note when saving data from $_POST in wordpress (wp_magic_quotes).

avoid-slashes-when-saving.md

Because wordpress call wp_magic_quotes() to add slashes before we use $_POST or $_GET ($_REQUEST), so if you save data from $_POST or $_GET ($_REQUEST) in wordpress,

• single value, do

$username = stripslashes($_POST['username'])

• or all of values, do

$_POST = stripslashes_deep($_POST);

before calling $wpdb->insert()