jQuery Datatables : Searching and filtering with Ajax pagination
You will have to do all the searching & filtering on server side.
For every request of search/filter or page, the datatable passes all of this as form data to the server page. Refer https://www.datatables.net/manual/server-side
You will have to use this form data to filter/search/paginate on the records on sql table & pass it accordingly to the client.
The datatable merely shows what it gets from the server.