第一种情况：查询所有数据库的总大小，方法如下：

mysql> use information_schema;

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

+-----------+

| data      |

+-----------+

| 3052.76MB |

+-----------+

1 row in set (0.02 sec)

统计一下所有库数据量

每张表数据量=AVG_ROW_LENGTH*TABLE_ROWS+INDEX_LENGTH

SELECT

SUM(AVG_ROW_LENGTH*TABLE_ROWS+INDEX_LENGTH)/1024/1024 AS total_mb

FROM information_schema.TABLES

统计每个库大小：

SELECT

table_schema,SUM(AVG_ROW_LENGTH*TABLE_ROWS+INDEX_LENGTH)/1024/1024 AS total_mb

FROM information_schema.TABLES group by table_schema;

第二种情况：查看指定数据库的大小，比如说：数据库test，方法如下：

mysql> use information_schema;

mysql> select concat(round(sum(DATA_LENGTH/1024/1024),2),'MB') as data from TABLES where table_schema='test';

+----------+

| data     |

+----------+

| 142.84MB |

+----------+

1 row in set (0.00 sec)

1.查看所有数据库各容量大小

select

table_schema as '数据库',

sum(table_rows) as '记录数',

sum(truncate(data_length/1024/1024, 2)) as '数据容量(MB)',

sum(truncate(index_length/1024/1024, 2)) as '索引容量(MB)'

from information_schema.tables

group by table_schema

order by sum(data_length) desc, sum(index_length) desc;

2.查看所有数据库各表容量大小

select

table_schema as '数据库',

table_name as '表名',

table_rows as '记录数',

truncate(data_length/1024/1024, 2) as '数据容量(MB)',

truncate(index_length/1024/1024, 2) as '索引容量(MB)'

from information_schema.tables

order by data_length desc, index_length desc;

3.查看指定数据库容量大小

例：查看mysql库容量大小

select

table_schema as '数据库',

sum(table_rows) as '记录数',

sum(truncate(data_length/1024/1024, 2)) as '数据容量(MB)',

sum(truncate(index_length/1024/1024, 2)) as '索引容量(MB)'

from information_schema.tables

where table_schema='mysql';

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

table_schema as '数据库',

table_name as '表名',

table_rows as '记录数',

truncate(data_length/1024/1024, 2) as '数据容量(MB)',

truncate(index_length/1024/1024, 2) as '索引容量(MB)'

from information_schema.tables

where table_schema='mysql'

order by data_length desc, index_length desc;