Hi ,
im new to dhtmlx api and learning to use the Scheduler for php and i was wondering if it’s possible to not use the DataProcessor and DataConnector for crud operations ?
if no , what is the best way to handle crud operations for multiple tables using (ajax calls / json) ?
Thank you 
Sure, you can use your own backend. Scheduler provides a lot of events for data adding|editing|deleting from which you can call your own scripts by ajax or use any other logic to save the changes.
Also, you can use Connector but use server-side events to override default logic. ( in such case connector will work just as a data protocol handler, and all DB logic will be handled with your scripts )