Human readable overview of MySQL/MariaDB database size

mysql-db-stats.sql

SELECT table_schema                                              "Database", 
  Round(Sum(data_length)                / 1024 / 1024, 0)        "Data size (in MB)",
  Round(Sum(data_length)                / 1024 / 1024 / 1024, 3) "Data size (in GB)",
  Round(Sum(index_length)               / 1024 / 1024, 0)        "Index size (in MB)",
  Round(Sum(index_length)               / 1024 / 1024 / 1024, 3) "Index size (in GB)",
  Round(Sum(data_length + index_length) / 1024 / 1024, 0)        "Total size (in MB)",
  Round(Sum(data_length + index_length) / 1024 / 1024 / 1024, 3) "Total size (in GB)"
FROM information_schema.tables 
GROUP BY table_schema;