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1问答：分页查询的原理与偏移量的计算方法:
答:首先要计算出,有多少个符合查询条件的数据,其次在获取到每页要显示的数据数量,再计算出一共需要用多少页来进行显示,这样就能得到3个变量:总数据个数,每页显示个数,总页数,这样就在做分页查询的时候把这几个数据表现出来即可
2编程: 实现分页查询，要求有上一下，下一页，直接跳到首页和尾页，中间页的生成，以及快速页码跳转功能:
<?php
$pdo = new PDO('mysql:host=127.0.0.1;dbname=user', 'root', 'root');
$page = isset($_GET['p']) ? $_GET['p'] : 1;
$offset = ($page - 1) * 2;
$sql = "SELECT * FROM name LIMIT {$offset},2";
$stmt = $pdo->prepare($sql);
$stmt->execute();
$rows = $stmt->fetchAll(PDO::FETCH_ASSOC);
//获取总记录数
$stmt = $pdo->prepare("SELECT COUNT(*) FROM name");
$stmt->execute();
$total = $stmt->fetchColumn(0);
//获取总页数
$totalPage = ceil($total / 2); //ceil 向上取整
?>
<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport"
content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>手工查询</title>
<style>
table, th, td {
border: 1px solid black;
}
table th {
background-color: lightseagreen;
}
table {
border-collapse: collapse;
width: 60%;
margin: 30px auto;
text-align: center;
}
table caption {
font-size: 1.5rem;
margin-bottom: 15px;
}
h3 {
text-align: center;
}
h3 a {
text-decoration-line: none;
margin-left: 10px;
border: 1px solid black;
border-radius: 15px;
display: inline-block;
height: 30px;
min-width: 20px;
padding: 0 10px;
background-color: green;
color: black;
}
h3 a:hover {
background-color: red;
color: white;
}
form {
display: inline;
}
</style>
</head>
<body>
<table>
<caption>员工信息表</caption>
<tr>
<th>ID</th>
<th>姓名</th>
<th>年龄</th>
</tr>
<?php foreach ($rows as $row): ?>
<tr>
<td><?php echo $row['id'] ?></td>
<td><?php echo $row['name'] ?></td>
<td><?php echo $row['age'] ?></td>
</tr>
<?php endforeach; ?>
</table>
<h3>
<a href="http://www.php.io/0910/demo1.php?p=1">首页</a>
<a href="http://www.php.io/0910/demo1.php?p=<?php echo (($page - 1) == 0) ? 1 : ($page - 1); ?>">上一页</a>
<?php for ($i = 1; $i <= $totalPage; $i++): ?>
<a href="http://www.php.io/0910/demo1.php?p=<?php echo $i; ?>"
<?php echo ($i == $page) ? 'style="background-color:yellow;color:red"': '';?>
><?php echo $i ?></a>
<?php endfor; ?>
<a href="http://www.php.io/0910/demo1.php?p=<?php echo (($page + 1) > $totalPage) ? $totalPage : $page + 1; ?>">下一页</a>
<a href="http://www.php.io/0910/demo1.php?p=<?php echo $totalPage; ?>">尾页</a>
<form action="" method="get">
第
<select name="p" id="">
<?php for ($i=1;$i<=$totalPage;$i++):?>
<option value=<?php echo $i?>><?php echo $i?></option>
<?php endfor;?>
</select>
页
<button>跳转</button>
</form>
</h3>
</body>
</html>点击 "运行实例" 按钮查看在线实例
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