There are different ways to build this cron/scheduled job to pull and store data into oracle DB. Since you wanted this to be built in oracle, below instructions are one way to achieve this.
1. Pull Data from Quickbase using HTTP API that gives data in XML format.
Refer to the NOTES below for Quickbase API information.
2. Build an oracle stored procedure using PL/SQL, use HTTPURITYPE to consume HTTP GET request and read XML data received using Quickbase HTTP API. Use below link on how to do this.
3. Once the stored procedure is ready, schedule it for timely download. Use below link for setting up scheduler.
4. Use XMLTABLE to extract the data received from Quickbase API GET Response. Follow below link for using this or any other oracle library to read XML response.
Quickbase exposes HTTP API to read data, follow the below guide hosted by Quickbase to read data out of it in XML.
Steps to read Data
Use API_Authenticate to get ticket which can be used to make
Let me know if you need any additional information.