IT 2105 Mathematics for Computing I Bachelor of

IT 2105 Mathematics for Computing I Bachelor of Information Technology Database Systems I IT 2305 07. Database Design Process 7. 1 Database Design Approach 7. 1. 1. Introduction U J Prashad Srilal BSc (Hons) in Business IT

IT 2305_Database Systems I Intended Learning Outcomes After completing this module students should be able to; • Describe the Database Design Approach

IT 2305_Database Systems I Outline • Introduction, • Benefits, • Critical success factors, • Where it fits into the application development process, • Approach

IT 2305_Database Systems I Database Design • Database design and the creation of an entity relationship diagram (also known as an "ERD" or data model) is an important yet sometimes overlooked part of the application development lifecycle. • An accurate and up-to-date data model can serve as an important reference tool for DBAs, developers, and other members of a JAD (joint application development) team. • The process of creating a data model helps the team uncover additional questions to ask of end users.

IT 2305_Database Systems I Database Design • Effective database design also allows the team to develop applications that perform well from the beginning. • By building quality into the project, the team reduces the overall time it takes to complete the project, which in turn reduces project development costs. • The central theme behind database design is to "measure twice, cut once".

IT 2305_Database Systems I Database Design • Data modeling is essential to building a well-functioning database. • For a database to support the activities of a business, it needs a good blueprint and foundation: the data model. • A data model represents a business' data.

IT 2305_Database Systems I Critical Success Factors in Database Design • Work interactively with the users as much as possible. • Follow a structured methodology throughout the data modelling process. • Employ a data-driven approach. • Incorporate structural and integrity considerations into the data models. • Combine conceptualization, normalization, and transaction validation techniques into the data modelling methodology.

IT 2305_Database Systems I Critical Success Factors in Database Design • Use diagrams to represent as much of the data models as possible. • Use a Database Design Language (DBDL) to represent additional data semantics. • Build a data dictionary to supplement the data model diagrams. • Be willing to repeat steps.

IT 2305_Database Systems I Information System Provides for data collection, storage, and retrieval Composed of: People, hardware, software Database(s), application programs, procedures Systems analysis Process that establishes need for and extent of information system Systems development Process of creating information system

IT 2305_Database Systems I Information System Applications Transform data into information that forms basis for decision making Usually produce the following: Formal report Tabulations Graphic displays Composed of following two parts: Data Code by which data are transformed into information

IT 2305_Database Systems I SDLC

IT 2305_Database Systems I Question Which of the following is correct about database design? (a) Employ a data-driven approach. (b) Build a data dictionary to supplement the data model diagrams. (c) Be willing to repeat steps. (d) Incorporate structural and integrity considerations into the data models. (e) All of the above

IT 2305_Database Systems I Answer Which of the following is correct about database design? (a) Employ a data-driven approach. (b) Build a data dictionary to supplement the data model diagrams. (c) Be willing to repeat steps. (d) Incorporate structural and integrity considerations into the data models. (e) All of the above

IT 2305_Database Systems I Design Methodology A structured approach that uses procedures, techniques, tools, and documentation aids to support and facilitate the process of design.

IT 2305_Database Systems I Design Methodology The database design process can be broken down into four phases. 1. Requirement collection and analysis phase 2. Conceptual design 3. Logical design 4. Physical design

IT 2305_Database Systems I Overview DB Design Methodology Conceptual database design Step 1 Build conceptual data model Step 1. 1 Identify entity types Step 1. 2 Identify relationship types Step 1. 3 Identify and associate attributes with entity or relationship types Step 1. 4 Determine attribute domains Step 1. 5 Determine candidate, primary, and alternate key attributes

IT 2305_Database Systems I Overview DB Design Methodology Step 1 Build conceptual data model (continue) Step 1. 6 Consider use of enhanced modeling concepts (optional step) Step 1. 7 Check model for redundancy Step 1. 8 Validate conceptual model against user transactions Step 1. 9 Review conceptual data model with user

IT 2305_Database Systems I Overview DB Design Methodology Logical database design for the relational model Step 2 Build and validate logical data model Step 2. 1 Derive relations for logical data model Step 2. 2 Validate relations using normalization Step 2. 3 Validate relations against user transactions Step 2. 4 Define integrity constraints

IT 2305_Database Systems I Overview DB Design Methodology Physical database design for relational database Step 3 Translate logical data model for target DBMS Step 3. 1 Design base relations Step 3. 2 Design representation of derived data Step 3. 3 Design general constraints

IT 2305_Database Systems I Overview DB Design Methodology Step 4 Design file organizations and indexes Step 4. 1 Step 4. 2 Step 4. 3 Step 4. 4 Analyze transactions Choose file organization Choose indexes Estimate disk space requirements

IT 2305_Database Systems I Overview DB Design Methodology Step 5 Design user views Step 6 Design security mechanisms Step 7 Consider the introduction of controlled redundancy Step 8 Monitor and tune the operational system

IT 2305_Database Systems I Poor DB design • A poor database design can cripple an application, producing problems with redundancy, inaccuracy, consistency, and concurrency of your data. • Normalization is a process that serves to reduce, if not eliminate, these problems with data.

IT 2305_Database Systems I Logical Data Model • A set of data structures assembled following rules that describe the processing requirements (access paths) of the data in terms of a logical database model • Done by a Data Analyst • Not constrained by technology (? )

IT 2305_Database Systems I Physical Data Model • A model prepared for the purpose of implementing a database that runs under the control of a particular DBMS (product) • Done by a DBA • Constrained by Technology

IT 2305_Database Systems I Database Development Activities • Enterprise Modeling • Conceptual Data Modeling • Logical Database Design • Physical Database Design and Creation • Database Implementation • Database Maintenance

IT 2305_Database Systems I Question Which of the following is not in DB design ? (a) Requirement collection and analysis phase (b) SQL design (c) Conceptual design (d) Logical design (e) Physical design

IT 2305_Database Systems I Answer Which of the following is not in DB design ? (a) Requirement collection and analysis phase (b) SQL design (c) Conceptual design (d) Logical design (e) Physical design

IT 2305_Database Systems I Lesson Summary • Introduction, • Benefits, • Critical success factors, • Where it fits into the application development process, Approach

IT 2105 Mathematics for Computing I Bachelor of Information Technology Database Systems I IT 2305 07. Database Design Process 7. 1 Database Design Approach 7. 1. 1. Introduction U J Prashad Srilal BSc (Hons) in Business IT