From Codd's 12 rules (emphasis mine): > For any system that is advertised as, or claimed to be, a relational > data base management system, that system must be able to manage data > bases entirely through its ***relational capabilities***. What does *"relational capabilities"* mean here? Does it mean that you could manage the database by only using a language like SQL? Does it mean anything beyond this?

Fundamental question that I cannot seem to find an answer on. I have a database that stores line items from receipts along with the username and receipt number. Right now the lineItem column is just a long string of data separated by commas (original file appears to have been just an Excel file). This information is parsed in a PHP script for viewing on the front end. The table looks like this: |----------|----------|----------| |lineItem |receiptID |customerID| |----------|----------|----------| |CD, DVD, |001 |User01 | |----------|----------|----------| |CD, CD, |002 |User02 | |DVD, usb, | | | |----------|----------|----------| Ultimately, **is this bad practice**? Should the lineItem values be linked to related values in another table instead maybe?

Among Codd's 12 rules for Relational Database Management Systems is Rule 1, which states the following: > **Rule 1**: Information rule > > All information(including metadata) is to be > represented as stored data in cells of tables. The rows and columns > have to be strictly unordered. Why is it important that metadata be stored in tables?