I am the maintainer of Charts, and it's definitely designed for plotting data stored in your database. I recommend using Views. This is a good tutorial: https://www.ostraining.com/blog/drupal/create-charts-with-views/
[The documentation page on Drupal.org seems to have some broken link issues - I will work to fix this].
If you want to plot data in a non-...
The complete answer above did not work for me, be gave me the clue to look for the storage formats.
My date was a DATE format (and note DATETIME as in the given example), so just use the right constant.
constant DATETIME_STORAGE_FORMAT :: string(12) "Y-m-d\TH:i:s"
constant DATE_STORAGE_FORMAT :: string(5) "Y-m-d"
$dtime = DateTime::...
hook_schema() is only used to return a structured array representing your module's database tables. You can't execute a query from it. Well, you physically can, but you shouldn't.
Since hook_schema() is used on install, your code to create the View should be in hook_install(), and the code to remove it should be in hook_uninstall()
You can try login with https://drushcommands.com/drush-8x/user/user-login/
drush uli admin
Which will give you a login link for user admin
If you invoke it without a username it gives you a login link for user 1
Up-to-date method for Drupal 8 (for field name "field_myfield"):
Edit structure for table node__field_myfield, set new length for column field_myfield_value.
Edit structure for table node_revision__field_myfield, set new length for column field_myfield_value.
Use Admin Toolbar Extra Tools module, top menu: go to Development > Config editor
Yes. MySQL 5.7 is compatible with D7.x. Per the docs:
Drupal 7 supports MySQL 5.0.15/MySQL 5.1.30/MariaDB 5.1.44/Percona
Server 5.1.70 or higher, and requires the PDO database extension for
PHP (see What is PDO?).
Is it safe? Maybe. It depends on your code/infrastructure setup.
Just because a web application is compatible with a version of a DB ...
As solution for site structure I use config synchronization, which is in Drupal 8 Core, and I use it with drush commands ("cex" - configuration export and "cim" - configuration import).
For content sync I don't have much experience, but I saw new module that can be interesting solution: https://www.drupal.org/project/content_sync.
You're including the primary key as a field, which won't work. It needs to be on the same level as fields:
'fields' => [
'id' => [
'description' => 'The ID of the database entry of bar.',
'type' => 'serial',
'primary key' => ['id'],
Yes, with caveats that your DB infrastructure config will dictate if you can do this.
While MySQL allows you to do cross DB table joins, the DB user needs privileges to access both DB's to do it. Additionally, Drupal can only use one DB connection to execute a cross DB table join query.
So if you had a connection defined in your settings.php, called ...