Question

I am trying very hard for the last 2 hours but am not able to understand. Why am I getting undefined variable in DELETE. Please please look in to my code and help me out.

My main intention is to delete multiple rows at once using checkboxes.

When I am trying to run the below codes it gives me following errors:

Undefined variable: delete in C:\xampp\htdocs\xampp\Test\HRMS\try\search1.php on line 61

But I already have used it in following way:

<td colspan="5" align="center" bgcolor="#FFFFFF"><input name="delete" type="submit" id="delete" value="Delete"></td>

Thanks in advance.

my php codes :

  <?php
  $host="localhost"; // Host name
  $username="a"; // Mysql username
  $password="a"; // Mysql password
  $db_name="b"; // Database name
  $tbl_name="emp_info"; // Table name

  // Connect to server and select databse.
  mysql_connect("$host", "$username", "$password")or die("cannot connect");
  mysql_select_db("$db_name")or die("cannot select DB");

  $sql="SELECT * FROM $tbl_name";
  $result=mysql_query($sql);

  $count=mysql_num_rows($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">&nbsp;</td>
  <td colspan="4" bgcolor="#FFFFFF"><strong>Delete multiple rows in mysql</strong> </td>
  </tr>
  <tr>
  <td align="center" bgcolor="#FFFFFF">#</td>
  <td align="center" bgcolor="#FFFFFF"><strong>Id</strong></td>
  <td align="center" bgcolor="#FFFFFF"><strong>Name</strong></td>
  <td align="center" bgcolor="#FFFFFF"><strong>Password</strong></td>
  <td align="center" bgcolor="#FFFFFF"><strong>Address</strong></td>
  <td align="center" bgcolor="#FFFFFF"><strong>Source</strong></td>
  <td align="center" bgcolor="#FFFFFF"><strong>salary</strong></td>
  <td align="center" bgcolor="#FFFFFF"><strong>Zip</strong></td>
  <td align="center" bgcolor="#FFFFFF"><strong>Mobile</strong></td>
  <td align="center" bgcolor="#FFFFFF"><strong>Email</strong></td>
  </tr>
  <?php
  while($rows=mysql_fetch_array($result)){
  ?>
  <tr>
  <td align="center" bgcolor="#FFFFFF"><input name="checkbox[]" type="checkbox" id="checkbox[]" value="<? echo $rows['eid']; ?>"></td>
  <td bgcolor="#FFFFFF"><? echo $rows['eid']; ?></td>
  <td bgcolor="#FFFFFF"><? echo $rows['ename']; ?></td>
  <td bgcolor="#FFFFFF"><? echo $rows['password']; ?></td>
  <td bgcolor="#FFFFFF"><? echo $rows['address']; ?></td>
  <td bgcolor="#FFFFFF"><? echo $rows['source']; ?></td>
  <td bgcolor="#FFFFFF"><? echo $rows['salary']; ?></td>
  <td bgcolor="#FFFFFF"><? echo $rows['zip']; ?></td>
  <td bgcolor="#FFFFFF"><? echo $rows['mobile']; ?></td>
  <td bgcolor="#FFFFFF"><? echo $rows['email']; ?></td>
  </tr>
  <?php
  }
  ?>
  <tr>
  <td colspan="5" align="center" bgcolor="#FFFFFF"><input name="delete" type="submit" id="delete" value="Delete"></td>
  </tr>
  <?php
  // Check if delete button active, start this
  if($delete){
  for($i=0;$i<$count;$i++){
  $del_id = $checkbox[$i];
  $sql = "DELETE FROM $tbl_name WHERE eid='$del_id'";
  $result = mysql_query($sql);
  }

  // if successful redirect to search1.php
  if($result){
  echo "<meta http-equiv=\"refresh\" content=\"0;URL=search1.php\">";
  }
  }
  mysql_close();
  ?>
  </table>
  </form>
  </td>
  </tr>
  </table>

Answer 1

Before looping results from MySQL result variable, you should ALWAYS have to make sure that it contain any values:

if($total > 0)
{
    while ($rows = mysql_fetch_array($result))
    {
        //your code goes here
    }
}

Another issue you have here, is same as in your previous question, variable $delete is not defined, based on your code, it is not clear where it is coming from.

So, if $delete is actually a $_POST variable, your if statement should look like this:

if(isset($_POST['delete'])){}

Another issue, $checkbox it is not defined to. I would recommend you to read more about filter_input method as it can be very handy on sanitizing user submitted data.

Also you are using incorrect html tags instead of:

<td align="center" bgcolor="#FFFFFF"><strong>Id</strong></td>

use correct TD tag which aligns text in center and makes it bold, also bgcolor should be defined in CSS file.

<th bgcolor="#FFFFFF">Id</th>

Your final code should look like this:

<?php
$host = "localhost"; // Host name
$username = "a"; // Mysql username
$password = "a"; // Mysql password
$db_name = "b"; // Database name
$tbl_name = "emp_info"; // Table name

// Connect to server and select databse.
mysql_connect("$host", "$username", "$password")or die("cannot connect");
mysql_select_db("$db_name")or die("cannot select DB");

// Make sure that delete action was called using
//$delete = isset($_POST['delete']);
//OR
//$delete = array_key_exists('delete', $_POST);
//OR
$delete = filter_input(INPUT_POST, 'delete');

$selected = filter_input(INPUT_POST, 'checkbox', FILTER_VALIDATE_INT, FILTER_REQUIRE_ARRAY);

if ($delete && !empty($selected))
{

    foreach ($selected as $id)
    {
        $sql = "DELETE FROM $tbl_name WHERE eid='$id'";

        $result = mysql_query($sql);
    }

    // if successful redirect to search1.php
    echo "<meta http-equiv=\"refresh\" content=\"0;URL=search1.php\">";
}

$sql = "SELECT * FROM $tbl_name";

$result = mysql_query($sql);

$count = mysql_num_rows($result);

?>


<form name="form1" method="post" action="">
    <table width="400" border="0" cellpadding="3" cellspacing="1" bgcolor="#CCCCCC">
        <tr>
            <th bgcolor="#FFFFFF">&nbsp;</th>
            <th colspan="9" bgcolor="#FFFFFF">Delete multiple rows in mysql</th>
        </tr>
        <tr>
            <th bgcolor="#FFFFFF">#</th>
            <th bgcolor="#FFFFFF">Id</th>
            <th bgcolor="#FFFFFF">Name</th>
            <th bgcolor="#FFFFFF">Password</th>
            <th bgcolor="#FFFFFF">Address</th>
            <th bgcolor="#FFFFFF">Source</th>
            <th bgcolor="#FFFFFF">salary</th>
            <th bgcolor="#FFFFFF">Zip</th>
            <th bgcolor="#FFFFFF">Mobile</th>
            <th bgcolor="#FFFFFF">Email</th>
        </tr>
        <?php
        if ($count)
        {
            while ($rows = mysql_fetch_array($result))
            {
                ?>
                <tr>
                    <td align="center" bgcolor="#FFFFFF">
                        <input name="checkbox[]" type="checkbox" id="checkbox" value="<?php echo $rows['eid']; ?>">
                    </td>
                    <td bgcolor="#FFFFFF"><?php echo $rows['eid']; ?></td>
                    <td bgcolor="#FFFFFF"><?php echo $rows['ename']; ?></td>
                    <td bgcolor="#FFFFFF"><?php echo $rows['password']; ?></td>
                    <td bgcolor="#FFFFFF"><?php echo $rows['address']; ?></td>
                    <td bgcolor="#FFFFFF"><?php echo $rows['source']; ?></td>
                    <td bgcolor="#FFFFFF"><?php echo $rows['salary']; ?></td>
                    <td bgcolor="#FFFFFF"><?php echo $rows['zip']; ?></td>
                    <td bgcolor="#FFFFFF"><?php echo $rows['mobile']; ?></td>
                    <td bgcolor="#FFFFFF"><?php echo $rows['email']; ?></td>
                </tr>
                <?php
            }
        }
        mysql_close();
        ?>
        <tr>
            <td colspan="10" align="center" bgcolor="#FFFFFF">
                <input name="delete" type="submit" id="delete" value="Delete">
            </td>
        </tr>
    </table>
</form>

Please don’t just copy paste it, read it and try to understand it.