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Ch01 Access
 

Ch01 Access

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    Ch01 Access Ch01 Access Presentation Transcript

    • Preparing to Automate Data Management
      1
      Chapter 1
      “You can use all the quantitative data you can get, but you stillhave to distrust it and use your own intelligence and judgment.” — Alvin Toffler
    • Chapter Introduction
      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 Office Access 2007: A Problem-Solving Approach
      2
    • Database Design Process: The Discovery Phase
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      3
    • Level 1 Objectives: Examining Existing and Missing Sources of Data
      Discover and evaluate sources of existing business data
      Research sources of missing or incomplete data
      Assign data to tables and use field types and sizes to define data
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      4
    • 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)
      Includes:
      Oracle
      ColdFusion
      Microsoft Access
      MySQL
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      5
    • 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
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      6
    • Researching Sources of Missing Data
      Part of discovery phase
      Must ask right questions of right people to get right answers
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      7
    • Assimilating the Available Information and Planning the Database
      First step in database design
      Determine best way to organize data into logical groups of fields
      Field
      Single characteristic of entity
      Also called column
      Record
      Values in each field in table
      Also called row
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      8
    • Assimilating the Available Information and Planning the Database (continued)
      Table
      Collection of fields that describe one entity
      Also called entity or relation
      Database
      Collection of one or more tables
      Relational database
      Contains related tables through fields that contain identical data
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      9
    • 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 Office Access 2007: A Problem-Solving Approach
      10
    • Common Data Types and Their Descriptions
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      11
    • The Text and Memo Data Types
      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
      Memo data type
      Store long passages of text
      Displays only 64,000 characters
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      12
    • The Number Data Type
      Stores both positive and negative numbers
      Contains up to 15 digits
      Use for values used in calculations
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      13
    • The Currency Data Type
      Includes two decimal places and displays values with dollar sign
      Use for monetary values
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      14
    • The Date/Time Data Type
      Display values in format mm/dd/yyyy
      Can also include time in different formats
      Used in calculations if necessary
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      15
    • The AutoNumber Data Type
      Unique to Access
      Number automatically generated by access
      Produces unique values for each record
      Useful to distinguish two records that share identical information
      Produces values of up to nine digits
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      16
    • 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
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      17
    • 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
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      18
    • The Hyperlink Data Type
      Assigned to fields that contain hyperlinks to
      Web pages
      E-mail addresses
      Files that open in
      Web browser
      E-mail client
      Another application
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      19
    • The Lookup Wizard 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
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      20
    • The Attachment Data Type
      New to Access 2007
      Lets you store one or more files for each record in the database
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      21
    • 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 data
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      22
    • 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
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      23
    • Assigning the Correct Field Size for Number Fields
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      24
    • 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
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      25
    • Database Design Process: Planning the Tables
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      26
    • 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
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      27
    • Leszynski/Reddick Naming Conventions for Database Objects
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      28
    • Level 1 Summary
      Discovery phase
      Identify existing and missing data
      Determine tables
      Determine data types
      Follow naming conventions
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      29
    • Level 2 Objectives:Understanding and Creating Table Relationships
      Understand relational database objects and concepts
      Create table relationships
      Understand referential integrity
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      30
    • 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
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      31
    • 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 normally
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      32
    • Queries
      Query
      Question asked about data stored in database
      Query results
      Look similar to table
      Fields displayed in columns
      Records displayed in rows
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      33
    • Queries (continued)
      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
      Crosstab query
      Performs calculations on values in field and displays results in datasheet
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      34
    • Forms
      Used to view add delete, update and print records in database
      Based on table or query
      Interface more attractive than table datasheet
      Customize form’s appearance with instructions and command buttons
      Switchboard
      Form displayed when database opened
      Provides controlled method for users to open objects in database
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      35
    • Form Based on a Table
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      36
    • 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
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      37
    • Accounts Receivable Report
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      38
    • Other Database Objects
      Macro
      Set of instructions
      Automate certain database tasks
      Usually automates simple tasks
      Module
      Contains instructions to automate database task
      Written in Visual Basic for Applications (VBA)
      Performs more sophisticated actions than macro
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      39
    • Understanding Relational Database Concepts
      Flat file database
      Simple database
      Contains single table of information
      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
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      40
    • Creating Table Relationships
      Take advantage of interrelated objects
      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
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      41
    • One-to-Many Relationships
      Abbreviated as 1:M
      One record in first table matches zero one or many records in related table
      Primary table
      One side
      Related table
      Many side
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      42
    • One-to-Many Relationship Between Customers and Prescriptions
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      43
    • One-to-One Relationships
      Abbreviated as 1:1
      Exists when each record in one table matches exactly one record in related table
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      44
    • One-to-One Relationship Between Physical and Billing Addresses
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      45
    • Many-to-Many Relationships
      Abbreviated as M:N
      Each record in first table matches many records in second table
      Each record in second table matches many records in first table
      Junction table
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      46
    • Many-to-Many Relationship Between Employees and Classes
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      47
    • Understanding Referential Integrity
      Null value
      Field does not contain any value
      Entity integrity
      Guarantee that there are no duplicate records in table
      Each record 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 Office Access 2007: A Problem-Solving Approach
      48
    • Understanding Referential Integrity (continued)
      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
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      49
    • Referential Integrity Errors
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      50
    • Overriding Referential Integrity
      Might want to override referential integrity
      Intentionally change primary key
      Delete parent record
      Cascade updates
      Change primary key value so that DBMS automatically updates appropriate foreign key values in related table
      Cascade deletes
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      51
    • Level 2 Summary
      Main database objects:
      Table
      Query
      Form
      Report
      Relationship types:
      One-to-many
      One-to-one
      Many-to-many
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      52
    • 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
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      53
    • Normalizing the Tables in the Database
      Normalization
      Design process
      Goals
      Reduces space required to store data by eliminating duplicate data in database
      Reduces inconsistent data in database by storing data only once
      Reduces chance of deletion update and insertion anomalies
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      54
    • Normalizing the Tables in the Database (continued)
      Deletion anomaly
      User deletes data from database
      Unintentionally deletes only occurrence of data in database
      Update anomaly
      Due to redundant data in database
      User fails to update some records or updates records erroneously
      Insertion anomaly
      User cannot add data to database unless preceded by entry of other data
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      55
    • Normalizing the Tables in the Database (continued)
      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 table
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      56
    • Normalizing the Tables in the Database (continued)
      Determinant
      Field or collection of fields whose value determines value in another field
      Inverse of dependency
      Natural key
      Primary key that details obvious and innate trait of record
      Artificial key
      Field whose sole purpose is to create primary key
      Usually visible to users
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      57
    • Normalizing the Tables in the Database (continued)
      Surrogate key
      Computer-generated primary key
      Usually invisible to users
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      58
    • First Normal Form
      Repeating group
      Field contains more than one value
      First normal form
      1NF
      Does not contain any repeating groups
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      59
    • 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
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      60
    • Third Normal Form
      3NF
      Only determinants must be candidate keys
      Candidate key
      Field or collection of fields that could function as primary key but was not chosen to do so
      Transitive dependency
      Occurs between two nonkey fields both dependent on third field
      Tables in 3NF should not have transitive dependencies
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      61
    • Level 3 Summary
      Normal forms
      First (1NF)
      Second (2NF)
      Third (3NF)
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      62
    • Chapter Summary
      Discovery:
      Identify existing and missing data
      Organize data into tables
      Determine data types for each field
      Table relationships
      Established through common fields
      Types
      1:M
      1:1
      M:N
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      63
    • Chapter Summary (continued)
      Normalization
      Reduces duplication and inconsistency
      Forms:
      1NF
      2NF
      3NF
      Succeeding in Business with Microsoft Office Access 2007: A Problem-Solving Approach
      64