SELECT table_schema AS "Database",
ROUND(SUM(data_length + index_length) / 1024 / 1024, 2) AS "Size (MB)"
FROM information_schema.TABLES
GROUP BY table_schema;
+--------------------+-----------+
| Database | Size (MB) |
+--------------------+-----------+
| information_schema | 0.07 |
| mysql | 0.63 |
| performance_schema | 0.00 |
| zabbix | 38817.25 |
+--------------------+-----------+
4 rows in set (0.54 sec)