DATA MODELS.pptx

DATA MODEL 8-1 Information system Information system consists of a database (containing stored data) together with programs that capture, store, manipulate, and retrieve the data. Database is specified by a data model, describing what sort of data will be held and how it will be organized. 8-2 ...

DATA MODEL 8-1 Information system Information system consists of a database (containing stored data) together with programs that capture, store, manipulate, and retrieve the data. Database is specified by a data model, describing what sort of data will be held and how it will be organized. 8-2 DATA MODELING AND ANALYSIS McGraw-Hill/Irwin Copyright © 2007 by The McGraw-Hill Companies, Inc. All rights reserved. DATA MODELING AND ANALYSIS McGraw-Hill/Irwin Copyright © 2007 by The McGraw-Hill Companies, Inc. All rights reserved. DATA MODELING AND ANALYSIS McGraw-Hill/Irwin Copyright © 2007 by The McGraw-Hill Companies, Inc. All rights reserved. DATA MODEL 8-6 McGraw-Hill/Irwin Copyright © 2007 by The McGraw-Hill Companies, Inc. All rights reserved. Data Model Data model is a conceptual representation of the data structures that are required by a database. A data model can be though of as a diagram or flowchart that illustrates the relationship between data. A data model is independent of hardware or software constraints. 8-8 Data Model: Entity 8-9 Data Model: Entity Entity – a class of persons, places, objects, events, or concepts about which we need to capture and store data. Synonym – table. Entity instance – a single occurrence of an entity. Synonyms – record, row. Attribute – a descriptive property or characteristic of an entity. Synonyms - property, field, column. Key – an attribute, or a group of attributes, that assumes a unique value for each entity instance. Ex. Primary key 8-10 Entity Relationship Diagram (ERD) relationship The ERD is a schematic representation of the database. A Data Element Dictionary (DED) is a text representation. The two must be combined to get a clear picture of the data model. 8-11 Data Model: Relationships Relationship – a natural business association that exists between one or more entities. The relationship may represent an event that links the entities or merely a logical affinity that exists between the entities. 8-12 Data Model Types 8-13 Data Model Types 1. Conceptual Data Model is a visual representation of database concepts and the relationships between them identifying the high-level user view of data. Rather than the details of the database itself, it focuses on establishing entities, characteristics of an entity, and relationships between them. 2. Logical data model is used for a specific project since the purpose is to develop a technical map of rules and data structures. 3. Physical data model is a schema or framework defining how data is physically stored in a database. 8-14 Data Modeling Approaches: 1.Semantic Modeling 2.Relational Modeling 3.Entity Relationship Modeling 4.Binary Modeling 8-15 DATA MODELING Lesson Objectives  Define simple data model.  Understanding of significance of data model.  Examples of data model. Data requirements are recorded as a conceptual data model with associated data definitions. Actual implementation of the conceptual model is called a logical data model. To implement one conceptual data model may require multiple logical data model. Data Modeling Types • Strategic data modeling • Data modeling during system analyst Importance of Data Modeling The goal of the data model is to make sure that the all data objects required by the database are completely and accurately represented. The Entity-Relation Model (ER) is the most common method used to build data models for relational databases. Simple Data Model A flat file is a type of database that stores data in a single table. Standard Data Model or industry standard data model (ISDM) is a data model that is widely applied in some industry, and shared amongst competitors to some degree. NORMALIZATION 1NF, 2NF, 3NF Lesson Objectives  Normal Form  Examples of tables in first normal form  Second Form  Third Form Insert McGraw-Hill/Irwin Copyright © 2007 by The McGraw-Hill Companies, Inc. All rights reserved. Normalization Normalization is a process for assigning attributes to entities. It reduces data redundancies and helps eliminate the data anomalies (insertion anomaly, update anomaly, deletion anomaly). Normal Form The Normal Form (NF) of relational database theory provide criteria for determining a table’s degree of vulnerable it is to inconsistencies and anomalies. Insert McGraw-Hill/Irwin Copyright © 2007 by The McGraw-Hill Companies, Inc. All rights reserved. Insert McGraw-Hill/Irwin Copyright © 2007 by The McGraw-Hill Companies, Inc. All rights reserved. Insert McGraw-Hill/Irwin Copyright © 2007 by The McGraw-Hill Companies, Inc. All rights reserved. Insert McGraw-Hill/Irwin Copyright © 2007 by The McGraw-Hill Companies, Inc. All rights reserved. McGraw-Hill/Irwin Copyright © 2007 by The McGraw-Hill Companies, Inc. All rights reserved. McGraw-Hill/Irwin Copyright © 2007 by The McGraw-Hill Companies, Inc. All rights reserved. McGraw-Hill/Irwin Copyright © 2007 by The McGraw-Hill Companies, Inc. All rights reserved. McGraw-Hill/Irwin Copyright © 2007 by The McGraw-Hill Companies, Inc. All rights reserved. McGraw-Hill/Irwin Copyright © 2007 by The McGraw-Hill Companies, Inc. All rights reserved. McGraw-Hill/Irwin Copyright © 2007 by The McGraw-Hill Companies, Inc. All rights reserved.