Database Management System Chapter 1

Database Management System Chapter 1 Database ️A collection of organized data that allows access, retrieval, and use of data. Database Management System (DBMS) ️Software through which users and application programs interact with a database Character ️Any written or printed letter, number, or symbol Field ️Group of related characters. Ex. Customer Name. Corresponds to Column in physical database Record ️a collection of fields about 1 customer (name, address, city, state, etc.) Corresponds to row in a physical database. File ️A group of records about the same type of entity (customers or inventory items) DBMS Functionality ️*Data Storage: Manage the physical structure of the database. *Security: control user access and privileges. *Multiuser access: Manage concurrent data access. *Backup: enable recovery options for database failures. *Data access language: provide a language that allows database access. *Data integrity: Enable constraints or checks on data. *Data dictionary: maintain information about database structure. Systems Development Life Cycle (SDLC) ️1. Systems investigation: Understanding the problem 2. Systems analysis: Understanding the solution to the previously identified problem 3. Systems design: Defining the logical and physical components. 4. Systems implementation: Creating the system 5. Systems integration and testing: Placing the system into production. 6. Systems deployment: Placing the system into production. 7. Systems maintenance and review: Evaluating the implemented system. Entity ️Any person, place, or thing with characteristics or attributes that will be included in the system. Entity-Relationship Model (E-R Model) ️Used to depict the relationship that exists among entities E-R Model Relationships ️One-to-one One-to-many Many-to-many One-to-one Relationship ️Each occurrence of data in one entity is represented by only one occurrence of data in the other entity. Ex. Each individual has just one SSN and each SSN is assigned to just one person. One-to-many Relationship ️Each occurrence of data in one entity can be represented by many occurrences of the data in the other entity. Ex. A class has only one instructor, but each instructor can teach many classes. Many-to-many Relationship ️Data can have multiple occurrences in both entities. Ex. A student can take many classes, and each class is composed of many students. Cannot be included in the physical database. Database Normalization ️Determines required tables and columns for each table. Multistep process. Used to reduce or control data redundancy. Data redundancy ️When the same data exists in more than one place in a database. Data anomalies ️refers to data inconsistencies Unnormalized Data ️contains repeating groups in the Author column in the BOOKS table First-Normal Form (1NF) ️A relation that has a primary key and in which the