Requête
SELECT table_schema AS "Database name", SUM(data_length + index_length) / 1024 / 1024 AS "Size (MB)" FROM information_schema.TABLES GROUP BY table_schema
Résultat
+--------------------+--------------+ | Database name | Size (MB) | +--------------------+--------------+ | database 1 | 607.70312500 | | database 2 | 647.92187500 | | information_schema | 0.00878906 | | database 3 | 417.16526890 | | database 4 | 567.17187500 | +--------------------+--------------+