转自 https://www.cnblogs.com/shoshana-kong/p/11136919.html

前言：在mysql中有一个默认的数据表information_schema，information_schema这张数据表保存了MySQL服务器所有数据库的信息。如数据库名，数据库的表，表栏的数据类型与访问权限等。再简单点，这台MySQL服务器上，到底有哪些数据库、各个数据库有哪些表，每张表的字段类型是什么，各个数据库要什么权限才能访问，等等信息都保存在information_schema表里面，所以请勿删改此表。

代码：

1，切换数据库

use information_schema;

2，查看数据库使用大小

select concat(round(sum(data_length/1024/1024),2),’MB’) as data from tables where table_schema=’DB_Name’ ;

3，查看表使用大小

select concat(round(sum(data_length/1024/1024),2),’MB’) as data from tables where table_schema=’DB_Name’ and table_name=’Table_Name’;

 -----------------------------------------------------------------------------------

网上找的一个，亲测可用:

//先进去MySQL自带管理库：information_schema  
//然后查询 data_length,index_length
//你自己的数据库名：dbname   
//你自己的表名：tablename  
  
mysql> use information_schema;  
Database changed  
mysql> select data_length,index_length  
    -> from tables where  
    -> table_schema='dbname'  
    -> and table_name = 'tablename';  
+-------------+--------------+  
| data_length | index_length |  
+-------------+--------------+  
|   166379520 |    235782144 |  
+-------------+--------------+  
row in set (0.02 sec)  
  
mysql> select concat(round(sum(data_length/1024/1024),2),'MB') as data_length_MB,  
    -> concat(round(sum(index_length/1024/1024),2),'MB') as index_length_MB  
    -> from tables where  
    -> table_schema='dbname'  
    -> and table_name = 'tablename';  
+----------------+-----------------+  
| data_length_MB | index_length_MB |  
+----------------+-----------------+  
| 158.67MB       | 224.86MB        |  
+----------------+-----------------+  
row in set (0.03 sec)

 -----------------------------------------------------------------------------------

1.查看所有数据库容量大小

2.查看所有数据库各表容量大小

3.查看指定数据库容量大小

例：查看mysql库容量大小

4.查看指定数据库各表容量大小

例：查看mysql库各表容量大小

select concat(round(sum(data_length/1024/1024),2),'MB') as data_length_MB, concat(round(sum(index_length/1024/1024),2),'MB') as index_length_MB
from tables 
where table_schema='passport' and table_name='tb_user_info';
-- 569.98MB 141.98MB

select concat(round(sum(data_length/1024/1024),2),'MB') as data_length_MB, concat(round(sum(index_length/1024/1024),2),'MB') as index_length_MB
from tables
where table_schema='passport_v2' and table_name='tb_user_info';

--   2128.94MB   285.00MB