Method: Returns an array of products belonging to given categories.

Method: Get WHERE filter by object ids subquery.

Method: Returns an array of ids of allowed products, based on query arguments from the user.

Method: Returns comma separated ids of allowed products, based on query arguments from the user.

Method: Returns comma separated ids of allowed variations, based on query arguments from the user.

Method: Updates start and end dates for intervals so that they represent intervals’ borders, not times when data in db were recorded.

Method: Change structure of intervals to form a correct response.

Method: Fills WHERE clause of SQL request with date-related constraints.

Method: Fills LIMIT clause of SQL request based on user supplied parameters.

Method: Fills LIMIT parameters of SQL request based on user supplied parameters.