Clearwater+and+Northwoods+Data+Models+and+Requirements+for+SQL+DDL+Practice

Clearwater+and+Northwoods+Data+Models+and+Requirements+for+SQL+DDL+Practice

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A Guide to Oracle9 i 1 Client/Server Databases and the Oracle9 i Relational Database Chapter 1
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A Guide to Oracle9 i 2 Objectives Develop an understanding of the purpose of database systems Become familiar with the structure of a relational database and review relational database concepts and terms Explore the differences between personal databases and client/server databases Learn about the Clearwater Traders sales order database, the Northwoods University student registration database, and the Software Experts project management database
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A Guide to Oracle9 i 3 Before Databases Information was kept in files: Each field describes one piece of information about student Fields are separated by commas – A record is a collection of related fields – Each record is a separate line
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A Guide to Oracle9 i 4 Problems with Files Proliferation of data management programs to deal with different file formats Redundant data stored in files Data files may contain inconsistent data
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A Guide to Oracle9 i 5 Database Approach Database stores all organizational data in a central location Good database design eliminates redundant data to reduce the possibility of inconsistent data Single application called the database management system (DBMS) performs all routine data handling operations Database administrator ( DBA): person responsible for installing, administering, and maintaining the database
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A Guide to Oracle9 i 6 Early Databases – Hierarchical Structure
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A Guide to Oracle9 i 7 Relational Databases
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A Guide to Oracle9 i 8 Relational Database Terms Entity : an object about which you want to store data 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
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A Guide to Oracle9 i 9 Primary 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
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A Guide to Oracle9 i 10 Candidate Keys Candidate key Any field that could be used as the primary key Should be a unique, unchanging numeric field
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i 11 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
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This note was uploaded on 04/01/2012 for the course MIS 245 taught by Professor Havelka during the Spring '12 term at Miami University.

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Clearwater+and+Northwoods+Data+Models+and+Requirements+for+SQL+DDL+Practice

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