CODEWITHSUNDEEP
phpmysql
demonoid
demonoid

Reputation: 326

Inserting values into multiple MySQL tables at once

I've created mini content management system. Now got afew questions

I'm filtering posts with following function 

function filter($data, $db)
{
    $data = trim(htmlentities(strip_tags($data)));
    if (get_magic_quotes_gpc())
    $data = stripslashes($data);
    $data = $db->escape_string($data);
    return $data;
}

And the PHP code looks like that

$name=filter($_POST['name'], $db);
$title=filter($_POST['title'], $db);
$parent=filter($_POST['parent'],$db);
$switch=filter($_POST['switch'], $db);
    if($switch=''){
        echo "Return back and select an option";
        die();
    }
$parentcheck=filter($_POST['parentcheck'],$db);
    if($parentcheck=='0')
    {
        $parent=$parentcheck;
    }   
$purifier = new HTMLPurifier();
$content = $db->real_escape_string( $purifier->purify( $_POST['content']) );

if(isset($_POST['submit'])&&$_POST['submit']=='Ok'){
    $result=$db->query("INSERT INTO menu (parent, name, showinmenu) VALUES ('$parent', '$name', '$switch'") or die($db->error);
    $result2=$db->query("INSERT INTO pages (id, title, content) VALUES ('<what?>', '$title', '$content'") or die($db->error);           
    }

And that's how my tables look like

Table named "pages" enter image description here

And "menu"

enter image description here

My questions are followings:

  1. I'm trying to get autoincremented id value from menu table after ('$parent', '$name', '$switch'") insertion and set this id in pages table while inserting ($title, $content). How to do it? Is it possible with single query?

  2. $content's value is the text with HTML tags. I'm using html purifier. May I filter it's value too before inserting into db table? Any suggestion/advice?

Upvotes: 0

Views: 1147

Answers (2)

Marc B
Marc B

Reputation: 360702

Looks like you're using mysqli as the DB library, so you can use $db->insert_id() to retrieve the LAST id created by an insert operation by that particular DB handle. So your queries would become:

$result=$db->query("INSERT INTO menu (parent, name, showinmenu) VALUES ('$parent', '$name', '$switch'") or die($db->error);
$new_id = $db->insert_id();
$result2=$db->query("INSERT INTO pages (id, title, content) VALUES ($new_id, '$title', '$content'") or die($db->error);           
                                                                    ^^^^^^^

You can't really do it in a single query, as mysql does not make the ID value available for the insert_id function until AFTER the query completes. So you do have to do this in a 3 step process: insert, get id, insert again.

The rule for DB filtering (better known as escaping) is to escape ANYTHING that's user-provided. This even includes data you've retrieve in other db queries and are re-inserting. Escaping isn't really there as a security measure - it's there to make sure that whatever you're putting into the query string doesn't BREAK the query. Preventing SQL injection attacks is just a side effect of this.

Upvotes: 1

Dominic
Dominic

Reputation: 806

Should be 

$result2=$db->query("INSERT INTO pages (id, title, content) VALUES (LAST_INSERT_ID(), '$title', '$content'") or die($db->error);

Filtering using real_escape_string( ) should be safe. Is there something else that you want to filter?

Upvotes: 1

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