WooCommerce Search by SKU

gistfile1.txt

add_filter( 'posts_where', 'search_by_sku' );

function search_by_sku( $where ) {
  if( ! is_search() ) {
    return $where;
  }
  
  global $wpdb;
    
  $query = get_search_query();
  $query = $wpdb->esc_like( $query );

  $where .=" OR {$wpdb->posts}.ID IN (SELECT IF({$wpdb->posts}.post_parent>0,{$wpdb->posts}.post_parent,{$wpdb->posts}.ID) FROM {$wpdb->posts}, {$wpdb->postmeta} WHERE {$wpdb->postmeta}.meta_key = '_sku' AND {$wpdb->postmeta}.meta_value LIKE '%$query%' AND {$wpdb->posts}.ID = {$wpdb->postmeta}.post_id)";

  return $where;
}