Altering database size to add more space

[Sarkis Karayan]

I feel like I am missing something, because I am not able to find the
answer to this simple question.

How can I increase the size of a database?

I am using the following query to check the available space and notice
that it is time to increase.

SELECT
  table_schema AS 'Db Name',
  Round( Sum( data_length + index_length ) / 1024 / 1024, 3) AS 'Db Size (MB)',
  Round( Sum( data_free ) / 1024 / 1024, 3 ) AS 'Free Space (MB)'
FROM information_schema.tables
GROUP BY table_schema ;


Thank you.