An important feature of relational database management systems is that a single database can be spread across several tables.  For example for customer information would be saved in another Table may be named as Customer_table and for recording purchasing there would be another table can be named purchase_transaction. So with every new purchase by the same customer it will linked with customer table with associated customer_code  So when customer change an address it will be updated in all rows depending on how we are managing records. Sometime we need customer history and we have to manage how customer table would be updated.

Basically both flat file and RDBMS have their own place in database management. A data from RDBMS like MS Access can be exported to Spreadsheet or word files, and can be imported back to MS Access as well.