PHP error: Undefined variable [duplicate] - php

Question

This question already has answers here:
"Notice: Undefined variable", "Notice: Undefined index", "Warning: Undefined array key", and "Notice: Undefined offset" using PHP
(29 answers)
Closed 8 years ago.
I am trying to delete some rows when users check them with check button. I have created a button called delete, but I have a problem. It said to me that variable delete that I use here
// Check if delete button active, start this if($delete){ for($i=0;$i<$count;$i++){ $del_id = $checkbox[$i]; $sql = "DELETE FROM Aktivitet WHERE Id_Akt='$del_id'"; $result = mysql_query($sql); } is not defined... But why because I have declared it as the name of Delete button...here I have created the Delete button;
print("<tr>");
print("<td><input name='delete' type='submit' id='delete' value='Delete'></td>");
print("</tr>");
Please can you help me? What can I do? My php file is below:
<?php
$con = mysql_connect('127.0.0.1','root','');
if (!$con)
{
die('Lidhja me databazen nuk mund te kryhet' .mysql_error(). ' </body></html>');
}
if(!mysql_select_db("Axhenda",$con))
die('Nuk mund te hapet databaza Axhenda'.mysql_error(). '</body></html>');
$result = mysql_query("SELECT * FROM Aktiviteti where Data= '$_POST[dataoutput]'");
mysql_close($con);
?>
<div class="title"> Aktivitetet per daten <?php print ("$_POST[dataoutput]"); ?></div>
<table>
<?php
print("<th >");
print("<form name='form1' method='post' action=''>");
print("<td>Emertimi takimit</td>");
print("<td>Pershkrimi takimit</td>");
print("<td>Oraa takimit</td>");
print("</th >");
while($rows=mysql_fetch_row($result))
{
if (!empty($rows))
{
print("<tr >");
print("<td align='center' bgcolor='#FFFFFF'><input
name='checkbox[]' type='checkbox' id='checkbox[]' value='$rows[0]'></td>");
print("<td bgcolor='#FFFFFF'>$rows[2]</td>");
print("<td bgcolor='#FFFFFF'>$rows[3]</td>");
print("<td bgcolor='#FFFFFF'>$rows[5]</td>");
print("</tr>");
}
else
echo "ska aktivitet";
}
print("<tr>");
print("<td><input name='delete' type='submit' id='delete' value='Delete'></td>");
print("</tr>");
?>
<?php
// Check if delete button active, start this
if($delete){
for($i=0;$i<$count;$i++){
$del_id = $checkbox[$i];
$sql = "DELETE FROM Aktivitet WHERE Id_Akt='$del_id'";
$result = mysql_query($sql);
}
// if successful redirect to delete_multiple.php
if($result){
echo "<meta http-equiv=\"refresh\" content=\"0;URL=delete_multiple.php\">";
}
}
print("</form>");
?>
</table>
I modified the function like below, but it still dont delete anything:
if(isset($_POST['delete'])){
$checkbox = $_POST['checkbox'];
$count = count($checkbox);
for($i = 0; $i < $count; $i++) {
$id = (int) $checkbox[$i];
if ($id > 0) { // and check if it's bigger then 0
mysql_query("DELETE FROM Aktiviteti WHERE Id_Akt= $id");
}
}
}
please help me..

Answer 1

Tested on my own server. You will need to modify it for your own columns as well as other elements that need to be translated in your language.
Change settings for the following:
DEFINE ('DB_HOST', 'xxx');
DEFINE ('DB_USER', 'xxx');
DEFINE ('DB_PASSWORD', 'xxx');
DEFINE ('DB_NAME', 'xxx');
And: (Note: the # is just a reference character. You can change it to what you like.)
<td align="center" bgcolor="#FFFFFF">#</td>
<td align="center" bgcolor="#FFFFFF"><strong>Link ID</strong></td>
<td align="center" bgcolor="#FFFFFF"><strong>Link Name</strong></td>
<td align="center" bgcolor="#FFFFFF"><strong>Link Email</strong></td>
And change: (The rows you wish to show up. There are two of these. One is to show the rows, while the other is used for deletion.)
<td bgcolor="#FFFFFF"><?php echo $row['id']; ?></td>
<td bgcolor="#FFFFFF"><?php echo $row['name']; ?></td>
<td bgcolor="#FFFFFF"><?php echo $row['email']; ?></td>
And change: (delete.php is this file to redirect to after deleting)
echo "<meta http-equiv=\"refresh\" content=\"3;URL=delete.php\">";
And change: ( your_table ) and the id depending on which column you want to ORDER BY
$query = "select * from your_table ORDER BY id ASC";
And change:
$sql = "DELETE FROM your_table WHERE link_id='$del_id'";
And change: all instances of link_id being the id (column name) associated with the deletion.
Full script: (delete.php)
<html>
<head>
<title></title>
</head>
<body>
<h2>Choose and delete selected items.</h2>
<?php
DEFINE ('DB_HOST', 'xxx');
DEFINE ('DB_USER', 'xxx');
DEFINE ('DB_PASSWORD', 'xxx');
DEFINE ('DB_NAME', 'xxx');
$dbc = mysqli_connect (DB_HOST, DB_USER, DB_PASSWORD, DB_NAME)
OR die("could not connect");
$query = "select * from your_table ORDER BY id ASC";
$result = mysqli_query($dbc,$query)
or die('Error querying database');
$count=mysqli_num_rows($result);
?>
<table width="400" border="0" cellspacing="1" cellpadding="0">
<tr>
<td><form name="form1" method="post" action="">
<table width="400" border="0" cellpadding="3" cellspacing="1" bgcolor="#CCCCCC">
<tr>
<td bgcolor="#FFFFFF"> </td>
<td colspan="3" bgcolor="#FFFFFF"><strong>Delete multiple items</strong> </td>
</tr>
<tr>
<td align="center" bgcolor="#FFFFFF">#</td>
<td align="center" bgcolor="#FFFFFF"><strong>Link ID</strong></td>
<td align="center" bgcolor="#FFFFFF"><strong>Link Name</strong></td>
<td align="center" bgcolor="#FFFFFF"><strong>Link Email</strong></td>
</tr>
<?php
while ($row=mysqli_fetch_array($result)) {
?>
<tr>
<td align="center" bgcolor="#FFFFFF">
<input name="checkbox[]" type="checkbox" value="<?php echo $row['link_id']; ?>">
</td>
<td bgcolor="#FFFFFF"><?php echo $row['id']; ?></td>
<td bgcolor="#FFFFFF"><?php echo $row['name']; ?></td>
<td bgcolor="#FFFFFF"><?php echo $row['email']; ?></td>
</tr>
<?php
}
?>
<tr>
<td colspan="4" align="center" bgcolor="#FFFFFF"><input name="delete" type="submit" value="Delete"></td>
</tr>
<table width="400" border="0" cellspacing="1" cellpadding="0">
<tr>
<td><form name="form1" method="post" action="">
<table width="400" border="0" cellpadding="3" cellspacing="1" bgcolor="#CCCCCC">
<tr>
<td bgcolor="#FFFFFF"> </td>
<td colspan="3" bgcolor="#FFFFFF"><strong>Delete multiple items</strong> </td>
</tr>
<tr>
<td align="center" bgcolor="#FFFFFF">#</td>
<td align="center" bgcolor="#FFFFFF"><strong>Link ID</strong></td>
<td align="center" bgcolor="#FFFFFF"><strong>Link Name</strong></td>
<td align="center" bgcolor="#FFFFFF"><strong>Link Email</strong></td>
</tr>
<?php
while ($row=mysqli_fetch_array($result)) {
?>
<tr>
<td align="center" bgcolor="#FFFFFF">
<input name="checkbox[]" type="checkbox" value="<?php echo $row['link_id']; ?>">
</td>
<td bgcolor="#FFFFFF"><?php echo $row['id']; ?></td>
<td bgcolor="#FFFFFF"><?php echo $row['name']; ?></td>
<td bgcolor="#FFFFFF"><?php echo $row['email']; ?></td>
</tr>
<?php
}
?>
<tr>
<td colspan="4" align="center" bgcolor="#FFFFFF"><input name="delete" type="submit" value="Delete"></td>
</tr>
<?php
if(isset($_POST['delete']))
{
$checkbox = $_POST['checkbox'];
for($i=0;$i<count($checkbox);$i++){
$del_id = $checkbox[$i];
$sql = "DELETE FROM your_table WHERE link_id='$del_id'";
$result = mysqli_query($sql);
}
// if successful redirect to delete.php
if($result){
echo "<meta http-equiv=\"refresh\" content=\"3;URL=delete.php\">";
// echo "Got results.";
}
}
mysqli_close($dbc);
?>
</table>
</form>
</td>
</tr>
</table>
</body>
</html>

Answer 2

Try this:
if(isset($_POST['delete'])){
foreach($_POST['checkbox'] as $del_id){
$sql = "DELETE FROM Aktivitet WHERE Id_Akt='$del_id'";
$result = mysql_query($sql);
}
}