php分页原理与实现
主要知识点
1）分页查询的原理
a. LIMIT 参数的作用: 偏移量与显示数量
b. 控制每页显示的数量
c. 接收GET参数,用page表示当前页数,每页显示设置的数量
d. 需要基本的参数：总页数，当前页，每页显示数量，偏移量
2）当前偏移量的计算公式：当前偏移量 = ( 当前页 - 1 ) * 每页显示数量
代码
Page.php
<?php
namespace page;
class Page
{
// 偏移量
private $offset;
// 每页记录数量
private $pageNums;
// 数据库连接
private $pdo;
public function __construct($pageNums=5)
{
// 每页记录的数量
$this->pageNums = $pageNums;
// 查询起始偏移量: (页码-1)*数量
$this->offset = ($this->getPage()-1)*$this->pageNums;
}
// 连接数据库
public function connect($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()
{
return isset($_GET['page']) ? $_GET['page'] : 1;
}
// 获取总页数
public function getTotalPages($table)
{
$stmt = $this->pdo->prepare("SELECT COUNT(*) FROM {$table}");
$stmt->execute();
$total = $stmt->fetchColumn(0);
$totalPages = ceil($total / $this->pageNums);
return $totalPages;
}
// 获取分页数据
public function getPageData($table)
{
$sql = "SELECT * FROM `{$table}` LIMIT {$this->offset}, {$this->pageNums} ";
$stmt = $this->pdo->prepare($sql);
$stmt->execute();
return $stmt->fetchAll(\PDO::FETCH_ASSOC);
}
}demo1.php
<?php
require "Page.php";
use page\Page;
$page = new Page(3);
// 连接数据库
$page->connect('mysql','127.0.0.1','php','root','root');
// 获取当前页
$currentPage = $page->getPage();
// 获取总页数
$totalPages = $page->getTotalPages('staff');
// echo $totalPages;die();
//获取分页数据
$data = $page->getPageData('staff');
?>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
<style type="text/css">
a{
display:inline-block;
text-decoration:none;
background:#C2C2C2;
color: #1E90FF;
padding: 8px;
}
a.active{
color: #fff;
}
table{
margin: 0 auto;
}
div{
margin-top:20px;
text-align:center;
}
form{
display:inline-block;
}
</style>
</head>
<body>
<table>
<caption>员工信息表</caption>
<tr>
<th>ID</th>
<th>姓名</th>
<th>年龄</th>
<th>性别</th>
<th>工资</th>
</tr>
<?php foreach($data as $row): ?>
<tr>
<td><?php echo $row['staff_id']; ?></td>
<td><?php echo $row['name']; ?></td>
<td><?php echo $row['age']; ?></td>
<td><?php echo $row['sex']?'男':'女'; ?></td>
<td><?php echo $row['salary']; ?></td>
</tr>
<?php endforeach;?>
</table>
<div>
<?php if($currentPage != 1): ?>
<a href="http://127.0.0.1/test/0910/demo1.php?page=1">首页</a>
<a href="http://127.0.0.1/test/0910/demo1.php?page=<?php
echo $currentPage-1
?>">上一页</a>
<?php endif; ?>
<?php for($i=1; $i<=$totalPages; $i++): ?>
<a class="<?php echo $currentPage==$i? 'active' : '' ; ?>" href="http://127.0.0.1/test/0910/demo1.php?page=<?php
echo $i;
?>"><?php echo $i; ?></a>
<?php endfor; ?>
<?php if($currentPage != $totalPages) :?>
<a href="http://127.0.0.1/test/0910/demo1.php?page=<?php
echo $currentPage+1;
?>">下一页</a>
<a href="http://127.0.0.1/test/0910/demo1.php?page=<?php echo $totalPages; ?>">尾页</a>
<?php endif; ?>
<form action="" method="get">
第
<select name="page" id="">
<?php for($i=1; $i<=$totalPages; $i++): ?>
<option value="<?php echo $i; ?>" ><?php echo $i; ?></option>
<?php endfor;?>
</select>
页
<button>跳转</button>
</form>
</div>
</body>
</html>运行结果
