Bulk add tag (or any sort of label) to posts who have custom excerpt

Some questions are easily solved searching this Stack and joining some answers together.

• Bulk post type conversion
• Automated adding of one tag to all the posts in a category

The following plugin will run the conversion code when activated. Adjust the $tags array, and don’t forget to backup your database before proceeding.

<?php
/* Plugin Name: Remove Excerpts, Add Tags */

register_activation_hook( __FILE__, 'wpse_56133_add_tags_remove_excerpts' );    

function wpse_56133_add_tags_remove_excerpts() {
    $tags = array( 'YOUR TAG NAME A HERE', 'YOUR TAG NAME B HERE' );

    $args = array( 'post_type' => 'post', 'numberposts' => -1, 'post_status' => published );
    $posts = get_posts( $args );
    foreach ( $posts as $post )
    {
        $po = array();
        $po = get_post( $post->ID,'ARRAY_A' );
        $po['post_excerpt'] = "";
        wp_update_post( $po );

        //set last value to false if you want to replace existing tags.
        wp_set_post_terms( intval( $post->ID ), $tags, 'post_tag', true ); 
    }
}