Text Ad is defined with the wrong Field Type

Where do we put this code, the 255 limit is really hard to use HTML in.

So, would it be possible, to construct that for me. I have yet to create a module to have that ... Do I just take that script in #2 and put it into a function?

Up added this to _7006 update in the simpleads.update.inc file.
I can see in the DB that the fields are now long text fields, but Drupal is still reporting that there is a text character limit of 255.

I had a look in the field_config table and field_text_ad is set to type:text and module: text
I changed that to type:text_long, and then manual cleared flushed caches.
Still nothing. What am I missing? I tried to run the field_cache_clear(); again, but it didn't seem like that helped.
Here is what I added to the update file

function simpleads_update_7007(&$sandbox) {

$fieldInfo = field_info_field("field_ad_text");
$fieldInfoID = $fieldInfo['id'];
/**
 * Collect the field configuration
 */
$q = <<<SQL
SELECT `data`
FROM `field_config`
WHERE `id`=$fieldInfoID
SQL;
$res = db_select('field_config', 'c')
    ->fields('c', array('data'))
    ->condition('id', $fieldInfoID)
    ->execute()
    ->fetchAssoc();
$data = $res['data'];
$dataA = unserialize($data);
$dataA['settings'] = array();
if (1 > $dataA['settings']) {
    // the field configuration is wrong; correct the configuration
    $data = serialize($dataA);
    $q = <<<SQL
UPDATE `field_config`
SET `type`=:type, `data`=:data
WHERE `id`=$fieldInfoID
SQL;
    db_query($q, array(':type' => "text_long", ':data' => $data));
    /**
     * Correct field_ad_text column definition
     */
    $dbs = array('field_data_field_ad_text', 'field_revision_field_ad_text');
    foreach ($dbs as $db) {
        $q = <<<SQL
ALTER TABLE `$db`
CHANGE `field_ad_text_value` `field_ad_text_value` LONGTEXT
SQL;
        db_query($q);
    }
    /**
     * Clear the cache so our new settings take effect
     */
    field_cache_clear();
}


}