i want to Delete where id=$POST['id'] in php mysql

Question

My code for delete entry is this but its not doing anything

HTML

<form id="form3" name="form3" method="post" onsubmit="return validateForm();" action="">
    Id <input type="text" class="txt" name="id" /><br />
    <input type="submit" id="delete" value="delete"/>
</form>

PHP

global $wpdb;

if ( isset ( $_POST['id'] ) && ! empty ( $_POST['id']  ))
{
    $wpdb->query("DELETE " . PRO_TABLE_PREFIX . "tutorial  WHERE id='{$_POST['id']}'");
}

Answer 1

那就是我通常的做法：

$wpdb->query("DELETE " . PRO_TABLE_PREFIX . "tutorial  WHERE id='".$_POST['id']."')

Answer 2

In oder to avoid confusion like this, I always use sprintf() where I need to concatenate strings

Change:

global $wpdb;
if ( isset ( $_POST['id'] ) && ! empty ( $_POST['id']  )) {
    $wpdb->query("DELETE " . PRO_TABLE_PREFIX . "tutorial  WHERE id='{$_POST['id']}'");
}

to:

global $wpdb;

if ( isset ( $_POST['id'] ) )) {    

   $wpdb->query(sprintf("DELETE %stutorial  WHERE id='%s'", PRO_TABLE_PREFIX, $_POST['id']));
}

A couple of things to note:

1) You're vulnerable to SQL injection
2) Once you've used isset() to determine if the key of $_POST['id'] actually isn't NULL , you don't need to check if its empty via empty()

Update

You should really test $_POST['id'] if its valid. I'd suggest you to implement a function, like, is_id_valid()

function is_id_valid(&$id){ //<-- IMPORTANT, Argument should be a reference 

  if ( ! isset($id) ){
     return false;
  }

  if ( empty($id) ){
    return false;
  }

  // add this if you expect $id to be a numeric value
  // otherwise just ignore - do not add
  if ( ! is_numeric($id) ){
    return false;  
  }

  //it's also a good to validate the length 
  if ( strlen($id) > ... && strlen($id) < ... ){
     return false;
  } 

  //seems like all tests passed
  return true;
}

Then you would use it, like

if ( is_id_valid($_POST['id']) !== false ){
   ....
}

Warning: It's still vulnerably to SQL injection

Answer 3

Remove single quote around post['id'] :

$wpdb->query("DELETE " . PRO_TABLE_PREFIX . "tutorial  WHERE id={$_POST['id']}")

OR

echo $query = "DELETE " . PRO_TABLE_PREFIX . " tutorial  WHERE id =".mysql_real_escape_string($_POST['id']);
$wbpd->query($query);

Answer 4

$wpdb->query("DELETE FROM " . PRO_TABLE_PREFIX . "tutorial  WHERE id='{$_POST['id']}'");

PS: Go overthere and accept one answer who helped you most. And here too! :P

Answer 5

Try following code:-

global $wpdb;

if ( isset ( $_POST['id'] ) && ! empty ( $_POST['id']  ))
{
$wpdb->query("DELETE FROM " . PRO_TABLE_PREFIX . "tutorial  WHERE id=".$_POST['id']);
}

Answer 6

give some action path to the form 

html

<form id="form3" name="form3" method="post" onsubmit="return validateForm();" action="give some actions">
Id <input type="text" class="txt" name="id" /><br />
<input type="submit" id="delete" value="delete"/>

php

global $wpdb;

if ( isset ( $_POST['id'] ) && ! empty ( $_POST['id']  ))
{
  $id=stripslashes_deep($_POST['id']);
  $wpdb->query("DELETE FROM " . PRO_TABLE_PREFIX . "tutorial  WHERE id=$id");
}

Answer 7

Since you are checking for id in WHERE clause, you need not wrap it in quotes, and you are missing FROM in your delete statement, so standard way would be: And do some filtering of POST data before inserting into database , like doing:

$id = (int) $_POST['id'];
if( $id > 0 ) {
    $wpdb->query("DELETE FROM " . PRO_TABLE_PREFIX . "tutorial  WHERE id=".$_POST['id']);
}