Database development life cycle
- 1. DATABASE DEVELOPMENT LIFE CYCLE AFRASIYAB HAIDER DATABASE DEVELOPMENT LIFE CYCLE Database development life cycle A database is usually a fundamental component of the information system, especially in business oriented systems. Thus database design is part of system development. The following picture shows how database design is involved in the system development lifecycle. The phases in the middle of the picture (Database Design, Database Implementation) are the phases that you concentrate on in the Database Design course. The other phases are briefly described. They are part of the contents of the Systems Analysis and Design courses, for example. There are various methods of how the different phases of information systemdesign, analysis and implementation can be done. Here the main tasks or goals are described but no method is introduced.
- 2. DATABASE DEVELOPMENT LIFE CYCLE AFRASIYAB HAIDER DATABASE DEVELOPMENT LIFE CYCLE Database Planning The database planning includes the activities that allow the stages of the database system development lifecycle to be realized as efficiently and effectively as possible. This phase must be integrated with the overall Information System strategy of the organization. The very first step in database planning is to define the mission statement and objectives for the database system. That is the definition of: - the major aims of the database system - the purpose of the database system - the supported tasks of the database system - the resources of the database system Systems Definition In the systems definition phase, the scope and boundaries of the database application are described. This description includes: - links with the other information systems of the organization - what the planned systemis going to do now and in the future - who the users are now and in the future. The major user views are also described. i.e. what is required of a database systemfrom the perspectives of particular job roles or enterprise application areas. Requirements Collection and Analysis During the requirements collection and analysis phase, the collection and analysis of the information about the part of the enterprise to be served by the database are completed. The results may include eg: - the description of the data used or generated - the details how the data is to be used or generated - any additional requirements for the new database system Database Design The database design phase is divided into three steps: - conceptual database design - logical database design - physical database design
- 3. DATABASE DEVELOPMENT LIFE CYCLE AFRASIYAB HAIDER DATABASE DEVELOPMENT LIFE CYCLE In the conceptual database design phase, the model of the data to be used independent of all physical considerations is to be constructed. The model is based on the requirements specification of the system. In the logical database design phase, the model of the data to be used is based on a specific data model, but independent of a particular database management system is constructed. This is based on the target data model for the database e.g. relational data model. In the physical database design phase, the description of the implementation of the database on secondary storage is created. The base relations, indexes, integrity constraints, security, etc. are defined using the SQL language. Database Management System Selection This in an optional phase. When there is a need for a new database management system (DBMS), this phase is done. DBMS means a database system like Access, SQL Server, MySQL, Oracle. In this phase the criteria for the new DBMS are defined. Then several products are evaluated according to the criteria. Finally the recommendation for the selection is decided. ApplicationDesign In the application design phase, the design of the user interface and the application programs that use and process the database are defined and designed. Protyping The purpose of a prototype is to allow the users to use the prototype to identify the features of the system using the computer. There are horizontal and vertical prototypes. A horizontal prototype has many features (e.g. user interfaces) but they are not working. A vertical prototype has very few features but they are working. See the following picture. Implementation During the implementation phase, the physical realization of the database and application designs are to be done. This is the programming phase of the systems development. Data Conversion and Loading This phase is needed when a new database is replacing an old system. During this phase the existing data will be transferred into the new database.
- 4. DATABASE DEVELOPMENT LIFE CYCLE AFRASIYAB HAIDER DATABASE DEVELOPMENT LIFE CYCLE Testing Before the new systemis going to live, it should be thoroughly tested. The goal of testing is to find errors! The goal is not to prove the software is working well. Operational Maintenance The operational maintenance is the process of monitoring and maintaining the database system. Monitoring means that the performance of the systemis observed. If the performance of the system falls below an acceptable level, tuning or reorganization of the database may be required. Maintaining and upgrading the database systemmeans that, when new requirements arise, the new development lifecycle will be done. Source: Connolly, Begg. 2005. Database Systems. A Practical Approach to Design, Implementation, and Management. Addison Wesley. Chapter 9. Database Planning, Design and Administration.