1. History of Implementation Data Models

2. Databases were: Early Business Computer Systems –Accounting functions - payroll, profit/loss statements Files of data - file oriented (physical hardware) – sequential and random access (index)

3. In 1960's needed: Integrated centralized data structure Redundancy DBA's Data models

4. Mid 1960's - Hierarchical data model logical level - data relationships relationships structured as hierarchies parents and children child can have only 1 parent 1-to-many

5. Hierarchical Example department customer Employee project invoice store dep super worker invoice_line contact

6. Hierarchical DB Used pointers Any query through the data followed pointers manipulated 1 row at a time how about many-to-many relationships? Problems?

7. Late 1960's - Network Model many-to-many relationships more than 1 parent Owner-Member Relationship Instances or Occurrences Problems?

8. Network example Sales rep customer invoice store invoice _line contact

9. 1970's Relational Model - E.F. Codd Rows and Columns Instead of 1 record at a time, files or sets at a time Easier to write queries Limitations?

10. Relational example Customer: CID storeID contact Invoice# Sales Rep: SRID Invoice # InvoiceLine

11. 1980's Object-Oriented DBs Represent real-world entities as objects –Objects and relationships –Classes and instances – Specialization /Generalization – Inheritance, methods Similar to hierarchical Most versions based on relational Problems?

12. 1990’s – Extend Relational Object-Relational DBs –Keep relational, but add OO features Additional Issues: –Distributed DBs –Data mining and data warehouses –Real-time Databases

13. 2000’s – Recent Issues Data integration Database Security Web Databases & Information Retrieval XML Databases Mobile Databases Sensor Databases Data-intensive computing (Data Grids) Cloud computing - where do databases fit in?