为什么使用Nginx配置alias别名访问phpmyadmin会导致文件下载而不是正常显示？

  # 使用/mysql别名访问phpmyadmin
  location ^~ /mysql {
    alias /home/wwwroot/default/phpmyadmin/;
    index index.php;
  }

  # 处理php文件，但仍然导致文件下载
  location ~ /mysql/.+\.php$ {
      if ($fastcgi_script_name ~ /mysql/(.+\.php.*)$) {
          set $valid_fastcgi_script_name $1;
      }
      include fastcgi_params;
      fastcgi_pass 127.0.0.1:9000;
      fastcgi_index index.php;
      fastcgi_param SCRIPT_FILENAME /home/wwwroot/default/phpmyadmin/$valid_fastcgi_script_name;
  }

  location ~ \.php(.*)$ {
        fastcgi_pass   127.0.0.1:9000;
        fastcgi_index  index.php;
        fastcgi_split_path_info  ^((?U).+\.php)(/?.+)$;
        fastcgi_param  SCRIPT_FILENAME  $document_root$fastcgi_script_name;
        fastcgi_param  PATH_INFO  $fastcgi_path_info;
        fastcgi_param  PATH_TRANSLATED  $document_root$fastcgi_path_info;
        include        fastcgi_params;
  }