分页查询的原理与偏移量的计算方法？
根据数据库，设定每页显示数量，获取偏移量，接收GET参数,用p表示当前页数，需要的参数:totalPage 总页数，totalNumber 一共有多少条数据，pageSize 每页显示多少条数据，currentPage 当前第几页，rangeStart 起始页，rangeEnd 末页。当前偏移量的计算公式: (页数-1)*每页显示的数量，offset = (page-1)*num
实例
<?php
$pdo=new PDO('mysql:host=127.0.0.1;dbname=php','root','root');
$page=isset($_GET['p'])?$_GET['p']:1;
$offset=($page-1)*5;
$sql="select * from staff limit {$offset},5";
$stmt=$pdo->prepare($sql);
$stmt->execute();
$result=$stmt->fetchAll(PDO::FETCH_ASSOC);
$stmt=$pdo->prepare("select COUNT(*) from staff");
$stmt->execute();
$total=$stmt->fetchColumn();
$pages=ceil($total/5);
?>
<!doctype html>
<html>
<head>
<meta charset="UTF-8">
<title>Document</title>
<style>
table ,td{
border: 1px solid black;
}
table{
border-collapse: collapse;
width: 60%;
margin: 30px auto;
text-align: center;
}
tr:first-child{
background-color: lightblue;
}
table caption{
font-size: 20px;
margin-bottom: 15px;
}
h3{
text-align: center;
}
h3 a{
text-decoration: none;
display: inline-block;
border: 1px solid black;
height: 30px;
min-width: 30px;
padding: 0 10px;
background-color: lightblue;
margin-left: 10px;
}
h3 a:hover{
background-color: red;
color: white;
}
form {
display: inline;
}
</style>
</head>
<body>
<table>
<caption>员工信息表</caption>
<tr>
<td>ID</td>
<td>姓名</td>
<td>年龄</td>
<td>性别</td>
<td>工资</td>
</tr>
<?php foreach ($result as $staff):?>
<tr>
<td><?php echo $staff['staff_id'];?></td>
<td><?php echo $staff['name'];?></td>
<td><?php echo $staff['age'];?></td>
<td><?php echo $staff['sex']?'女':'男';?></td>
<td><?php echo $staff['salary'];?></td>
</tr>
<?php endforeach;?>
</table>
<h3>
<a href="http://127.0.0.1/page/demo1.php?p=1">首页</a>
<a href="http://127.0.0.1/page/demo1.php?p=<?php echo (($page-1)==0)?1:($page-1);?>">上一页</a>
<?php for ($i=1;$i<=$pages;$i++):?>
<a href="http://127.0.0.1/page/demo1.php?p=<?php echo $i?>"<?php echo ($i==$page)?'style="background-color:red;"':''?>><?php echo $i?></a>
<?php endfor;?>
<a href="http://127.0.0.1/page/demo1.php?p=<?php echo (($page+1)>$pages)?$pages:($page+1);?>">下一页</a>
<a href="http://127.0.0.1/page/demo1.php?p=<?php echo $pages;?>">尾页</a>
<form action="" method="get">
第
<select name="p" id="">
<?php for($i=1;$i<=$pages;$i++):?>
<option value="<?php echo $i?>"<?php if($i==$page){
echo 'selected';
}?>><?php echo $i?></option>
<?php endfor;?>
</select>
页
<button>跳转</button>
</form>
</h3>
</body>
</html>运行实例 »
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