Undefined Index When Declaring Variable

Question

Why I'm getting an undefined index when declaring variables? Currently using bootstrap.

<?php 

 mysql_connect("localhost", "root", "1234") or die(mysql_error());
 mysql_select_db("newitems") or die(mysql_error());

 $up =  $_POST['update']; 
 mysql_query("UPDATE announcements SET content = $up");


 ?>
 <div class="well well-small text-center">
 <h3>Create an Announcement / Reminder:<br>

 <form class="form-group" id="form-mahasiswa" method="POST" action="ad_post.php">

  <div class="control-group">

    <div class="controls">

        <textarea id="update" name="update"></textarea><br>
        
        <button id="annbtn" class="btn btn-success">Update Announcement</button>

    </div>

</div>

You are using the variable $_POST['update']; which is not set until you post the form. — Jens W
– Jens W, Commented Nov 17, 2014 at 18:36
Does this answer your question? "Notice: Undefined variable", "Notice: Undefined index", and "Notice: Undefined offset" using PHP — Nico Haase
– Nico Haase, Commented Oct 18, 2021 at 7:22

Jens W · Accepted Answer · 2014-11-17 19:34:34Z

1

The update should only take place when you submit the form. Wrap your code inside this condition:

if ($_SERVER['REQUEST_METHOD'] == POST && isset($_POST['update']) { 
   $up = $_POST['update']; 
   mysql_query("UPDATE announcements SET content = $up");
}

answered Nov 17, 2014 at 19:34

Jens W

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2 Comments

Jens W Over a year ago

Also the mysql_* functions are deprecated so consider using the mysqli_* functions. php.net/manual/de/book.mysqli.php

Jens W Over a year ago

And finally it's highly recommended to filter input before using in a query :-) php.net/manual/de/function.filter-input.php

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