mysql> use information_schema ; /*切换到information_schema数据下*/
Database changed
mysql>
mysql> select concat(round(sum(data_length/1024/1024),2),'MB') as data from tables; /*查询所有数据大小*/
+----------+
| data |
+----------+
| 123.68MB |
+----------+
1 row in set (0.36 sec)
mysql> select concat(round(sum(data_length/1024/1024),2),'MB') as data from tables where table_schema='hrkip'; /*查询数据库名称为“hrkip”的数据大小*/
+--------+
| data |
+--------+
| 8.65MB |
+--------+
1 row in set (0.00 sec)
mysql> select concat(round(sum(data_length/1024/1024),2),'MB') as data from tables where table_schema='hrkip' and table_name='jx_lsjl' ; /*查询数据库名称为“hrkip”，表名为“ jx_lsjl”的数据大小*/
+--------+
| data |
+--------+
| 6.77MB |
+--------+
1 row in set (0.00 sec)
备注 ：
data_length ：存储数据大小
data_length/1024/1024：将字节转换为MB
round(sum(data_length/1024/1024),2)：取两位小数
concat(round(sum(data_length/1024/1024),2),'MB') ：给计算结果追加单位 “MB”