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Correction status：qualified
Teacher's comments：
Collection
Collection
今天学习了分面查询原理与类封装的知识。
分页查询的原理与偏移量的计算方法
1. LIMIT 参数的作用: 偏移量与显示数量
2. 如果控制每页显示的数量
3. 接收GET参数,用p表示当前页数,每页显示3条
4. 需要的参数:
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
代码
<?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();
$rows=$stmt->fetchAll(PDO::FETCH_ASSOC);
//var_dump($rows);
$stmt=$pdo->prepare("select count(*) from staff");
$stmt->execute();
$totals=$stmt->fetchColumn(0);
$pages=ceil($totals/5);
?>
<!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>分页查询</title>
<style>
table,th,td{
border: 1px solid black;
}
table{
border-collapse: collapse;
width: 60%;
margin: 30px auto;
text-align: center;
}
th{
background-color: aquamarine;
margin-bottom: 15px;
}
caption{
font-size: 1.5rem;
margin-bottom: 15px;
}
h3{
text-align: center;
}
h3 a{
text-decoration-line: none;
display: inline-block;
height: 30px;
min-width: 30px;
border: 1px solid black;
background-color: aqua;
color: black;
padding: 0 10px;
}
a:hover{
background-color: red;
color:white;
}
form{
display: inline;
}
</style>
</head>
<body>
<table>
<caption>员工信息表</caption>
<tr>
<th>staff_id</th>
<th>name</th>
<th>sex</th>
<th>age</th>
<th>salary</th>
</tr>
<?php foreach ($rows as $row):?>
<tr>
<td><?php echo $row['staff_id'];?></td>
<td><?php echo $row['name'];?></td>
<td><?php echo $row['sex']?'女':'男';?></td>
<td><?php echo $row['age'];?></td>
<td><?php echo $row['salary'];?></td>
</tr>
<?php endforeach;?>
</table>
<h3><a href="http://php.io/15/demo4.php?p=1">首页</a>
<a href="http://php.io/15/demo4.php?p=<?php echo ($page-1==0)?1:($page-1) ;?>">上一页</a>
<?php for($i=1;$i<$pages;$i++):?>
<a href="http://php.io/15/demo4.php?p=<?php echo $i;?>" <?php echo ($i==$page)?"style=background-color:red":'';?>><?php echo $i;?></a>
<?php endfor;?>
<a href="http://php.io/15/demo4.php?p=<?php echo ($page+1>$pages)?$pages:($page+1);?>">下一页</a>
<a href="http://php.io/15/demo4.php?p=<?php echo $pages;?>">尾页</a>
<form action="" method="get">
<select name="p" id="">
<?php for($i=1;$i<$pages;$i++):;?>
<option value="<?php echo $i;?>"<?php if($i==$page){
echo 'selected';
}?>><?php echo $i;?></option>
<?php endfor;?>
</select>
<button>提交</button>
</form>
</h3>
</body>
</html>点击 "运行实例" 按钮查看在线实例
