Customer details are stored within the customers table, while the sales order details are stored within the transaction table. To gather associated Customer details for a specific Sales Order, both tables should be joined together. In the situation of a Sales Order, the entity_id of transaction is the customer_id in the customer table. Therefore, the entity_id and customer_id columns can be used to link both tables.
Please refer to sample query below:
SELECT so.transaction_number, so.trandate, c.full_name FROM Transactions so INNER JOIN Customers c ON so.entity_id = c.customer_id WHERE so.transaction_type = 'Sales Order'