1. Relational Databases

2. Database Large collection of data in an organised format to allow access and control DBMS Database Management System - Special software that helps to maintain the database and control its use. DBA Database Administrator (or team) maintains the database(s)

3. Relational Database RDB Database based on the mathematical theory of relations (Ted Codd, IBM) Not to be confused with relationships which are logical connections between data.

4. A definition Logical – The way things appear to be (to the user) Physical – The way things really are (on the computer)

5. What makes RDB special? Data is tabular, we can view it in columns and rows There are no pointers or physical connections to represent relationships Uses an engine to match values “on the fly”. The order or columns and rows should not matter.

6. What are the benefits? You don’t get into a mess of broken pointers You can use tabular data to generate more tabular data You can more easily add or delete rows and you can split and merge data more easily You can store tables in different locations You can control row and column access You can sort data Data management can be separated into functions You only need one language to do everything

7. What is SQL SQL is Structured Query Language It is not perfect but it is the standard It varies a little between products It is composed of – SQLQuery – DCLControl – DDLDefinition – DMLManipulation

8. DBA Role Recovery (The most important priority). – Is the database in a consistent state at a point in time? Access – Are we protecting the data properly? – What are the users and roles and what access do they have? – What are the privacy requirements? Integrity – Can we trust the data? – How do we make structural changes?

9. Advanced Topics Concurrency – Multiple users accessing the same data at the same time – Locking – Versioning Transactions – All or nothing unit of work Distribution – Distributed data (Replication) – Distributed access Tuning – Optimising the database performance – What queries are taking the longest time? – What strategies can we use to improve performance ?