wordpress底部的版权日期如何实现每年自动更新

每个网站底部都会出现一个版权日期，比如web建站建站的版权日期是Copyright©2019-2023，那么如何实现每年自动更新呢？

找到当前主题函数模板functions.php中新增以下代码：

function ipkd_copyright() {
  global $wpdb;
  $copyright_dates = $wpdb->get_results("SELECT YEAR(min(post_date_gmt)) AS firstdate, YEAR(max(post_date_gmt)) AS lastdate FROM $wpdb->posts WHERE post_status = 'publish'");
  $output = '';
  if( $copyright_dates ) {
    $copyright = "© " . $copyright_dates[0]->firstdate;
    if( $copyright_dates[0]->firstdate != $copyright_dates[0]->lastdate ) {
      $copyright .= '-' . $copyright_dates[0]->lastdate;
    }
    $output = $copyright;
  }
  return $output;
}

在页面中调用一以下代码：

<?php echo ipkd_copyright(); ?>