Databases Creating databases to store information

Learning Objectives 1. Explain what a database is, including common database terminology, and list some of the advantages and disadvantages of using databases. 2. Discuss some basic concepts and characteristics of data, such as data hierarchy, entity relationships, and data definition. 3. Describe the importance of data integrity, security, and privacy, and how they affect database design. Understanding Computers: Today and Tomorrow, 14th Edition 2 2

Learning Objectives 4. Identify some basic database classifications and discuss their differences. 5. List the most common database models and discuss how they are used today. 6. Understand how a relational database is designed, created, used, and maintained. 7. Describe some ways databases are used on the Web. Understanding Computers: Today and Tomorrow, 14th Edition 3

Breaking into database development 1.A nalysis Who will use it and how? 2.D esign What data should it have? Should it have forms? 3.D evelop Creation 4.I mplement Get rid of the “bugs” 5.M aintain Keeping it running From SDLC, break into DDLC

5 2 What Is a Database?  A collection of related data stored in a manner so it can be retrieved as needed  Database management system (DBMS):  A system used to create, maintain, and access databases  DBMSs include:  Personal  Microsoft Access,  Corel Paradox  Lotus Approach  Enterprise databases  Oracle Database  IBM DB2  Microsoft SQL Server

Who uses databases? Department of Motor Vehicles Amazon – largest database on the Web El Camino College Search sites – Internet keyword search – Google, Bing, Yahoo! Search, Microsoft Live Search, Ask.com 60% of web page connections linked from search sites

Database Careers  Individuals involved with a DBMS:  Database designers:  Designs and creates the database and its objects  Database administrators:  Responsible for managing the databases within an organization  Makes sure they have disk space  Makes sure they are secure  Users:  Individuals who enter data, update data, and retrieve information out of the database

How does a database work?

9 Databases and the Web Databases are commonly used on the Web Information retrieval, e-commerce, dynamic Web pages (change based on user input), etc.

10 Database Hierarchy Database: Contains a group of related tables Tables: Contains collection of related records Records(rows): Contains collection of related fields in a database (all the fields for one customer, for example) Fields(columns): Single category of data to be stored in a database (name, telephone number, etc.) Data(characters): letters, numbers, symbols

11 Data Concepts and Characteristics  Relationships: Describe an association between two or more tables  One-to-one (1:1) entity relationships (not common)  e.g. each school has one president and a president is only at one school  One-to-many (1:M) entity relationships (most common)  e.g. a employee earns one or more paychecks and each paycheck is for only one employee  Many-to-many (M:N) entity relationships (requires a third table to tie the tables together)  e.g. a teacher teaches one or more students and a student has one or more teachers

Tables Relational databases arrange fields into structures called tables  Each table contains a collection of fields (columns) – each field is a particular piece of information  A set of related fields (collection of related information) is called a record (row)

Relationships through Common fields Each table may relate to one or more other tables in the database through common fields with common values.

Primary Keys  Each record in a table should have a field/fields which make that record unique and identifiable from the other records Must have unique data (not duplicated) Must have data that doesn’t change Special meaning in a relational database – it is used to connect 2 tables

Foreign Keys – how tables talk to each other  The common field in the related table is called a foreign key - it links to the primary key column(s) in another table, thereby creating a relationship.

Constraints  Manage the REFERENTIAL INTEGRITY of the data  Cascade Updates and Cascade Deletes  Eliminates orphan records

Fine-tuning the database design  Data definition: The process of describing the properties of data to be included in a database table  During data definition, each field is assigned:  Name (must be unique within the table)  Data type (such as Text, Number, Currency, Date/Time)  Description (optional description of the field)  Properties (field size, format of the field, allowable range, if field is required, etc.)  Finished specifications for a table become the table structure

Keeping it Meaningful  Data integrity: The accuracy of data  Quality of data input determines the quality of retrieved information (GIGO)  Data validation: Ensuring that data entered into the database is valid  Record validation rules: Checks all fields before changes to a record are saved  Can be enforced on a per transaction basis so the entire transaction will fail if one part is invalid

Installing the Information System  After all programs and database are created, they are tested to make sure they work well together  “Information System” is then ready to be used

Wrapping it up Large companies(like Amazon, Home Depot, Kaiser, etc.) have an Integrated Enterprise type of Information System – Activities are designed to work together throughout the enterprise – Enterprise Resource Planning (ERP) system Large integrated system that ties together all of a business’s activities Most common ERP systems are Inventory related – track and control inventory Supply Chain Management (SCM) – reduce operating costs while meeting delivery objectives deliver the right product, to the right place, at the right time, at the right price Product Lifecycle Management (PLM) – manages a product as it moves through its life cycle, from design, to development, to retirement

Wrapping it up Information systems have a life cycle (FADDIM) Systems Analyst studies business problem uses tools such as ERD’s (entity-relationship diagrams), DFD’s (data flow diagrams) and DT’s (decision tree’s) to collect and analyze data Programmer develops software Uses tools such as SDK’s (software development kits), API’s (application programming interfaces), flowcharts to help create the programs

Wrapping it up It takes programs and data to make the information system work Objective: Business Intelligence through data mining,