1 命令行进入数据库

[root@80 ~]# mysql -uroot -p
Enter password:

2 查看数据库

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| test               |
+--------------------+

3 查看information_schema的"TABLES"

mysql> use information_schema;
| TABLES                                |

4 查看字段结构

mysql> desc tables;
+-----------------+---------------------+------+-----+---------+-------+
| Field           | Type                | Null | Key | Default | Extra |
+-----------------+---------------------+------+-----+---------+-------+
| TABLE_CATALOG   | varchar(512)        | NO   |     |         |       |
| TABLE_SCHEMA    | varchar(64)         | NO   |     |         |       |
| TABLE_NAME      | varchar(64)         | NO   |     |         |       |
| TABLE_TYPE      | varchar(64)         | NO   |     |         |       |
| ENGINE          | varchar(64)         | YES  |     | NULL    |       |
| VERSION         | bigint(21) unsigned | YES  |     | NULL    |       |
| ROW_FORMAT      | varchar(10)         | YES  |     | NULL    |       |
| TABLE_ROWS      | bigint(21) unsigned | YES  |     | NULL    |       |
| AVG_ROW_LENGTH  | bigint(21) unsigned | YES  |     | NULL    |       |
| DATA_LENGTH     | bigint(21) unsigned | YES  |     | NULL    |       |
| MAX_DATA_LENGTH | bigint(21) unsigned | YES  |     | NULL    |       |
| INDEX_LENGTH    | bigint(21) unsigned | YES  |     | NULL    |       |
| DATA_FREE       | bigint(21) unsigned | YES  |     | NULL    |       |
| AUTO_INCREMENT  | bigint(21) unsigned | YES  |     | NULL    |       |
| CREATE_TIME     | datetime            | YES  |     | NULL    |       |
| UPDATE_TIME     | datetime            | YES  |     | NULL    |       |
| CHECK_TIME      | datetime            | YES  |     | NULL    |       |
| TABLE_COLLATION | varchar(32)         | YES  |     | NULL    |       |
| CHECKSUM        | bigint(21) unsigned | YES  |     | NULL    |       |
| CREATE_OPTIONS  | varchar(255)        | YES  |     | NULL    |       |
| TABLE_COMMENT   | varchar(2048)       | NO   |     |         |       |
+-----------------+---------------------+------+-----+---------+-------+

5 查看DB的数据大小

mysql> select table_schema,round(sum(DATA_LENGTH)/1024/1024,2) as table_size from tables group by table_schema;
+--------------------+------------+
| table_schema       | table_size |
+--------------------+------------+
| bomo_backend       |       0.09 |
| test1              |     234.16 |
| test2              |       0.17 |
| information_schema |       0.00 |
| mysql              |       0.71 |
| performance_schema |       0.00 |
| test               |       0.03 |
+--------------------+------------+

6 查看table的数据大小

mysql> select table_schema,table_name,concat(round(data_length/1024/1024,2),'M') as table_size from tables where table_schema = 'grab';
+--------------+--------------+------------+
| table_schema | table_name   | table_size |
+--------------+--------------+------------+
| grab         | product      | 215.12M    |
| grab         | result       | 13.52M     |
| grab         | rule         | 0.02M      |
| grab         | task         | 5.52M      |
+--------------+--------------+------------+