Page 1 ISMT E-120 Introduction to Microsoft Access & Relational Databases The Influence of Software...
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Transcript of Page 1 ISMT E-120 Introduction to Microsoft Access & Relational Databases The Influence of Software...
Page 1
ISMT E-120
Introduction to Microsoft Access & Relational Databases
The Influence of Software and Hardware Technologies on Business Productivity
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• The Basics – Database, Query & Entity• Relational Databases• Database Design• Entity Relationship Analysis• Database Objects• Create a Database• Normalization
Introduction to Microsoft Access & Relational Databases
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• The Basics – Database, Query & Entity• Relational Databases• Database Design• Entity Relationship Analysis• Database Objects• Create a Database• Normalization
Introduction to Microsoft Access & Relational Databases
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Database Basics
1. Database is made up of 1 or more tables containing data
2. Tables have fields, also called columns
3. Tables have rows, also called records
4. Record is a set of fields in a row
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Query Basics
• Query means get data from which fields from which rows
• Query EngineoConnects database to a data sourceo Allows us to choose from tables or queries
saved in database• Access
oUse a design grid to create queriesoDrag-and-drop or write SQL
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Entity Basics
• Key concept – types of info in the database
• What are they? o Subject of the databaseo Subject of each tableoNouns (person, place, thing)o Important topicsoUnique representation of a single real-
world object
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Examples of Entities
• Grade Databaseo InstructorsoClasseso Assignmentso Studentso EnrollmentsoResultsoGrades
• Music Collection DatabaseoMusic genresoMusic mediumso Artistso Song Titleso Instrumentso Year recorded
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Introduction to Microsoft Access & Relational Databases
• The Basics – Database, Query & Entity• Relational Databases• Database Design• Entity Relationship Analysis• Database Objects• Create a Database• Normalization
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What is a Relational Database?
• A database is made up of tables• Relationships link tables together• Simple database = 1 subject• Complex database = many subjects• 1 subject = 1 entity per table
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Table Relationships
• Use verbs to describe a relationship between tables/entities/subjects
• Linkages• Types of relationships
one-to-one one-to-many** many-to-many
**Most common and almost always best
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Examples of Relationships
• Instructors Teach Classes• Students Enroll in Classes• Classes Require Assignments• Students Submit Assignments• Students Receive Results
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Introduction to Microsoft Access & Relational Databases
• The Basics – Database, Query & Entity• Relational Databases• Database Design• Entity Relationship Analysis• Database Objects• Create a Database• Normalization
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Design: Understand the Business Application
• Document sequence of steps• Map information flows• Identify decision points• View from user or audience perspective
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Design: Identify Data Elements
Might use:• Manual Input Forms• Reports• Interviews• General Knowledge
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Introduction to Microsoft Access & Relational Databases
• The Basics – Database, Query & Entity• Relational Databases• Database Design• Entity Relationship Analysis• Database Objects• Create a Database• Normalization
Entity Relationship Analysis
1. Identify distinct, relevant entities; name them and identify a primary key
2. Determine relationships between entities – describe them as verbs in whole sentences; create new entities as needed
3. Add appropriate attributes to entities; if an attribute has repeating values, create a new entity with a 1-to-many relationship Page 17
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Introduction to Microsoft Access & Relational Databases
• The Basics – Database, Query & Entity• Relational Databases• Database Design• Entity Relationship Analysis• Database Objects• Create a Database• Normalization
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Tables
• One Table, One Entity/Topic/Subject• Base or reference tables• Made up of fields/attributes• Must have a primary key• Same key in more than one table to link
them – primary key in one table and foreign key in second table
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Queries• Types of Queries
• Select - get data out (view, export …)• Append – add data to existing table• Update - change existing data• Delete - delete data
• SQL does the work
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Forms
• Customary user interface• Base on a table or query• Forms help users to:
o View datao Insert dataoUpdate dataoDelete data
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Creating Forms
• Based on tables• Walk through table one row at a time
• Based on queries• More powerful• Manage data from several tables at once
• Use form wizard or design palette
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Reports
• Presents data in an easy to read, attractive manner
• Can be based on a table or query• Format query results• One query can be used for multiple
reports• One report can be made from multiple
queries
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Creating Reports
• Can be based on tables• Can be based on queries
• More powerful• Link several tables at once• Select fields• Add calculations, etc.
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Macros
• Stored Sequence of Operations• Can be executed any time• Easy to use interface to create them
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Introduction to Microsoft Access & Relational Databases
• The Basics – Database, Query & Entity• Relational Databases• Database Design• Entity Relationship Analysis• Database Objects• Create a Database• Normalization
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Create An Access Database
• What’s the topic/subject/entity of the database?
• Define Tables and Keys
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Create An Access Database
• Establish Relationships– Link All Tables– Database Tools Relationships…– Relationship Properties– Relationships Carry Over to Queries
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Create An Access Database
• Create queries for use with forms and reports
• Develop forms• Write reports
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Introduction to Microsoft Access & Relational Databases
• The Basics – Database, Query & Entity• Relational Databases• Database Design• Entity Relationship Analysis• Database Objects• Create a Database• Normalization
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What is Normalization?
• Process to Eliminate Redundancy• Group Data Items into Manageable
Collections• Verify Completeness of Data
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Benefits of Normalization
• Easier to Maintain Information• Easier to Query Database• Extensible Design• Promotes Data Integrity
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Normalization: Step 1• List Every Data Item in One Table
• Columns/fields• Rows/records
• 1 Cell = 1 Piece of Data• Add Duplicate Information as Needed• Find or Create a Primary Key
• A field or combination of fields uniquely identifying each row
• This is First Normal Form
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Normalization: Step 2
• Which Keys Determine Which Fields?• Functional dependencies• One key value determines one field value
• May be > 1 Set of Keys• Break Into Separate Tables According to
Functional Dependencies• This is Second Normal Form
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Normalization: Step 3
• Look for Functional Dependencies Among Non-Key Fields
• Remove Any Dependent Non-Key Fields
• Make Sure No Loss of Information• i.e., fields should be in some other table
• Third Normal Form