查看所有数据库大小

select table_schema, concat(truncate(sum(data_length)/1024/1024,2),' mb') as data_size,
concat(truncate(sum(index_length)/1024/1024,2),'mb') as index_size
from information_schema.tables
group by table_schema
order by data_size desc;

查看当前某个数据库和数据库下所有的表的大小

select table_schema, concat(truncate(sum(data_length)/1024/1024,2),' mb') as data_size,
concat(truncate(sum(index_length)/1024/1024,2),'mb') as index_size
from information_schema.tables where table_schema = 'mysql' 
group by table_schema
order by data_size desc;