How can I change the WordPress Custom Post & Categories to New Custom Post & Categories - sql

Question

In my database I have 2 custom post type and their category.
Old Post Type and Category
Post Type = real-estate
Category = re-category
Mew Post Type and Category
Post Type = real_estate
Category = real_estate_category
Now I want to convert all old post type and their categories to new custom post type and their categories.
So, using this code I can get all the old post type and can change the old post type to new post type BUT how can I change the old post type's attached categories to new post type categories?
add_action( 'template_redirect', 'everstrap_do_migration' );
function everstrap_do_migration() {
// Convert their real-estate to real_estate post type
if( $_REQUEST['action'] && $_REQUEST['action'] == 'convert_re_post_type' ) {
global $wpdb;
$old_custom_post_type = 'real-estate';
$ne_custom_post_type = 'real_estate';
// A sql query to return all real-esate post
$results = $wpdb->get_results( $wpdb->prepare( "SELECT ID, post_title FROM {$wpdb->posts} WHERE post_type = %s and post_status = 'publish'", $old_custom_post_type ), ARRAY_A );
// Return null if we found no results
if ( ! $results )
return;
foreach ( $result as $key => $value) {
// Update query
$update = $wpdb->update(
$wpdb->posts,
array(
'post_type' => $new_custom_post_type,
),
array(
'post_type' => $old_custom_post_type,
),
array(
'%s',
),
array(
'%s'
)
);
if( $update ) {
echo 'Updated post id ' . $value['ID'];
} else {
echo 'can\' update';
}
}
// echo '<pre>';
// print_r( $results );
// echo '</pre>';
}
}

Answer 1

$new = "real_estate_category";
$old = "re-category";
$cat = get_terms( array (
'taxonomy' => $old,
'hide_empty' => false,
));
global $wpdb;
$table = $wpdb->prefix . "term_taxonomy";
foreach ($cat as $c) {
$wpdb->update($table, array("taxonomy" => $new), array("term_id" => $c->term_id), array("%s"));
}