: center;
  25.     }
  27.     .page {
  28.         margin-top: 1em;
  29.         text-align: center;
  30.     }
  32.     td a:first-child {
  33.         margin-right: 5px;
  34.     }
  36.     td a:last-child {
  37.         margin-left: 5px;
  38.     }
  40.     .page a {
  41.         padding: 0 0.5em;
  42.         margin: 0 5px;
  43.     }
  45.     .page a.cur {
  46.         background-color: #007d20;
  47.         color: white;
  48.     }
  49. </style>
  50. <div class="container">
  51.     <table border='1' cellspacing="0" width="100%">
  52.     <caption>用户信息表</caption>
  53.         <thead>
  54.             <tr bgColor="lightgray">
  55.                 <th>ID</th>
  56.                 <th>name</th>
  57.                 <th>password</th>
  58.                 <th>操作</th>
  59.             </tr>
  60.         </thead>
  61.         <tbody>
  62.             <?php
  63.             include_once 'pagnate.php';
  64.             foreach ($users as $user) {
  65.                 $trdata = "<tr>";
  66.                 foreach ($user as $item) {
  67.                     $trdata .= "<td>{$item}</td>";
  68.                 }
  69.                 $trdata .= "<td><a href='#'>编辑</a><a href='#'>删除</a></td>";
  70.                 $trdata .= "</tr>";
  71.                 echo $trdata;
  72.             }
  73.             ?>
  74.         </tbody>
  75.     </table>
  76.     <div class="page">
  77.         <?php
  78.         echo "<a href='{$_SERVER["PHP_SELF"]}?p=1'>首页</a>";
  79.         $prev = ($page - 1 > 1) ? ($page - 1) : 1;
  80.         if ($page > 1)
  81.             echo "<a href='{$_SERVER["PHP_SELF"]}?p={$prev}'>上一页</a>";
  82.         for ($i = 1; $i <= $pages; $i++) :
  83.             if ($i == $page)
  84.                 echo "<a class='cur' href='{$_SERVER["PHP_SELF"]}?p={$i}'>{$i}</a>";
  85.             else
  86.                 echo "<a href='{$_SERVER["PHP_SELF"]}?p={$i}'>{$i}</a>";
  87.         endfor;
  88.         $next = ($page + 1) < $pages ? ($page + 1) : $pages;
  89.         if ($page < $pages)
  90.             echo "<a href='{$_SERVER["PHP_SELF"]}?p={$next}'>下一页</a>";
  91.         echo "<a href='{$_SERVER["PHP_SELF"]}?p={$pages}'>未页</a>";
  92.         ?>
  93.     </div>
  94. </div>

四、对分页导航栏的改进

无论是PHP中文网或老师演示的省略号仅仅展示，而无实际功能，而我认为前省略号相当于前一页，后面省略号相当于后一页。具体代码我在老师的基础上进行了精简。下面分布导航既有老师所演示的省略号功能，而且省略号也能起到跳转页码作用。

  1. //pagnate.php
  2. // 改进的导航栏（在基础版中增加）
  3. $startPage = 1;
  4. // 显示页码数最好为奇数
  5. $showPage = 5;
  6. if (($page - ceil(($showPage - 1) / 2)) > $startPage)
  7.     $startPage = $page - ceil(($showPage - 1) / 2);
  1. //index2.php
  2. // 分页数据代码不变，对分页页码导航代码重新编写
  3. <div class="page">
  4.     <?php
  5.     echo "<a href='{$_SERVER["PHP_SELF"]}?p=1'>首页</a>";
  6.     $prev = ($page - 1 > 1) ? ($page - 1) : 1;
  7.     if ($startPage > 1)
  8.         echo "<a href='{$_SERVER["PHP_SELF"]}?p={$prev}'>...</a>";
  9.     for ($i = $startPage; $i < $startPage+$showPage; $i++) :
  10.         if ($i == $page)
  11.             echo "<a class='cur' href='{$_SERVER["PHP_SELF"]}?p={$i}'>{$i}</a>";
  12.         else
  13.             echo "<a href='{$_SERVER["PHP_SELF"]}?p={$i}'>{$i}</a>";
  14.     endfor;
  15.     $next = ($page + 1) < $pages ? ($page + 1) : $pages;
  16.     if ($startPage+$showPage <= $pages+1)
  17.         echo "<a href='{$_SERVER["PHP_SELF"]}?p={$next}'>...</a>";
  18.     echo "<a href='{$_SERVER["PHP_SELF"]}?p={$pages}'>未页</a>";
  19.     ?>
  20. </div>

pagnate

关于单条数据的编辑和删除: 其实就是数据库的更新和删除操作，比较简单，我这里就不演示了

Correcting teacher：灭绝师太灭绝师太

Correction status：qualified

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