DevOps, CI/CD and Automation

hi all!
being a new programmer in XML world,my question might sound a bit stupid but your answers would mean a world to me. i have to generate a single XML document from my database by querying more than one table. for example i have 3 tables i.e HR_EMP_NAME, HR_PRODUCTS_DETAIL, HR_PAYROLL_SUMMARY. all three tables have completely different columns except one ID column which is a foreign kay from HR_MASTER_LIST. i want to get any insert operation on these tables as a single document. so far as i have studied, one option is to generate XMLDoc using XSU and then add child nodes using JAXP but i am ot geting the logic right.
please do reply.

thanks a lot
usman