mysql中如何查看某个数据库或表占用的磁盘空间

查整个库的状态：
select concat(truncate(sum(data_length)/1024/1024,2),'MB') as data_size,
          concat(truncate(sum(max_data_length)/1024/1024,2),'MB') as max_data_size,
          concat(truncate(sum(data_free)/1024/1024,2),'MB') as data_free,
          concat(truncate(sum(index_length)/1024/1024,2),'MB') as index_size
  from information_schema.tables
where TABLE_SCHEMA = 'databasename';

查单表：
select concat(truncate(sum(data_length)/1024/1024,2),'MB') as data_size,
          concat(truncate(sum(max_data_length)/1024/1024,2),'MB') as max_data_size,
          concat(truncate(sum(data_free)/1024/1024,2),'MB') as data_free,
          concat(truncate(sum(index_length)/1024/1024,2),'MB') as index_size
  from information_schema.tables
where TABLE_NAME = 'tablename';

链接：http://wwwdd2315.blog.163.com/blog/static/66661889201182710429124/

http://www.oschina.net/question/12_3673