ISYS 250 Lecture Notes - Lecture 3: Data Model, Foreign Key, Unique Key

• School: Maryville University of St. Louis
• Department: Information Systems
• Course: ISYS 250
• Professor: Robert Frese

Document Summary

Infernal data an organization the organization internal collected from wmon stored on database. Pointer to the disk location of the record matching the index value. Logical database design: information viewed in database in two days. Physical involves how data is stored on and retrieved from storage media. Logical involves how information appears to users and how it can be organized and retrieved. Data model determine how data created, represented, organized and maintained. Two-dimension table of rows and columns of data. Stores de nitions, such as data types for elds, defaults value, and validation rules for data in each. Uniquely identi es every record in a relational data base. Field in a relational table that mathches the primary key column of another table. Encapsulation- grouping objects along with their attributes and methods into a class. Inheritance- new objects can be created faster and more easily by entering new data in attributes. Raw data - information in its original form.