Systems analysis and development CIS210 ch 10

CIS 210 Systems Analysis and Development Week Part II Designing Databases Objectives • Upon completion of part II you will be able to: – Understand and be able to explain the concepts related to key database design terminology – Understand and be able to transform E-R diagrams into an equivalent set of well-structured and normalized relationships – Understand and be able to merge normalized relations from several user views into a consolidated set of well-structured relations – Understand and be able to explain the concepts related to storage formats in database tables – Understand and be able to translate well-structured relations into efficient database tables – Understand and be able to explain the concepts related to different methods of storing data in computer files Overview • Database Design Guidelines – Database files – Logical design – Physical design • Design Purposes – – – – – Table structure Logical design Physical design Translate relational database model Choose storage technologies Database Design • Logical Database Design – Four key steps • • • • Develop model Combine requirements Translate conceptual model Compare logical model with E-R model • Physical Database Design – – – – – Use results of logical design Attributes Descriptions of data Expectations Descriptions of technologies • Deliverables – Normalized relations – Specifications for computer files Relational Database Model • Overview – Data in the form of tables (relations) – Named columns – Unnamed rows • Properties of Relations – – – – – Simple entries in cells Column entries from the same set of values Unique rows Interchanged sequence of columns Interchanged sequence of rows • Well-Structured Relations – Minimum redundancy – Modification without inconsistency Normalization • Defining Normalization – Converting complete structures into simple stable data structures – Based on well-accepted principles and rules • Functional Dependence and Primary Keys • Second Normal Form (2NF) • Third Normal Form (3NF) – Foreign key – Referential integrity Transforming Diagrams Into Relations • Represent Entities – Each entity type becomes a relation – Identifier becomes primary key – Other attributes become nonprimary keys • Represent Relationship – Each relationship must be represented • Normalize the Relations • Merge the Relations Physical File and Database Design • Designing Fields – Choosing data types • • • • Minimize storage space Represent all possible values Improve data integrity Support data manipulations – Controlling data integrity • • • • Default value Range control Referential integrity Null value control Physical File and Database Design • Designing Physical Tables – Overview • Physical table • Denormalization – Arranging table rows • Sequential file organization • Indexed file organization • Hashed file organization – Designing controls for files • File restoration techniques Summary • • • • Logical Database Design Normalization Transforming Diagrams Physical File and Database Design ... Understand and be able to explain the concepts related to key database design terminology – Understand and be able to transform E-R diagrams into an equivalent set of well-structured and normalized... normalized relationships – Understand and be able to merge normalized relations from several user views into a consolidated set of well-structured relations – Understand and be able to explain the concepts... to storage formats in database tables – Understand and be able to translate well-structured relations into efficient database tables – Understand and be able to explain the concepts related to