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Published byPoppy Rich Modified over 5 years ago
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Why Study Databases? Databases have incredible value to businesses.
Very important technology for supporting operations. Vastly superior to file processing systems Businesses cannot survive without quality data about their internal operations and external environment.
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Foundation Data Concepts
Abstract Concepts Entity – person, place, object or event – stored as a record or a table row Attribute – characteristic of an entity – stored as field or table column
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Foundation Data Concepts
Large Database Concepts Database – a collection of related tables Tables – a collection of related records – collection of related entities Record – collection of fields (table row) –represents an entity Field – collection of characters (table column) – represents an attribute Character – single alphabetic, numeric or other symbol Small
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Fields Characters “B R E I M E R” form a field
A field is an attribute of an entity Last Name Breimer
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Records A bunch of fields form a record A record is an entity
First Name Eric Last Name Breimer Sex Yes Weight 263
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Tables A bunch of records forms a table
A table is a group of related entities First Name Last Name Sex Age Eric Breimer M 30 Jeff Albert 22 Jackie Pizzo F 21
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Databases A bunch of tables form a database
Databases A bunch of tables form a database A database can represent a single business or an entire market Order Table Customer Table Product Table
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Databases But, databases are not just a bunch of tables
But, databases are not just a bunch of tables A database also includes relationships between the different tables Orders OID CID PID Quantity 001 508 199 500,000 002 201 2 003 510 1 Customers CID FName LName Address 508 Eric Breimer ... 509 Andrew Zych 510 Greg Smith Products PID Description Cost 199 Viagra $45.99 200 Tooth Paste $2.58 201 Hair Gel $5.99
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Relationships & Queries in Databases
Chapter 5 Relationships & Queries in Databases
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Types of Relationships
One to One Examples? Analysis Technique Consider ThingA and ThingB Can ThingA be related to more than one ThingB? Can ThingB be related to more than one ThingA? If the two answers are NO, then it is a one to one relationship. ThingA ThingB Relationship Man Woman Married
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Types of Relationships
Faculty Student One to Many Examples? Analysis Technique Consider ThingA and ThingB Can ThingA be related to more than one ThingB? Can ThingB be related to more than one ThingA? If only one answer is yes, then you have a one to many relationship Advises Get Advisement
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Types of Relationships
student takes course Course Student Many to Many Examples? Analysis Technique Consider ThingA and ThingB Can ThingA be related to more than one ThingB? Can ThingB be related to more than one ThingA? If the answers are yes and yes, then the relationship is many to many. course has a student
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How to Model Relationships
Orders OID CID PID Quantity 001 508 199 500,000 002 201 2 003 510 1 Customers CID FName LName Address 508 Eric Breimer ... 509 Andrew Zych 510 Greg Smith Products PID Description Cost 199 Viagra $45.99 200 Tooth Paste $2.58 201 Hair Gel $5.99
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Find the name and hire date of the manager working on the sales manual project
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Traditional File Processing Sucks
Data is organized, stored, and processed in independent files of data records
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Problems of File Processing
Data Redundancy – duplicate data requires update to many files Lack of Integration – data stored in separate files hard to combine data Data Dependence – changing the file format requires changing the program…
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Database Management Approach
Consolidates data records into one CENTRAL database that can be accessed by many different application programs.
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Database Management Software (DBMS)
Definition: Software that controls the creation, maintenance, and use of databases
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DBMS Software Components
Database Definition Language and graphical tools to define entities, relationships, integrity constraints, and authorization rights Application Development Graphical tools to develop menus, data entry forms, and reports
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DBMS Software Components
Transaction Processing Controls to prevent interference from simultaneous users and Controls to recover lost data after a failure Database Tuning Tools to monitor and improve database performance
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Database Interrogation
Definition: Capability of a DBMS to report information from the database in response to end users’ requests Query Language – allows easy, immediate access to ad hoc data requests Report Generator - allows quick, easy specification of a report format for information users have requested
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Natural Language vs. SQL Queries
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Schemas Schema - A description of the database
Subschema – describes a subset of the database and which users have access to this subset
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Data Definition Language
Language Used to describe Schemas and Subschemas Describes relationships between different data Provides a Logical view of the data
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Data Dictionary Entry A more detailed description of the data in a database Specifies data types and ranges Assists programmers in understanding the data
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Physical vs. Logical DBMS concentrate on Physical access to the underlying tables Concurrency control Query’s Creating/deleting tables
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Physical vs. Logical MIS systems are (Logically) interface with a DBMS
monthly reports charts automated inquiries
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Application Development
Today, even non-technical staff can use tools to build little programs that use a database. Database Management Systems have all kinds of tools to develop custom application programs and interfaces. Example: The College’s MIS (Banner) is actually an application built on top of a Oracle Database.
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