进入终端

mysql -uroot -p
show databases;
use information_schema;

1.查看数据库总大小

select concat(round(sum(DATA_LENGTH/1024/1024),2),'MB') as data from tables;

2.查询某个数据库的大小

select concat(round(sum(DATA_LENGTH/1024/1024),2),'MB') as data from tables where TABLE_SCHEMA='wordpress';

3.查询某个数据库下某个表的大小

select concat(round(DATA_LENGTH/1024/1024,2),'MB') as data from tables where TABLE_SCHEMA='wordpress' and TABLE_NAME='wp_options';