Database Systems 1. The purpose of the lecture Learn to use database management software to develop data-intensive applications Become familiar with fundamental. - презентация

1 Database Systems 1

2 The purpose of the lecture Learn to use database management software to develop data-intensive applications Become familiar with fundamental DBMS (СУБД) concepts Gain exposure to future trends in databases 2

3 Typical roles and career path for database professionals Data Architect Database Architect Database Administrator (DBA) Application Developer 3

4 Illustrative Capabilities: A. Real Estate Information System: Successful students will be able to design and create a Web-accessible database for a real estate company to keep track of their rentals, lease renewals, and such. Included in this is the ability to write applications for the users of the database such as maintenance personnel, the property manager, and others. 4

5 Text book: Thomas M. Connolly, et al. Database Systems: A practical approach to Design, Implementation, and Management. 3rd Edition ISBN: Addison-Wesley, 2001 Grading policy 5

6 Agenda Unit 1. Database Systems 1.1 Introduction to Databases and Systems What is a Database? Examples of Database Systems When is a Database Management System Needed? When is a Database Management System Not Needed? (PrimaryKey, Alternate Key, Foreign Key) 6

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20 Example Library DBMS 20

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26 Information model An information model is an abstract, formal representation of entities that includes their properties, relationships and the operations that can be performed on them. 26

27 Data Model The primary motivation behind the concept is to formalize the description of a problem domain without constraining how that description will be mapped to an actual implementation in software. There may be many mappings of the Information Model. Such mappings are called data models 27

28 Relationship between an Information Model and a Data Model 28

29 Types of information models Network (CODASYL): 1970s Hierarchical (IMS): late 1960s and 1970s Relational: 1970s and early 1980s Entity-Relationship: 1970s Extended Relational: 1980s Semantic: late 1970s and 1980s Object-oriented: late 1980s and early 1990s Object-relational: late 1980s and early 1990s Semi-structured (XML): late 1990s to the present 29

30 Entity-Relationship model The relational data model is simple and elegant. It has a solid mathematic foundation based on sets theory and predicate calculus and is the most used data model for databases today. Peter Chen (1976) proposed thinking of a database as a collection of instances of entities. Entities are objects that have an existence independent of any other entities in the database. Entities have attributes, which are the data elements that characterize the entity. One or more of these attributes could be designated to be a key. Lastly, there could be relationships between entities. Relationships could be 1-to-1, 1-to-n, n-to-1 or m-to-n, depending on how the entities participated in the relationship. Relationships could also have attributes that described the relationship. 30

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