Try to bulk update label name in catalog_product_entity_media_gallery_value,
CSV formate :
Workout:
<?php
require_once 'app/Mage.php';
umask("0");
Mage::app();
ini_set('display_errors',"1");
ini_set('display_startup_errors', "1");
error_reporting(E_ALL);
if (($handle = fopen("inputs.csv", "r")) !== FALSE)
{
while (($data = fgetcsv($handle, '1000', ",")) !== FALSE)
{
$sql='UPDATE catalog_product_entity_media_gallery_value SET label='.$data['2'].' WHERE value_id = '.$data['0'].'';
echo $sql.'<br/>';
mysqli_query($sql);
}
fclose($handle);
}
?>
How to alter my script for Magento 1.9?