Databases C HAPTER 10

10 Chapter 10: Databases2 Databases and Structured Fields  A database is a collection of information –Typically stored as computer files  A structured file uses a uniform format to store data in the file

10 Chapter 10: Databases3 Fields  Contain the smallest unit of meaningful information  Each field has a unique field name  Variable-length field vs. fixed-length field

10 Chapter 10: Databases4 Records  Collections of data fields Records can be displayed as rows in a table or as forms.

10 Chapter 10: Databases5 Records  Each kind of record is referred to as a record type

10 Chapter 10: Databases6 Records  A record that contains data is referred to as a record occurrence

10 Chapter 10: Databases7 Relationships and Cardinality  A flat file is a structured file that contains only one record type  A relationship is an association between data that is stored in different record types

10 Chapter 10: Databases8 Relationships and Cardinality  Cardinality refers to the number of associations that can exist between two record types

10 Chapter 10: Databases9 Hierarchical, Network, Relational, and Object-Oriented Databases  A hierarchical databases arranges record types in a hierarchy

10 Chapter 10: Databases10 Hierarchical, Network, Relational, and Object-Oriented Databases  The network database model allows many-to- many relationships in addition to one-to-many relationship

10 Chapter 10: Databases11 Hierarchical, Network, Relational, and Object-Oriented Databases  A relational database stores data in a collection of related tables

10 Chapter 10: Databases12 Hierarchical, Network, Relational, and Object-Oriented Databases  An object-oriented database stores data as objects, which can be grouped into classes and defined by attributes and methods

10 Chapter 10: Databases13 Data Management Software Microsoft Word allows you to create a table of information, such as a mailing list, which you can edit, sort, search, and print. In addition, you can merge data from the table with a template letter to create form letters, mailing labels, and envelopes. CLICK TO START

10 Chapter 10: Databases14 Data Management Software

10 Chapter 10: Databases15 Data Management Software  It is possible to enter data as an ASCII text file  Custom data management software  Data dependence vs. data independence

10 Chapter 10: Databases16 Database Management Systems

10 Chapter 10: Databases17 Database Management Systems  Database client software allows any remote computer or network workstation to access data in a database

10 Chapter 10: Databases18 Database Management Systems  Multiple users can interact with the same database

10 Chapter 10: Databases19 Databases and the Web  The Web provides opportunities and challenges for accessing databases –Static Web publishing –Dynamic Web publishing Server-side program

10 Chapter 10: Databases20 Databases and the Web

10 Chapter 10: Databases21 Databases and the Web  Forms can collect data, as well as specifications for a query –XForms

10 Chapter 10: Databases22 Databases and the Web  Several tools are available to help create server-side programs

10 Chapter 10: Databases23 XML Documents  Markup language allowing field tags, data, and tables to be incorporated into a Web document

10 Chapter 10: Databases24 XML Documents  Used to specify a standard structure of fields and records  Data in an XML document is searchable  XML is portable, but not optimized for many common database operations –Consider storing data in a relational database, managing it with RDBMS software, and generating XML documents for exchanging data over the Web

10 Chapter 10: Databases25 Defining Fields  The term database structure refers to the arrangement of fields, tables, and relationships in a database  Store last names and first names in separate fields  Use a primary key field to make each record unique  Use appropriate data types for each field

10 Chapter 10: Databases26 Defining Fields

10 Chapter 10: Databases27 Defining Fields  A computed field is a calculation that a DBMS performs during processing and stores temporarily  Uppercase and lowercase are not always treated the same –Case sensitive database  Use field formats to show what the data is supposed to look like when it’s entered  Use field validation rules to filter data

10 Chapter 10: Databases28 Normalization  Process that helps save storage space and increase processing efficiency –Reduces data redundancy

10 Chapter 10: Databases29 Organizing Records  Records can be organized in different ways, depending on use  Sorting –A table’s sort order refers to the order in which records are stored on disk –Sort key  Indexing –Similar to the index in a book

10 Chapter 10: Databases30 Organizing Records When indexed by date, the index file contains a list of keys and the record number (R#) that contains more information about the album released on that date.

10 Chapter 10: Databases31 Designing the Interface  Arrange fields in a logical order  Provide visual clues to the entry areas  Entry areas should appear in a consistent position relative to their labels  Provide a quick way to move through the fields in order

10 Chapter 10: Databases32 Designing the Interface  Use scrolling to create multiple screens, if necessary  Provide buttons or other easy-to-use controls for navigating through records  Supply on-screen instructions

10 Chapter 10: Databases33 Designing the Interface

10 Chapter 10: Databases34 Designing Report Templates  Report generators are used to specify the content and format for a database report  A report template contains the outline or general specifications for a report

10 Chapter 10: Databases35 Designing Report Templates  Supply only the information required  Present information in a usable format  Information should be timely  Information should be presented in a clear, unambiguous format  Present information in the format most appropriate for the audience

10 Chapter 10: Databases36 Loading Data  Data can be loaded into a database by: –Using generic data entry tools –Using a customized data entry module  A conversion routine converts the data from its current format into a format that can be automatically incorporated into the new database

10 Chapter 10: Databases37 SQL Basics  Intermediary between the database client software and the database itself

10 Chapter 10: Databases38 SQL Basics

10 Chapter 10: Databases39 Adding Records

10 Chapter 10: Databases40 Searching for Information SELECT AlbumTitle, AlbumCover FROM Albums WHERE ArtistName = ‘Jefferson Airplane’  The AND, OR, and NOT Boolean operators are used to perform complex SQL searches  The use of parentheses indicates the part of the query to perform first

10 Chapter 10: Databases41 Updating Fields UPDATE Albums SET InStock = InStock – 1 WHERE AlbumTitle = ‘G.I. Blues’  Global updates change the data in multiple records simultaneously –Works only for records with similar characteristics

10 Chapter 10: Databases42 Joining Tables  Joining tables in SQL allows you to create relationships between tables

10 Chapter 10: Databases43 Lab Assignment-Create 3 Database Tables  You are a DBA at Wal-Mart Superstore and you need to create three new database tables for all the items you sell in Excel –Divide the store into 3 sections. Create 1 table per worksheet for each section. Name the worksheets after each section you create. –Create all the proper and logical field columns that will be used for each section. –Fill in the first 3 records for each table with random materials found in that section.