I'm using Skyvia to load data from QuickBooks Online (QBO) into a SQL database. However, I want to avoid reloading all the data each time. Instead, I want to incrementally update my SQL database by only bringing in new records and updating existing ones, while preserving custom fields in the SQL database.

Here are my specific requirements:

1. Extract only new and updated records from QBO using Skyvia.
2. Load these records into staging tables.
3. Merge the staging data into the main tables, inserting new records and updating existing ones without affecting custom fields.

Could anyone provide a detailed process or examples on how to set this up, including SQL scripts for merging data?

Thank you for your help!