Access data elements by moving progressively downward from the root and along the branches of the tree
Any data element can be related to any number of other data elements
Three basic operations on relational databases
OLAP is used for answers to complex business queries, discussed in detail in chapter 9
Gap in performance between relational and hierarchical and network is rapidly narrowing
Database planning, beyond that of a personal or small business end user database created by a database management package, typically requires use of a top-down data planning process based upon the systems development model covered earlier: 1. Data Planning. At this stage, planners develop a model of business processes. This results in an enterprise model of business processes with documentation. 2. Requirements Specification. This stage defines the information needs of end users in a business process. Description of needs may be provided in natural language or using the tools of a particular design methodology. 3. Conceptual Design. This stage expresses all information requirements in the form of a high-level model. 4. Logical Design. This stage translates the conceptual model into the data model of a DBMS. 5. Physical Design. This stage determines the data storage structures and access methods.
Discussed in more detail in chapter 9
Traditional file processing leads to not being able to find data because it’s in multiple files. Or it’s too costly to combine and clean. Data redundancy – duplicated data in several files Data is not integrated across files. Data dependence – software had references to format of data. So maintenance was difficult. Inconsistency across files. Problems resolved with Database Management Approach
Database interrogation is major advantage of DBMS approach SQL is pronounced Sequel
Объект хандалтат бүтэц
Source: Adapted from Ivar Jacobsen, Maria Ericsson, and Ageneta Jacobsen, The Object Advantage: Business Process
Reengineering with Object Technology (New York: ACM Press, 1995), p. 65.
Copyright @ 1995, Association for Computing Machinery. By permission.