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1、Data MODELING AND AnalysisWhat Is Data Modeling?Data modeling is a technique for organizing and documenting a systems data.Data modeling is sometimes called database modeling because a data model is usually implemented as a database.System Concepts For Data Modeling Entities a class of persons,place
2、s,objects,events,or concepts about which we need to capture and store data.Attributes a descriptive property or characteristic of an entity.Synonyms include element,property,and field.Relationships a natural business association between one one or more entities.Relationships nonidentifying relations
3、hi a relationship in which each participating entity has its owm independent primary key.identifying relationship a relationship in which the parent entitys key is also part of the primary key of the child entity.nonspecific relationship a relationship where many instances of an entity are associate
4、d with many instances of another entity.Also called many-to-many relationship.The Process Of Logical Data ModelingStrategic Data ModelingData Modeling during Systems AnalysisLooking Ahead to Systems DesignAutomated Tools for Data ModelingHow to Construct Data ModelsEntity DiscoveryThe Context Data M
5、odelThe Key-Based Data ModelGeneralized HierarchiesThe Fully Attributed Data ModelAnalyzing the Data Model What is a Good Data Model?1.A good data model is simple.2.A good data model is essentially nonredundant.3.A good data model should be flexible and adaptable to future needs.Data Analysis a tech
6、nique used to improve a data model for implementation as a database.Normalization Example a data analysis technique that organizes data into groups to form nonredundant,stable,flexible,and adaptive entities.Normalization first normal form(1NF)an entity whose attributes have no more than one value fo
7、r a single instance of that entity.second normal form(2NF)an entity whose non-primary-key attributes are dependent on the full primary key.third normal form(3NF)an entity whose non-primary-key attributes are not dependent on any other non-primary-key attributes.Mapping Data Requirements to Locationsdata-to-location-CRUD matrix a matrix that is used to map data requirements to locations.