Why can't this delete the selected data?-PHP Tutorial-php.cn

Why can't this delete the selected data?

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Release： 2016-07-06 13:52:30

Original

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What’s wrong?

<code><!DOCTYPE html>
<html>
<head>
    <title></title>
    <style type="text/css">
    </style>
</head>
<body>
<form method="post">
<?php
        header('content-type:text/html;charset=utf-8;');
        $pdo=new PDO("mysql:host=localhost;dbname=t1","root","");
       $stmt=$pdo->prepare("select name from class");
       $stmt->execute();
       $res=$stmt->fetchall(PDO::FETCH_ASSOC);
       foreach($res as $v){
           echo '<span>'.$v['name'].'<input id="ipt3" type="checkbox" name="name">'.'</span>';
       }
?>
<button type="submit">删除</button>
</form>
<?php
if(isset($_POST['name'])){
        header('content-type:text/html;charset=utf-8;');
        $pdo=new PDO("mysql:host=localhost;dbname=t1","root","");
        $stmt2=$pdo->prepare("delete from class where name=?");
        $stmt2->execute(array($_POST['name']));    
    }
    ?>
</body>
</html>
</code>

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Reply content:

What’s wrong?

<code><!DOCTYPE html>
<html>
<head>
    <title></title>
    <style type="text/css">
    </style>
</head>
<body>
<form method="post">
<?php
        header('content-type:text/html;charset=utf-8;');
        $pdo=new PDO("mysql:host=localhost;dbname=t1","root","");
       $stmt=$pdo->prepare("select name from class");
       $stmt->execute();
       $res=$stmt->fetchall(PDO::FETCH_ASSOC);
       foreach($res as $v){
           echo '<span>'.$v['name'].'<input id="ipt3" type="checkbox" name="name">'.'</span>';
       }
?>
<button type="submit">删除</button>
</form>
<?php
if(isset($_POST['name'])){
        header('content-type:text/html;charset=utf-8;');
        $pdo=new PDO("mysql:host=localhost;dbname=t1","root","");
        $stmt2=$pdo->prepare("delete from class where name=?");
        $stmt2->execute(array($_POST['name']));    
    }
    ?>
</body>
</html>
</code>

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Your code is rather strange.
First let’s talk about why it cannot be deleted:
Your input box does not have a value attribute. So your $_POST['name'] cannot get the value.
You can change it to

<code>echo '<span>'.$v['name'].'<input type="checkbox" name="name" value="'.$v['name'].'"></span>';
</code>

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Then I look at your code. Do you want to delete multiple selections? Then you need to post an array to PHP, then you can modify the name attribute of the input:

<code>echo '<span>'.$v['name'].'<input type="checkbox" name="name[]" value="'.$v['name'].'"></span>';
</code>

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Then the post received using php is like this:

<code>$name = $_POST['name'];//array(name1,name2....)
</code>

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At this time you need to deal with this $name. Change your sql statement to

<code>delete from class where name in (name1,name2,name3...)
</code>

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For example:

<code>$sql = "delete from class where name in (" . trim(str_repeat('?,',count($name)),',') . ")";
$stmt2 = $pdo->prepare($sql);
$stmt2->execute($name);
</code>

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Then, your code for judging is_post is best before outputting the list. Otherwise, you will be output first and then deleted, and you will not see the effect.

Are you just getting started?