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';

查询某个库中所有表的大小:

select TABLE_NAME, concat(truncate(data_length/1024/1024,2),' MB') as data_size,  

concat(truncate(index_length/1024/1024,2),' MB') as index_size  

from information_schema.tables where TABLE_SCHEMA = 'DATABASE_NAME'  

group by TABLE_NAME  

order by data_length desc;