True ETL Tools
If you need more than just to copy data from Xero to MariaDB, you may use Skyvia's powerful ETL functionality for Xero and MariaDB integration. Skyvia's Import tool will correctly extract Xero data, transform it, and load to MariaDB when MariaDB tables have different structure than Xero objects. Moreover, Skyvia Import allows loading data in any direction, supporting Reverse ETL scenario.
For more complex cases, you can use Data Flow and Control Flow tools. They are designer-based solutions for creating complex data pipelines, involving not only Xero and MariaDB connectors, but any number of connectors in one integration. With these tools you can automate data workflows, involving custom logic, complex multistage transformations, combine data from different sources, load them into multiple destinations at once and many more.