Query to retrieve MySQL database size

If you need to determine how much data a MySQL database is consuming, use the information_schema database and run the following command:
mysql> use information_schema;
mysql> select table_schema, sum(data_length)/1024/1024 from tables group by table_schema;
+----------------------------+-----------------------------------------+
| table_schema | sum(data_length)/1024/1024 |
+----------------------------+-----------------------------------------+
| information_schema | 0.00000000 |
| mysql | 0.41797256 |
| uptime | 4031.60937500 |
+----------------------------+-----------------------------------------+
3 rows in set (1.04 sec)
In the example above, Uptime Infrastructure Monitor is using ~ 4.03 GB.