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Succeeding in Business with Microsoft Access 2013 2
Chapter Introduction
• Gathering data/planning a database design– Discovery phase includes:• Gathering all existing data • Researching missing and incomplete data• Talking with users about data output needs
– Subsequent steps in process include:• Putting data into groups called tables• Identifying unique values for each record in those
tables • Designing database to produce desired output
Succeeding in Business with Microsoft Access 2013 5
Level 1 Objectives: Examining Existing and Missing Sources of Data
• Discover and evaluate sources of existing data• Research sources of missing data• Assign data to tables and use field types and
sizes to define data
Succeeding in Business with Microsoft Access 2013 6
Discovering and Evaluating Sources of Existing Data
• Identify information that organization needs to manage and organize
• Might begin to see patterns that indicate how to organize data
• Database management system (DBMS)– Examples:• Oracle • Microsoft Access• MySQL
Succeeding in Business with Microsoft Access 2013
Discovering and Evaluating Sources of Existing Data (cont’d.)
• Data duplication– Undesirable • Additional space required in database to store
extra records• Leads to inconsistent and inaccurate data
• Data redundancy– Same data repeated for different records
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Succeeding in Business with Microsoft Access 2013
Identifying Sources of Missing Data
• Part of discovery phase• Must ask right questions of right people to get
right answers
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Succeeding in Business with Microsoft Access 2013 10
Assimilating the Available Information and Planning the Database
• First step in database design – Determine best way to organize data into logical groups of fields
• Entity– A person, place, thing, or idea
• Field – Single characteristic of entity– Also called column
• Record– Values in each field in table– Also called row
Succeeding in Business with Microsoft Access 2013 11
Assimilating the Available Information and Planning the Database (cont’d.)
• Table– Collection of fields that describe one entity– Also called relation
• Database– Collection of one or more tables
• Relational database– Contains related tables through fields that contain
identical data
Succeeding in Business with Microsoft Access 2013 12
Evaluating Field Values and Assigning Appropriate Data Types
• Data type – Determines how to store data in field– DBMSs use different names for some data types
• How do you determine which data type to assign each field? – Depends on what function you want to derive
from data– Each data type has different properties
Succeeding in Business with Microsoft Access 2013
Short Text and Long Text Data Types
• Short Text data type– Letters and numbers– Not used in calculations or formulas– Stores maximum of 255 characters– Default for all fields created in Access database
• Long Text data type– Store long passages of text– Can effectively store over 65,000 characters
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Succeeding in Business with Microsoft Access 2013
The Number Data Type
• Stores both positive and negative numbers • Contains up to 15 digits• Use for values used in calculations
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Succeeding in Business with Microsoft Access 2013
The Currency Data Type
• Includes two decimal places and displays values with dollar sign by default
• Use for monetary values
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Succeeding in Business with Microsoft Access 2013
The Date/Time Data Type
• Display values in format mm/dd/yyyy– Can also include time in different formats
• Used in calculations if necessary
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Succeeding in Business with Microsoft Access 2013
The AutoNumber Data Type
• Number automatically generated by Access • Produces unique values for each record• Useful to distinguish two records that share
identical information
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Succeeding in Business with Microsoft Access 2013
The Yes/No Data Type
• Assigned to fields requiring: – Yes/no– True/false– On/off
• Takes up one character of storage space• Make data entry easy– Check box
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Succeeding in Business with Microsoft Access 2013
The OLE Object Data Type
• Used to identify files created in another program – Then linked or embedded in database
• Abbreviation for Object Linking and Embedding
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Succeeding in Business with Microsoft Access 2013
The Hyperlink Data Type
• Assigned to fields that contain hyperlinks to: – Web pages– E-mail addresses– Files that open on: • Network• Workstation
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Succeeding in Business with Microsoft Access 2013
The Attachment Data Type
• Lets you store one or more files for each record in the database– Pictures– Documents– Charts– Spreadsheets
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Succeeding in Business with Microsoft Access 2013
The Calculated Type
• Uses data from fields in the same table to perform calculations
• When selected, opens Expression Builder so that you can create the calculation or expression
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Succeeding in Business with Microsoft Access 2013
The Lookup Data Type
• Creates fields to look up data in: – Another table– Or list of values created for field
• Makes data entry easy • Ensures that valid data entered into field
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Succeeding in Business with Microsoft Access 2013
Selecting the Correct Data Type
• Helps store correct data in correct format while using least amount of space
• Eases data entry and interactivity with data • Choosing certain data types results in user-
friendly interactive features– Drop-down menus – Check boxes– Hyperlinks
• Correctly manipulate data26
Succeeding in Business with Microsoft Access 2013
Assigning the Correct Field Size for Text Fields
• Important to consider field size when assigning data types– Minimize space reserved for each record by
assigning smallest data type that will store data• Be conservative when assigning field sizes– But not too conservative
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Succeeding in Business with Microsoft Access 2013
Assigning the Correct Field Size for Number Fields
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Table 1.3: Field Sizes for the Number data type
Succeeding in Business with Microsoft Access 2013
Dividing the Existing and Missing Data into Tables
• Tables – Single most important component of database– Most databases contain: • Multiple tables • Hundreds or even thousands of records
• Primary key – One field that creates unique value in each record – Used to identify each record in table– May be a combination of fields
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Succeeding in Business with Microsoft Access 2013
Naming Conventions
• Database tables must: – Have unique names– Follow established naming conventions
• General rules for naming objects– Object names cannot exceed 64 characters– Object names cannot include period, exclamation point,
accent grave, or brackets– Object names should not include spaces– Most developers capitalize first letter of each word
when table name includes two words
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Succeeding in Business with Microsoft Access 2013
Leszynski/Reddick Naming Conventions for Database Objects
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Succeeding in Business with Microsoft Access 2013
Level 1 Summary
• Discovery phase• Identify existing and missing data• Determine tables– Determine data types
• Follow naming conventions
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Succeeding in Business with Microsoft Access 2013
Level 2 Objectives:Understanding/Creating Table Relationships
• Understand relational database objects and concepts
• Create table relationships• Understand referential integrity
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Succeeding in Business with Microsoft Access 2013
Understanding Relational Database Objects
• Users can view data in tables by:– Opening table – Creating other objects
• Four main objects in database – Tables– Queries– Forms– Reports
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Succeeding in Business with Microsoft Access 2013
Tables
• Data in relational database stored in one or more tables
• View data in table – Open it and scroll through records
• Most of the time, three other main database objects used to display data
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Succeeding in Business with Microsoft Access 2013
Queries
• Query – Question asked about data stored in database
• Query results– Similar in look to a table– Fields displayed in columns – Records displayed in rows– This arrangement of data in Access is called a
datasheet
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Succeeding in Business with Microsoft Access 2013 38
Queries (cont’d.)
• Select query – Most commonly used query– Data selected from table on which query based
• Action query– Performs action on table– Select specific records in table and update them
Succeeding in Business with Microsoft Access 2013 39
Queries (cont’d.)
• Crosstab query – Performs calculations on values in field and
displays results in datasheet• SQL-specific query– Must be written in SQL code
Succeeding in Business with Microsoft Access 2013 40
Forms
• Used to view, add, delete, and update records– Based on table or query– Interface more attractive than table datasheet
• Customize form’s appearance with instructions and command buttons
• Navigation or Switchboard form– Form displayed when database is opened– Provides controlled method for users to open
objects in database
Succeeding in Business with Microsoft Access 2013
Reports
• Formatted presentation of data from table or query
• Created as printout or to be viewed on screen• Data displayed by report usually based on
query• Dynamic– Reflect latest data from object
• Cannot be used to modify data
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Succeeding in Business with Microsoft Access 2013
Other Database Objects
• SharePoint Services– Sharing data on company intranets and on the Web– Create a database on a SharePoint site to be
accessed by authorized individuals• Macro – Instructions to automate simple database tasks
• Module – Performs more sophisticated actions than macro– Written in Visual Basic for Applications (VBA)
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Succeeding in Business with Microsoft Access 2013
Understanding Relational Database Concepts
• Relational database– Contains multiple tables to store related
information• Common field – Field that appears in two or more tables and
contains identical data to relate tables– Primary key in first table– Foreign key in second table
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Succeeding in Business with Microsoft Access 2013
Creating Table Relationships
• Goal in good database design – Create separate tables for each entity– Ensure each table has primary key– Use common field to relate tables
• Relate two (or more) tables– Query them as though they are one big table
• Join – Specifies relationship between tables and properties
of relationship
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Succeeding in Business with Microsoft Access 2013
One-to-Many Relationships
• Abbreviated as 1:∞• One record in first table matches zero one or
many records in related table• Primary table– One “side”
• Related table– Many “side”
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Succeeding in Business with Microsoft Access 2013 48
One-to-Many Relationship Between Customers and Prescriptions
Succeeding in Business with Microsoft Access 2013
One-to-One Relationships
• Abbreviated as 1:1• Exists when each record in one table matches
exactly one record in related table
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Succeeding in Business with Microsoft Access 2013
One-to-One Relationship Between Physical and Billing Addresses
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Succeeding in Business with Microsoft Access 2013
Many-to-Many Relationships
• Abbreviated as ∞:∞• Each record in first table matches many
records in second table• Each record in second table matches many
records in first table• Junction table
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Succeeding in Business with Microsoft Access 2013
Many-to-Many Relationship Between Employees and Classes
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Succeeding in Business with Microsoft Access 2013 53
Understanding Referential Integrity
• Null value– Field does not contain any value
• Entity integrity– No duplicate records in table; each record is unique– No primary key field contains null values
• Referential integrity – If foreign key in one table matches primary key in
second table, values in foreign key must match values in primary key
Succeeding in Business with Microsoft Access 2013
Understanding Referential Integrity (cont’d.)
• When database does not enforce referential integrity – Problems occur that lead to inaccurate and
inconsistent data• Orphaned– No longer match between primary key in primary
table and foreign keys in related table
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Succeeding in Business with Microsoft Access 2013
Overriding Referential Integrity
• Might want to override referential integrity – Intentionally change primary key – Delete parent record
• Cascade Update Related Fields– Change primary key value so that DBMS
automatically updates appropriate foreign key values in related table
• Cascade Delete Related Records
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Succeeding in Business with Microsoft Access 2013
Level 2 Summary
• Main database objects– Table– Query– Form– Report
• Relationship types– One-to-many– One-to-one– Many-to-many
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Succeeding in Business with Microsoft Access 2013
Level 3 Objectives: Identifying and Eliminating Database Anomalies by Normalizing Data
• Learn the techniques for normalizing data• Evaluate fields that are used as keys• Test the database design
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Succeeding in Business with Microsoft Access 2013
Normalizing the Tables in the Database
• Normalization– Design process– Goals:• Reduce space required to store data by
eliminating duplicate data in database• Reduce inconsistent data in database by storing
data only once• Reduce chance of deletion update and insertion
anomalies
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Succeeding in Business with Microsoft Access 2013 61
Normalizing the Tables in the Database (cont’d.)
• Deletion anomaly – User unintentionally deletes only occurrence of
data in database• Update anomaly – User fails to update some records or updates
records erroneously, resulting in redundant data• Insertion anomaly – User cannot add data to database unless preceded
by entry of other data
Succeeding in Business with Microsoft Access 2013
Normalizing the Tables in the Database (cont’d.)
• Functional dependency– Column in table considered functionally dependent
on another column • If each value in second column associated with
exactly one value in first column• Partial dependency – Field dependent on only part of primary key
• Composite primary key– Primary key uses two or more fields to create
unique records in table62
Succeeding in Business with Microsoft Access 2013
Normalizing the Tables in the Database (cont’d.)
• Determinant– Field or collection of fields whose value
determines value in another field• Natural key– Primary key that details obvious and innate trait of
record• Artificial key– Field whose sole purpose is to create primary key
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Succeeding in Business with Microsoft Access 2013
First Normal Form (1NF)
• Repeating group– Field contains more than one value
• First normal form – Does not contain any repeating groups
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Succeeding in Business with Microsoft Access 2013
Second Normal Form (2NF)
• Table must be in 1NF • Must not contain any partial dependencies on
composite primary key• Tables in 1NF and contain primary key with
only one field – Automatically in 2NF
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Succeeding in Business with Microsoft Access 2013 66
Third Normal Form (3NF)
• Must be in 2NF and only determinants must be candidate keys– Candidate key • Field(s) that could function as primary key but was not
chosen to do so
• Tables in 3NF should not have transitive dependencies– Transitive dependency • Two nonkey fields both dependent on third field
Succeeding in Business with Microsoft Access 2013
Level 3 Summary
• Normal forms– First (1NF)– Second (2NF)– Third (3NF)
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Succeeding in Business with Microsoft Access 2013 68
Chapter Summary
• Discovery:– Identify existing and missing data– Organize data into tables– Determine data types for each field
• Tables, queries, forms, and reports• Table relationships– Established through common fields– Types• 1: ∞; 1:1; ∞ : ∞