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Chapter 1 Overview of Database Concepts Jason C.H. Chen, Ph.D. Professor of MIS School of Business, Gonzaga University Spokane, WA 99258 USA [email protected] Dr. Chen, Business Database Systems Objectives • Define database terms • Identify the purpose of a database management system (DBMS) • Explain database design using entity-relationship models and normalization • Explain the purpose of a Structured Query Language (SQL) • Understand how this textbook’s topics are sequenced and how the two sample databases are used Dr. Chen, Business Database Systems 2 What is Information ? DATA INFORMATION Information is refined data. Dr. Chen, Business Database Systems Data vs. Information • Users really want is – Information What users can learn from the data how to satisfy their best customers how to allocate their resources most efficiently, how to minimize losses Dr. Chen, Business Database Systems 4 Objectives of the MIS Deliver the right information to the right people, at the right time, with the right form. Ultimately, MIS should improve the workers’ productivity. Dr. Chen, Business Database Systems who has what information about whom and when, where, and how will all be decided in the process of building an information system. 5 A Relationship Between the Organization and the DataBase Organizational IS Resources: 1. Hardware 2. Software 3. Data 4. Procedures 5. People DataBase Management Systems Old State Activities Picture Or Model Events New State Transactions (Add, modify, delete, …) D.B. Correspond with the processing of the events Information must be: 1. Time: Timely, 2. Content: Accurate, relevant, and verifiable. 3. Form: Presented in a useable form. User Dr. Chen, Business Database Systems TM 0-6 Questions • Is MS/Access or Oracle (SQL/Server or IBM DB2) a data base? • Why don’t we just create a “huge” data file containing all fields (columns)? – Have you ever created a database (with many applications) with only one “huge” data file containing all fields (columns)? Dr. Chen, Business Database Systems 7 Traditional File Processing Approach • Traditional File Processing – An application uses one specialized file. For example, purchase order processing application uses data about supplier and products, while an order-taking application uses data about customer, products and orders. • Problems: – Data dependence: data structures are tightly coupled with applications. In other words, we prefer data independence. – Data redundancy: same data are repeatedly saved for different applications. – Other problems Dr. Chen, Business Database Systems 8 Types of Data Processing • Two types of data processing – File-based (traditional) data processing • applications developed by Java – Data-based data processing • applications developed by Oracle or MS/Access) Dr. Chen, Business Database Systems 9 Three file processing systems at a Furniture Company Duplicate Data Dr. Chen, Business Database Systems What is the main problem in the company’s processing systems? Disadvantages of File Processing • Program-Data Dependence – All programs maintain metadata for each file they use • Data Redundancy (Duplication of data) – Different systems/programs have separate copies of the same data • Limited Data Sharing – No centralized control of data • Lengthy Development Times – Programmers must design their own file formats • Excessive Program Maintenance – 80% of of information systems budget Dr. Chen, Business Database Systems 11 Database Management System Application #1 Application #2 Application #3 DBMS Database containing centralized shared data DBMS manages data resources like an operating system manages hardware resources What are the advantages of employing Data-based Data Processing? Dr. Chen, Business Database Systems Traditional File Processing Applications Purchasing System Data Files Product Supplier Name, item#, description... Sales order processing system Dr. Chen, Business Database Systems Name, item#, description... Sales rep Product Database Management Systems D a tab a s e P u rch a sing Sys te m D a ta b a s e M an a g e m e n t Sys te m s Produ ct Sales rep S a le s o rd er pro ce s s in g sys te m Dr. Chen, Business Database Systems Sup plie r Database Terminology • Database – an organized collection of logically related data files • Database management system (DBMS) – software used to create and interact with the database Dr. Chen, Business Database Systems 15 Database Components • Character – Basic unit of data – Can be a letter, number, or special symbol • Field – A group of related characters – Represents an attribute or characteristic of an entity – Corresponds to a column in the physical database • Record – A collection of fields for one specific entity – Corresponds to a row in the physical database • File – A group of records about the same type of entity Dr. Chen, Business Database Systems 16 Relational Databases • Data is organized in tables – Columns (fields) represent different data categories – Rows (records) contain actual data values Dr. Chen, Business Database Systems 17 Database Example Dr. Chen, Business Database Systems 18 Components Example Dr. Chen, Business Database Systems Relational Database Terms • Entity: an object about which you want to store data • Table, column, row – Flat file, attribute (or field), record • Relationships: links that show how different records are related • Key Fields: establish relationships among records in different tables • Five main types of key fields: – – – – – primary keys candidate keys surrogate keys foreign keys composite keys Dr. Chen, Business Database Systems 20 Primary Keys vs. Candidate Keys • Primary key – Value must be unique for each record – Serves to identify the record – Present in every record – Can’t be NULL – Should be numeric • Candidate key – Any field that could be used as the primary key – Should be a unique, unchanging numeric field Dr. Chen, Business Database Systems 21 Surrogate Keys • Surrogate key: created to be the record’s primary key identifier when no suitable primary key exists • Surrogate key has no real relationship to the record to which it is assigned, other than to identify the record uniquely • Developers configure the database to generate surrogate key values automatically • In an Oracle database, you can automatically generate surrogate key values using a sequence • Surrogate keys are always numerical fields, because the database generates surrogate key values automatically by incrementing the previous value by one Dr. Chen, Business Database Systems 22 Foreign Keys • Foreign key: a field in a table that is a primary key in another table • Foreign key creates a relationship between the two tables • Foreign key value must exist in the table where it is a primary key Dr. Chen, Business Database Systems 23 Composite Key • Composite key: a unique key that you create by combining two or more fields • Usually comprised of fields that are primary keys in other tables Composite Key ORDER_ID PRODUCT_ID ORDER_QUANTITY 100 1 2 100 2 2 200 2 2 200 1 1 Dr. Chen, Business Database Systems 24 Database Management System • 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 Dr. Chen, Business Database Systems 25 Client/Server Database Management Systems • Client/server database – Takes advantage of distributed processing and networked computers by distributing processing across multiple computers – DBMS server process runs on one workstation, and the database applications run on separate client workstations across the network – Preferred for database applications that retrieve and manipulate small amounts of data from databases containing large numbers of records because they minimize network traffic and improve response times • Organizations generally use a client/server database if the database will have more than 10 simultaneous users and if the database is mission critical Dr. Chen, Business Database Systems 26 The Oracle11g Client/Server Database • Oracle11g is the latest release of Oracle Corporation’s relational database management system • All Oracle server- and client-side programs use Oracle Net, a utility that enables the network communication between the client and the server Dr. Chen, Business Database Systems DATABASE TRENDS Linking Internal Databases to the Web N Dr. Chen, Business Database Systems 28 Web-Based Client/Server Database Architecture 2. Request for data-based Web page 1. Request for data-based Web page Network 8. Data-based Web page Web Browser 3. Data query 6. Retrieved data 7. Data-based Web page 4. Data query Web server 5. Retrieved data Legend Communications Between Web browser And Web server Database Server Dr. Chen, Business Database Systems Communications Between Web server And database server 29 System Response Time Depends on ... • the speed of the network • the size of the database • the way the database is used … • a personal database running on a server might handle 10 users making database transactions at the same time before becoming overloaded. Dr. Chen, Business Database Systems 30 Advantages of Client/Server Database Management Systems Handling server and client failures Processing transactions Handling high data volumes Providing security Servicing multiple simultaneous users Dr. Chen, Business Database Systems 31 SQL, SQL*Plus, and PL/SQL Language or Tool Description SQL A command language for communication with the Oracle 10/11Server from any tool or application. Oracle SQL contains many extensions. An Oracle tool that recognizes and submits SQL and PL/SQL statements to the Server for execution and contains its own command language. An Oracle Procedural Language for writing application logic and manipulating data outside the database. SQL*Plus PL/SQL Terminal Buffer SQL and PL/SQL Scripts Dr. Chen, Business Database Systems SQL*Plus Server Design Principles • To avoid creating tables that contain redundant data, group related items that describe a single entity together in a common table • Do not create tables that duplicate values many times in different rows • When creating a database and inserting data values, you must specify the data type for each column • Recall that primary key fields should use a number data type to avoid typographical, punctuation, and case variation errors Dr. Chen, Business Database Systems 33 Database Design • Systems Development Life Cycle (SDLC) • Entity-relationship model (E-R model) • Normalization Dr. Chen, Business Database Systems 34 Systems Development Life Cycle Understand the Business Problem or Opportunity Develop an Information System Solution Systems Investigation (Definition) Product: Feasibility Study Systems Analysis Product: Functional Requirements Systems Design Product: System Specifications Implement the Information System Solution Systems Implementation Product: Operational System Systems Maintenance Product: Improved System Dr. Chen, Business Database Systems Systems Development Life Cycle (SDLC) • Systems investigation – understanding the problem • Systems analysis – understanding the solution • Systems design – creating the logical and physical components • Systems implementation – placing completed system into operation – including integration, testing and deployment • Systems maintenance and review – evaluating the implemented system Dr. Chen, Business Database Systems 36 Data Models • A data model is a collection of concepts for describing data. • Three database models – Hierarchical – Network – Relational CUSTOMER Dr. Chen, Business Database Systems ORDER 37 Entity-Relationship Model (E-R Model) • Used to depict the relationship that exists among entities • The following relationships can be included in an E-R model: – One-to-one – One-to-many – Many-to-many Dr. Chen, Business Database Systems E-R Model Notation Examples Figure 1-3 E-R Model notation examples Please note that the name of entity should be singular even it contains multiple instances Dr. Chen, Business Database Systems 39 Figure 1-5 JustLee Books’ table structures after normalization Dr. Chen, Business Database Systems One-to-One Relationship • Each occurrence of data in one entity is represented by only one occurrence of data in the other entity • Example: Each order has just one invoice and each invoice is assigned to just one order ORDER Dr. Chen, Business Database Systems INVOICE 41 One-to-Many Relationship • Each occurrence of data in one entity can be represented by many occurrences of the data in the other entity • Example: A class has only one instructor, but each instructor can teach many classes Class Dr. Chen, Business Database Systems Instructor 42 Many-to-Many Relationship • Data can have multiple occurrences in both entities • Example: A student can take many classes, and each class is composed of many students • Can not be included in the physical database Class Dr. Chen, Business Database Systems Student 43 JustLee Example E-R Model Dr. Chen, Business Database Systems 44 Installing Personal Oracle11g • I created a “Discussion Questions” on the Bb for you to share (or post question) your experience on installation of Oracle 11g. Please participate and it will be also your part of class performance. • • Please note that if your computer with 64-bit operating system such as Windows 7, you can’t use the DVD to install Oracle since it is for 32-bit OS. Rather you need to download 64-bit Oracle 11g from the Oracle site (www.oracle.com) or type in keyword search of “Oracle 11g download”. Dr. Chen, Business Database Systems 45 Q: Can we create/enter the data base on the following table immediately? BOOKS table Publication Date Cost Retail Category Publisher Contact Author Database Implementation 04-JUN-03 31.40 55.95 Computer American Publishing Davidson T.Peterson 8843172113 Database Implementation 04-JUN-03 31.40 55.95 Computer American Publishing Davidson J.Austin 8843172113 Database Implementation 04-JUN-03 31.40 55.95 Computer American Publishing Davidson J.Adams 1915762492 Handcranked Computers 21-JUN-05 21.80 25.00 Computer Amercian Publishing Davidson W.White 1915762492 Handcranked Computers 21-JUN-05 21.80 25.00 Computer Amercian Publishing Davidson L.White 6522489652 Meaningful Accounting 25-MAY-08 41.60 85.00 Accounting Articulate Publishing Brown M.Kane 6522489652 Meaningful Accounting 25-MAY-08 41.60 85.00 Accounting Articulate Publishing Brown S. Little ISBN Title 8843172113 Dr. Chen, Business Database Systems Database Normalization • Purposes – design a reliable and stable data bases – increase data integrity (reduce or control data redundancy) • Processes – determines required tables and columns for each table – multistep process Dr. Chen, Business Database Systems 47 Problem Solving for Modeling a Database Project Study and Analyze w/Team Business Problem ??? IMPLEMENTATION Dr. Chen, Business Database Systems Problem Solving for Modeling a Database Project Study and Analyze w/Team Business Problem User interview & Integrated Model ER or other Model Normalization Normalization (3NF) IMPLEMENTATION Dr. Chen, Business Database Systems Well-Structured Relations • A relation that contains minimal data redundancy and allows users to insert, delete, and update rows without causing data inconsistencies • Goal is to avoid (minimize) anomalies – Insertion Anomaly – adding new rows forces user to create duplicate data – Deletion Anomaly – deleting rows may cause a loss of data that would be needed for other future rows – Modification Anomaly – changing data in a row forces changes to other rows because of duplication General rule of thumb: a table should not pertain to more than one entity type Dr. Chen, Business Database Systems 50 Functional Dependencies and Keys • Functional Dependency: The value of one attribute (the determinant) determines the value of another attribute. • Candidate Key – A unique identifier. One of the candidate keys will become the primary key • E.g. perhaps there is both credit card number and SS# in a table…in this case both are candidate keys – Each non-key field is functionally dependent on every candidate key Figure 5-9 Dr. Chen, Business Database Systems 51 Database Normalization (continued) • Data redundancy – refers to having the same data in different places within a database • Data anomalies – refers to data inconsistencies – Insertion anomaly – Deletion anomaly – Modification anomaly Dr. Chen, Business Database Systems Unnormalized Data • Contains repeating groups in the Author column in the BOOKS table Dr. Chen, Business Database Systems Figure: 5-22 Steps in normalization Table with Repeating Group attributes First normal form (1NF) Second normal form(2NF) Third normal form (3NF) Boyce-Codd normal form (BC-NF) Fourth normal Form (4NF) Fifth normal form (5NF) Dr. Chen, Business Database Systems Remove Repeating Group Attributes Remove … Remove … Remove remaining anomalies resulting from multiple candidate keys Remove Multivalued Dependencies Remove Remaining Anomalies First-Normal Form (1NF) • Primary key (pk) is identified • Repeating groups are eliminated • Every attribute value is atomic (singledvalue) Dr. Chen, Business Database Systems 55 First-Normal Form (1NF) (continued) • ISBN and Author columns together create a composite primary key Dr. Chen, Business Database Systems 1NF: ISBN and Author fields together create a composite primary key Q: What fields are dependent on ISBN alone ? Publication Date Cost Retail Category Publisher Contact Author Database Implementation 04-JUN-03 31.40 55.95 Computer American Publishing Davidson T.Peterson 8843172113 Database Implementation 04-JUN-03 31.40 55.95 Computer American Publishing Davidson J.Austin 8843172113 Database Implementation 04-JUN-03 31.40 55.95 Computer American Publishing Davidson J.Adams 1915762492 Handcranked Computers 21-JUN-05 21.80 25.00 Computer Amercian Publishing Davidson W.White 1915762492 Handcranked Computers 21-JUN-05 21.80 25.00 Computer Amercian Publishing Davidson L.White 6522489652 Meaningful Accounting 25-MAY-08 41.60 85.00 Accounting Articulate Publishing Brown M.Kane 6522489652 Meaningful Accounting 25-MAY-08 41.60 85.00 Accounting Articulate Publishing Brown S. Little ISBN Title 8843172113 Dr. Chen, Business Database Systems Composite Primary Key • More than one field (column) is required to uniquely identify a record (row). • Can lead to partial dependency – a field is only dependent on a portion of the primary key Dr. Chen, Business Database Systems 58 Second-Normal Form (2NF) • 1NF and every non-key attribute is fully functionally dependent on the primary key. • Partial dependency must be eliminated – Break the composite primary key into two parts, each part representing a separate table – Every non-key attribute must be defined by the entire key (either a single PK or a CK), not by only part of the key Dr. Chen, Business Database Systems 59 Second-Normal Form (2NF) (continued) • BOOKS table in 2NF ISBN Author Publication Date Cost Retail Category Publisher Contact 8843172113 T.Peterson Database Implementation 04-JUN-03 31.40 55.95 Computer American Publishing Davidson 8843172113 J.Austin 1915762492 Handcranked Computers 21-JUN-05 21.80 25.00 Computer American Publishing Davidson 8843172113 J.Adams 1915762492 W.White 6522489652 Meaningful Accounting 25-MAY-08 41.60 85.00 Accounting Articulate Publishing Brown 1915762492 L.White 6522489652 M.Kane 6522489652 60 S. Little ISBN Title 8843172113 Dr. Chen, Business Database Systems 1NF: ISBN and Author fields together create a composite primary key Q: What fields are dependent on ISBN alone ? Publication Date Cost Retail Category Publisher Contact Author Database Implementation 04-JUN-03 31.40 55.95 Computer American Publishing Davidson T.Peterson 8843172113 Database Implementation 04-JUN-03 31.40 55.95 Computer American Publishing Davidson J.Austin 8843172113 Database Implementation 04-JUN-03 31.40 55.95 Computer American Publishing Davidson J.Adams 1915762492 Handcranked Computers 21-JUN-05 21.80 25.00 Computer Amercian Publishing Davidson W.White 1915762492 Handcranked Computers 21-JUN-05 21.80 25.00 Computer Amercian Publishing Davidson L.White 6522489652 Meaningful Accounting 25-MAY-08 41.60 85.00 Accounting Articulate Publishing Brown M.Kane 6522489652 Meaningful Accounting 25-MAY-08 41.60 85.00 Accounting Articulate Publishing Brown S. Little ISBN Title 8843172113 Dr. Chen, Business Database Systems Fig: A Process from 1NF to 2NF Dependency on entire primary key (ISBN & Author) ISBN Title Publication Date Cost Retail Category Publisher Contact Author Dependency on partial primary key (ISBN) Publication Date Cost Retail Category Publisher Contact Author Database Implementation 04-JUN-03 31.40 55.95 Computer American Publishing Davidson T.Peterson 8843172113 Database Implementation 04-JUN-03 31.40 55.95 Computer American Publishing Davidson J.Austin 8843172113 Database Implementation 04-JUN-03 31.40 55.95 Computer American Publishing Davidson J.Adams 1915762492 Handcranked Computers 21-JUN-05 21.80 25.00 Computer Amercian Publishing Davidson W.White 1915762492 Handcranked Computers 21-JUN-05 21.80 25.00 Computer Amercian Publishing Davidson L.White 6522489652 Meaningful Accounting 25-MAY-08 41.60 85.00 Accounting Articulate Publishing Brown M.Kane 6522489652 Meaningful Accounting 25-MAY-08 41.60 85.00 Accounting Articulate Publishing Brown S. Little ISBN Title 8843172113 Dr. Chen, Business Database Systems Fig: A Process from1NF to 2NF Dependency on entire primary key (ISBN & Author) ISBN Title Publication Date Cost Retail Category Publisher Contact Author Dependency on partial primary key (ISBN) ISBN & Author Title, Publication Date, Cost … ISBN Title, Publication Date, Cost … Therefore, NOT in 2nd Normal Form!! Dr. Chen, Business Database Systems Fig: A Process from 1NF to 2NF Dependency on entire primary key (ISBN & Author) ISBN Title Publication Date Cost Retail Category Publisher Contact Author Dependency on partial primary key (ISBN) ISBN Title Publication Cost Retail Category Publisher Contact Date ISBN Author Dr. Chen, Business Database Systems Fig: A Process from 1NF to 2NF Publication Date Cost Retail Category Publisher Contact Author Database Implementation 04-JUN-03 31.40 55.95 Computer American Publishing Davidson T.Peterson 8843172113 Database Implementation 04-JUN-03 31.40 55.95 Computer American Publishing Davidson J.Austin 8843172113 Database Implementation 04-JUN-03 31.40 55.95 Computer American Publishing Davidson J.Adams 1915762492 Handcranked Computers 21-JUN-05 21.80 25.00 Computer Amercian Publishing Davidson W.White 1915762492 Handcranked Computers 21-JUN-05 21.80 25.00 Computer Amercian Publishing Davidson L.White 6522489652 Meaningful Accounting 25-MAY-08 41.60 85.00 Accounting Articulate Publishing Brown M.Kane 6522489652 Meaningful Accounting 25-MAY-08 41.60 85.00 Accounting Articulate Publishing Brown S. Little ISBN Title 8843172113 ISBN Author Publication Date Cost Retail Category Publisher Contact 8843172113 T.Peterson Database Implementation 04-JUN-03 31.40 55.95 Computer American Publishing Davidson 8843172113 J.Austin 1915762492 Handcranked Computers 21-JUN-05 21.80 25.00 Computer American Publishing Davidson 8843172113 J.Adams 1915762492 W.White 6522489652 Meaningful Accounting 25-MAY-08 41.60 85.00 Accounting Articulate Publishing Brown 1915762492 L.White 6522489652 M.Kane 6522489652 S. Little ISBN Title 8843172113 Dr. Chen, Business Database Systems Figure 1-5 JustLee Books’ table structures after normalization Dr. Chen, Business Database Systems Figure: 5-22 Steps in normalization Table with Repeating Group attributes Remove Repeating Group Attributes First normal form (1NF) Second normal form(2NF) Third normal form (3NF) Boyce-Codd normal form (BC-NF) Fourth normal Form (4NF) Fifth normal form (5NF) Dr. Chen, Business Database Systems Remove Partial Dependencies Remove Transitive Dependencies Remove remaining anomalies resulting from multiple candidate keys Remove Multivalued Dependencies Remove Remaining Anomalies Third Normal Form (3NF) • Transitive dependency must be eliminated – 2NF and transitive dependencies (functional dependency between non-key attributes) must be eliminated Dr. Chen, Business Database Systems 68 Fig: A Process from 1NF to 2NF Dependency on entire primary key (ISBN & Author) ISBN Title Publication Date Cost Retail Category Publisher Contact Author Dependency on partial primary key (ISBN) Is it in the 3NF? ISBN Title Publication Cost Retail Category Publisher Contact Date ISBN Author Dr. Chen, Business Database Systems Fig: A Process from 2NF to 3NF All non-key fields are dependent on pk (ISBN) ISBN Title Publication Cost Retail Category Publisher Contact Date ISBN Title ISBN Publication Date … ISBN Category ISBN Publisher ISBN Contact and Category Contact All this is OK (2nd NF) Dr. Chen, Business Database Systems a non-key field is dep. on another non-key field BUT ISBN Category Contact implies ISBN Contact Transitive dependency (not in 3rd NF) Fig: A Process from 2NF to 3NF ISBN Title ISBN Title Publication Cost Retail Category Publisher Contact Date Publication Cost Retail Category Publisher Date Category Dr. Chen, Business Database Systems Contact Third-Normal Form (3NF) • Publisher contact name has been removed Publication Date Cost Retail Category Publisher Database Implementation 04-JUN-03 31.40 55.95 Computer American Publishing 1915762492 Handcranked Computers 21-JUN-05 21.80 25.00 Computer American Publishing 6522489652 Meaningful Accounting 25-MAY-08 41.60 85.00 Accounting Articulate Publishing ISBN Title 8843172113 TABLE 1-5 The BOOKS Table in 3NF Dr. Chen, Business Database Systems Category Contact Computer Davidson Accounting Brown We might further create a look up table for “Category” (see Table 1-6, p.12) Fig: A Process from 2NF to 3NF Publication Date Cost Retail Category Publisher Contact Database Implementation 04-JUN-03 31.40 55.95 Computer American Publishing Davidson 1915762492 Handcranked Computers 21-JUN-05 21.80 25.00 Computer American Publishing Davidson 6522489652 Meaningful Accounting 25-MAY-08 41.60 85.00 Accounting Articulate Publishin g Brown Publication Date Cost Retail Category Publisher ISBN Title 8843172113 ISBN Title 8843172113 Database Implementation 04-JUN-03 31.40 55.95 Computer American Publishing 1915762492 Handcranked Computers 21-JUN-05 21.80 25.00 Computer American Publishing 6522489652 Meaningful Accounting 25-MAY-08 41.60 85.00 Accounting Articulate Publishing Dr. Chen, Business Database Systems Category Contact Computer Davidson Accounting Brown Processes from 1NF 2NF 3NF Dependency on entire primary key (ISBN & Author) ISBN Title Publication Date Cost Retail Category Publisher Contact Author Dependency on partial primary key (ISBN) (remove partial dependency) ISBN Title Publication Cost Retail Category Publisher Contact Date ISBN Author (remove transitive dependency) ISBN Title Publication Cost Retail Category Publisher Date Q: Finally, how many tables on the 3NF? Dr. Chen, Business Database Systems Category Contact Q: How many tables on the 3NF? ISBN Title Publication Date Cost Retail Category Publisher Contact Author Answer: Three tables. What are they? BOOK_AUTHOR BOOKS ISBN Title Publication Cost Retail Category Publisher Date Note that You can’t do any implementation until you transform a table into 3NF (with more tables produced) Dr. Chen, Business Database Systems ISBN Author CATEGORY_CONTACT Category Contact Processes from 1NF 2NF 3NF Publication Date Cost Retail Category Publisher Contact Author Database Implementation 04-JUN-03 31.40 55.95 Computer American Publishing Davidson T.Peterson 8843172113 Database Implementation 04-JUN-03 31.40 55.95 Computer American Publishing Davidson J.Austin 8843172113 Database Implementation 04-JUN-03 31.40 55.95 Computer American Publishing Davidson J.Adams 1915762492 Handcranked Computers 21-JUN-05 21.80 25.00 Computer Amercian Publishing Davidson W.White 1915762492 Handcranked Computers 21-JUN-05 21.80 25.00 Computer Amercian Publishing Davidson L.White 6522489652 Meaningful Accounting 25-MAY-08 41.60 85.00 Accounting Articulate Publishing Brown M.Kane 6522489652 Meaningful Accounting 25-MAY-08 41.60 85.00 Accounting Articulate Publishing Brown S. Little ISBN Title 8843172113 Publication Date Cost Retail Category Publisher ISBN Author Database Implementation 04-JUN-03 31.40 55.95 Computer American Publishing 8843172113 T.Peterson 8843172113 J.Austin Handcranked Computers 21-JUN-05 21.80 25.00 Computer American Publishing 8843172113 J.Adams Meaningful Accounting 25-MAY-08 1915762492 W.White 1915762492 L.White 6522489652 M.Kane 6522489652 S. Little ISBN Title 8843172113 1915762492 6522489652 41.60 85.00 Accounting Articulate Publishing fk(foreign key) Category Code Category Category Contact 10 Computer Computer Davidson 50 Accounting Accounting Brown Dr. Chen, Business Database Systems We will learn all detailed processes in the main text (ch.4) Figure: 5-22 Steps in normalization Table with Repeating Group attributes Remove Repeating Group Attributes First normal form (1NF) Second normal form(2NF) Third normal form (3NF) Boyce-Codd normal form (BC-NF) Fourth normal Form (4NF) Fifth normal form (5NF) Dr. Chen, Business Database Systems Remove Partial Dependencies Remove Transitive Dependencies Remove remaining anomalies resulting from multiple candidate keys Remove Multivalued Dependencies Remove Remaining Anomalies Summary of Normalization Steps • 1NF: eliminate repeating groups, identify the primary key • 2NF: table is in 1NF, and partial dependencies are eliminated • 3NF: table is in 2NF, and transitive dependencies are eliminated Dr. Chen, Business Database Systems 78 Figure: 5-22 Steps in normalization Table with Repeating Group attributes Remove Repeating Group Attributes First normal form (1NF) Second normal form(2NF) Third normal form (3NF) Boyce-Codd normal form (BC-NF) Fourth normal Form (4NF) Fifth normal form (5NF) Dr. Chen, Business Database Systems Remove Partial Dependencies Remove Transitive Dependencies Remove remaining anomalies resulting from multiple candidate keys Remove Multivalued Dependencies Remove Remaining Anomalies Relating Tables within the Database • Once tables are normalized, make certain tables are linked • Tables are linked through a common field • A common field is usually a primary key in one table and a foreign key in the other table Dr. Chen, Business Database Systems 80 Category_Contact Category Contact Dr. Chen, Business Database Systems Lookup Table • Common reference for descriptive data tables referenced in a foreign key fk(foreign key) Dr. Chen, Business Database Systems Category Code Category 10 Computer 50 Accounting 82 Structured Query Language (SQL) • Data sublanguage • Used to: – – – – Create or modify tables Add data to tables Edit data in tables Retrieve data from tables • ANSI and ISO standards Dr. Chen, Business Database Systems 83 Databases Used in this Textbook – JustLee Books Database • Assumptions – No back orders or partial shipments – Only U.S. addresses – Completed orders are transferred to the annual SALES table at the end of each month to enable faster processing on the ORDERS table Dr. Chen, Business Database Systems 84 Topic Sequence • The first half of the text will focus on creating a database • The second half of the text will focus on querying or retrieving data from a database Dr. Chen, Business Database Systems 85 Summary • A DBMS is used to create and maintain a database • A database is composed of a group of interrelated tables • A file is a group of related records; a file is also called a table in the physical database • A record is a group of related fields regarding one specific entity; a record is also called a row • A common field is used to join data contained in different tables • A primary key is used to uniquely identify each record • A foreign key is a common field that exists between two tables but is also a primary key in one of the tables • A lookup table is a common term for a table referenced in a foreign key • A Structured Query Language (SQL) is a data sublanguage that navigates the data stored within a database’s tables Dr. Chen, Business Database Systems 86 Summary (continued) • A record is considered unnormalized if it contains repeating groups • A record is in first-normal form (1NF) if no repeating groups exist and it has a primary key • Second-normal form (2NF) is achieved if the record is in 1NF and has no partial dependencies • After a record is in 2NF and all transitive dependencies have been removed, then it is in third-normal form (3NF), which is generally sufficient for most databases Dr. Chen, Business Database Systems 87 Homework: Transform it into 3NF SALES relation with simple data SALES Cust_ID Name Salesperson Region 8023 Anderson 101 South 9167 Bancroft 102 West 7924 Hobbs 101 South 6837 Tucker 103 East 8596 Eckersley 102 West 7018 Arnold 104 North Dr. Chen, Business Database Systems