Agree with Stefano.
I don't recommend uploading data to BC (On-premise) using SQL. Process might be easy but it can cause validation errors and open up whole new set of issues for you. You have different options available:
1. If you want a direct upload, then you can use "Configuration Package".
2. You can create XML ports : This will allow you alter the data and also run validations before creating new documents.
3. You can use Flow with standard BC connector which has the entities you interested in. : You can schedule the process to monitor a folder, pick the CSV file and create documents.
