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Correction status：qualified
Teacher's comments：
Collection
Collection
1.分页查询的原理：根据sql查询语句LIMIT的偏移量与显示数量
2.偏移量的计算方法：当前偏移量的计算公式 = (页数-1) * 每页显示的数量 offset = (page-1) * num
3.分页查询的实现：
<?php
require './query.php';
use model\Query;
$page=new Query();
// 连接数据库
$page->connect('mysql','127.0.0.1','test','root','');
// 获取当前分页
$currentPage = $page->getPage();
// 获取总页数
$totalPages = $page->getPages('user');
// 获取分页数据
$data = $page->getData('user');
?>
<!DOCTYPE html>
<html lang="zh-CN">
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1">
<!-- 上述3个meta标签*必须*放在最前面，任何其他内容都*必须*跟随其后！ -->
<title>分页查询</title>
<!-- Bootstrap -->
<link href="css/bootstrap.min.css" rel="stylesheet">
</head>
<body>
<div class="container-fluid">
<div class="row">
<div class="col-md-6 col-md-offset-3">
<table class="table table-bordered">
<tbody>
<caption class="h3 text-center">员工信息表</caption>
<tr>
<th>id</th>
<th>name</th>
<th>sex</th>
<th>salary</th>
</tr>
<?php foreach ($data as $row):?>
<tr>
<td><?php echo $row['id'];?></td>
<td><?php echo $row['name'];?></td>
<td><?php echo $row['sex']?'男':'女';?></td>
<td><?php echo $row['salary'];?></td>
</tr>
<?php endforeach;?>
</tbody>
</table>
<nav aria-label="Page navigation">
<ul class="pagination">
<!-- 首页-->
<li>
<a href="http://127.0.0.1/php/15/1.php?p=1">首页</a>
</li>
<!-- 上一页-->
<li>
<a href="http://127.0.0.1/php/15/1.php?p=<?php echo $currentPage-1;?>" aria-label="Previous">
<span aria-hidden="true">«</span>
</a>
</li>
<?php for ($i=1; $i<=$totalPages; $i++):?>
<li>
<a href="http://127.0.0.1/php/15/1.php?p=<?php echo $i;?>"><?php echo $i;?></a>
</li>
<?php endfor;?>
<!-- 下一页-->
<li>
<a href="http://127.0.0.1/php/15/1.php?p=<?php echo $currentPage+1;?>" aria-label="Next">
<span aria-hidden="true">»</span>
</a>
</li>
<!-- 尾页-->
<li>
<a href="http://127.0.0.1/php/15/1.php?p=<?php echo $totalPages;?>">尾页</a>
</li>
</ul>
</nav>
<form action="" method="get">
<select name="p" class="form-control" style="width: 200px;">
<?php for ($i=1; $i<=$totalPages; $i++):?>
<option value="<?php echo $i;?>" <?php if($currentPage==$i){echo 'selected';}?>><?php echo $i;?></option>
<?php endfor; ?>
</select>
<button class="btn btn-default" type="submit">跳转</button>
</form>
</div>
</div>
</div>
<script src="js/jquery.min.js"></script>
<script src="js/bootstrap.min.js"></script>
</body>
</html>点击 "运行实例" 按钮查看在线实例
<?php
/**
* 分页查询类
*/
namespace model;
class Query
{
//起始偏移量
private $offset;
//每页记录数
private $num;
//数据库连接对象
private $pdo;
// 每页查询数
public function __construct($num=5)
{
$this->num=$num;
$this->offset = ($this->getPage()-1)*$this->num;
}
// 连接数据库
public function connect($type,$host,$dbname,$user,$pass)
{
try {
$this->pdo = new \PDO("{$type}:host={$host};dbname={$dbname}",$user,$pass);
} catch (\PDOException $e) {
die($e->getMessage());
}
}
// 获取当前页码
public function getPage()
{
//如果url中存在页码变量p则取之,否则默认为1,即第一页
return isset($_GET['p']) ? $_GET['p'] : 1;
}
// 获取总页数
public function getPages($table)
{
$stmt=$this->pdo->prepare("SELECT COUNT(*) FROM $table");
$stmt->execute();
// 获取记录总数
$total=$stmt->fetchColumn();
// ceil()是向上取整函数
return ceil($total/$this->num);
}
// 获取分页数据
public function getData($table)
{
// 从指定数据表中的获取当前页需要显示的记录
$sql="SELECT *FROM {$table} LIMIT {$this->offset},{$this->num}";
$stmt=$this->pdo->prepare($sql);
$stmt->execute();
// 获取分页数据并返回关联部分
return $stmt->fetchAll(\PDO::FETCH_ASSOC);
}
}点击 "运行实例" 按钮查看在线实例
总结：偏移量 = (当前页码-1)*每页显示的条数数量