任何查询均需进入information_schema数据库，命令
use information_schema;
1，查看总数据量
select concat(round(sum(data_length/1024/1024),2),’MB’) as data from tables;
2，查看某个数据库的数据量，此处为data数据库
select concat(round(sum(data_length/1024/1024),2),’MB’) as data from tables where table_schema=’data’;
3，查看某个表的数据量，此处为data数据库中的storage表
select concat(round(sum(data_length/1024/1024),2),’MB’) as data from tables where table_schema=’data’ and table_name=’storage’;