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Chapter 3
Analyzing Data For Effective Decision
Making
Chapter Introduction
• Organize and Retrieve information from an
Access 2010 database
• Create complex queries
• Explore advanced queries
• Explore queries written in Structured Query
Language
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Tools Covered In This Chapter
• Action queries (update, append, delete,
crosstab, and make-table)
• Aggregate functions (Avg, Max, Min, Sum)
• Calculated field
• Comparison and logical operators
• Filter by Form and Filter by Selection
• Find duplicates query
• Find unmatched records query
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Tools Covered In This Chapter
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Immediate IF (IIF) function
Parameter query
Select query
Simple Query Wizard
SQL commands
Top Values query
Wildcard characters
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Level 1 Objectives: Organizing and Retrieving
Information from a Database
• Filter and sort data to make it more
meaningful
• Create simple queries to answer business
questions
• Develop queries using comparison criteria and
wildcards
• Verify and print query results
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Filtering and Sorting Data
• Filter
– Restricts data in single table to create temporary
subset of records
– See only certain records in table based on
specified criteria
• Sorting records
– Organizing in particular order or sequence
– Sort records regardless of whether table filtered
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Filtering by Selection
• Tools
– Filter by Selection
• Select particular field in datasheet
• Display only data that matches contents of field
• Specify only one criterion for filter
– Filter by Form
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Using Filter by Selection to Display a Temporary
Subset of Records
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Filtering by Form
• Specify two or more criteria
• Filter for comparative data
– Use comparison operators
• AND criteria
– Selects records that contain all specified values
• OR criteria
– Selects records that contain any of specified
values
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Sorting Data to Increase Information Content
• Organizes data and increases information value
• Access sorts records based on primary key values
– Use sorting to change order
• To sort
– Select sort field
• Sort on multiple fields
– Move fields in datasheet view so that they are
adjacent
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Sorting Data To Increase Information Content
• Primary sort field
– Access sorts records by this field first
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Filtering Using the Filter Arrow
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Using Queries to Answer
Business Questions
• Query
– Database object
– Stores criteria for selecting records from one or
more tables based
– Save query
• Use it again
– More powerful than filter
• Display only some fields in table
• Create fields that perform calculations
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Using Queries to Answer
Business Questions (continued)
• Capabilities of Access queries:
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Display selected fields and records from table
Sort records on one or multiple fields
Perform calculations
Generate data for forms reports and other queries
Update data in database
Find and display data from two or more tables
Create new tables
Delete records in table based on one or more criteria
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Using Queries to Answer
Business Questions (continued)
• Select query
– Ask question based on one or more tables in
database
– Result displayed in datasheet
• Called recordset
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Using the Simple Query Wizard
to Create a Query
• Simple query wizard
– Presents list of tables and queries in database
• And fields that they contain
– Select fields from one or more tables
– Wizard creates and displays results
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Including Summary Statistics in a Query for
Data Analysis
• Summary query
– Groups records
– Calculate sum, average, minimum, or maximum
value in each selected field
– Count records in table or query
• Click summary options button
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Creating a Query in Design View
• Select query window in Design view has two
sections
– Area for field lists at top of window
– Design grid below it
• Add tables for query to top part of window
– Appear as field lists
• Query by example (QBE)
– Typing search value as a criterion
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Query Design View Tools
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Creating Queries with
Multiple Criteria
• Most queries involve more than one criterion
• Represent AND criteria
– Entering conditions in same criteria row in query
design grid
• Specify OR criteria
– Use “or” row of query design grid
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Setting Criteria for the
Query in Design View
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Specifying Sort Order in Queries
• Query results appear in same order as data
from underlying tables
– Unless specify sort order when designing query
• Sort order determined from left to right
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Running a Query
• Click Run button in the Results group
– Access displays datasheet of records
• Save query
– Save only design
– Not values from tables displayed in results
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Enhancing Query Criteria to Improve Data
Analysis
• Expand criteria by using
– Wildcards
– Comparison operators
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Using Wildcards for Inexact
Query Matches
• Wildcard character
– Placeholder
– Stands for one or more characters
• Comment fields
– Use same keywords throughout memos
– Easily retrieve records later
– Use wildcards when specifying keyword as a query
criterion
• To select records that contain characters before and after
keyword
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Wildcard Characters Used
in Queries
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Using Wildcards for Inexact Query Matches
(continued)
• Access inserts
– Word “LIKE” for criteria with wildcards quotation
marks around text
• LIKE “*Spanish*”
– Pound signs around dates
• #12/*/2013#
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Using Comparison Operators to Refine Query
Criteria
• Comparison operators
– Compare value in field with range of values in
criterion
• Clear the grid
– Start with same field list but blank grid
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Comparison Operators
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Verifying and Printing
Query Results
• Verify query results before
– Distributing query to others
– Using it as basis for decisions
• Use business knowledge
– Determine whether results adequately answer
question
• Print query datasheet
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Modifying Query Datasheets
• Improve appearance of query or table
datasheet
• Resize column widths in any datasheet
– Double-click line between field names to resize
columns to best fit
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Formatting Options for
Query and Table Datasheets
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Level 1 Summary
• Use filtering and sorting to change data
display
• Develop queries using
– Simple query wizard
– Design view
• Use comparison operators and wildcards to
make queries more flexible
• Verify query results using business knowledge
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Level 2 Objectives:
Creating More Complex Queries
• Design special types of queries
• Design queries that compare data from more
than one table
• Refine table relationships by specifying the
join type
• Perform calculations in queries
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Designing Special Types of Queries
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Using Queries to Find Duplicate Records
• Duplicates Query Wizard
– Searches for duplicate values in fields
– Improve business operations
– Designed to identify records that contain same
information in particular field
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Using Queries to Find Unmatched Records
• Find Unmatched Query Wizard
– Compares records in two specified tables or
recordsets
– Finds all records in one table or query that have
no related records in second table or query
– Requires that two tables being compared have
common field
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Limiting the Records in the Query Results
• Limiting results to only a few records often
aids analysis
• Top and Bottom Values
– Sorts and then filters records
– Display specified number of records that contain
top or bottom values
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Top Values Query Design and Results
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Designing a Parameter Query
• Parameter values
– Phrase usually in form of a question or instruction
– Enclosed in square brackets
– Serves as prompt to user to enter value
– Example
• [Enter a job ID:]
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Parameter Query to Allow User Input when the
Query Is Run
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Analyzing Data from More than One Table
• Data from more than one table required to
answer question
– Combine records from two or more tables
– Display only information needed
• Work in design view to specify criteria for
selecting records from multiple tables
• Lines between tables link primary key to foreign
key field
– Primary key designated with 1
– Foreign key designated with ∞
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Analyzing Data from More than One Table
(continued)
• Join tables
– Linking of tables using primary and foreign keys
– Established relationship
– Or
• Each table shares field with same or compatible data type
• One join field primary key
• If tables do not include fields that can be joined
– Add one or more extra tables or queries
– Link tables that contain the data
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Analyzing Data from More than One Table
(continued)
• Use queries as source of underlying data for
another query in place of one or more tables
• Create queries based on more than one object
– Should not use any table or query that does not
have common field with at least one of the other
tables or queries
– Otherwise Access displays every combination of
records between two tables
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Refining Relationships with Appropriate Join
Types
• Inner join
– Displays all records in one table that have
corresponding values in common field in another
table
– Records must match before being displayed in
query results
• Outer join
– Display all records of one table
– Regardless of whether corresponding record
stored in related table
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Refining Relationships with Appropriate Join
Types (continued)
• Outer join types
– Left
– Right
• Use join properties dialog box
– To change join type
– By default tables related using inner joins
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Using Logical Operators
to Specify Multiple Conditions
• Logical operators
– Test values that can only be true or false
• Place conditions in separate fields in same
criteria row of design grid
– All conditions in row must be met to select record
• NOT logical operator
– Excludes values that don’t meet criterion
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Logical Operators
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Performing Calculations with Queries
• Any information derived from fields in table or
query should be calculated in query
– Rather than included as data in table
• Calculation types
– Predefined
• Compute amounts for groups of records or for all records
combined in query
– Custom
• Performs numeric date and text computations on each
record
• Using data from one or more fields
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Calculating Statistical Information
• Aggregate functions
– Arithmetic and statistical operations
– Apply to records that meet query’s selection
criteria
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Using Aggregate Functions in a Query
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Creating Calculated Fields in a Query
• Expression
– Arithmetic formula used to make calculation
– Use standard arithmetic operators
– Use parenthesis for complex expressions
• Calculated field
– Add to query design grid
– Type expression
• Expression builder
– Build complex expressions
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Creating Calculated Fields in a Query
(continued)
• Function
– Perform standard calculation
– Return value
• Date()
– Provides today’s date
• Field properties
– Change format and number of decimal places for
calculated field
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Field Properties
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Concatenating in Queries
• Concatenation
– Combining contents of two or more fields
– Operator
•&
– Example
• Name [EmpFirst]& " " & [EmpLast]
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Level 2 Summary
• Use queries to select data from more than one
table
• Join types
– Inner
– Right outer
– Left outer
• Calculated field types
– Predefined
– Custom
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Level 3 Objectives: Exploring Advanced Queries
and Queries Written in Structured Query Language
• Modify data using queries
• Calculate and restructure data to improve
analysis
• Make decisions in a query using the
immediate IF (IIF) function
• Develop queries using SQL
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Modifying Data Using Queries
• Crosstab queries
– Special type of totals query
– Performs aggregate function calculations on
values of one database field
– Determine exactly how summary data appears in
results
– Calculate and restructure data
• Analyze it more easily
– Work especially well with time-series data
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Creating a Crosstab Query
• To create use
– Use a wizard
• Often need to create query first
– Or design view
• Start with select query that includes numeric values or
summary calculations
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Crosstab Field Settings
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Calculating and Restructuring Data Using
Queries
• Action queries
– Modify data in table
– Add records to or delete records from table
– Create new table
• Backup data before using action query
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Access Action Queries
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Process for Archiving Data
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Archiving Data with Make-table Queries
• Make-table query
– Creates table from some or all of the fields and
records in existing table or query
– Access does not delete selected fields and records
from existing table
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Adding Records to Tables with Append Queries
• Append query
– Select records from one or more tables by setting
criteria
– Add those records to end of another table
– Selected records also remain in original tables
– Table to which records added must already exist
– Also use to bring data from another source into
database
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Removing Records from Tables with Delete
Queries
• Delete query
– Removes information from table
– Based on specified criteria
– All records meeting criteria permanently removed
from table
• Create select query first
– Convert to delete query
• Cascading deletes
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Updating Data with an Update Query
• Update query
– Changes values of data in one or more existing
tables
– Create select query first
• Change type to update query
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Making Decisions in Queries
• IF statement
– Tests condition
– Takes one action if condition true
– Takes another action if condition false
• IIF function
– Make if decision
– Format
• IIF(condition to test, what to do if true, what to do if
false)
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Customizing Queries Using Structured Query
Language
• Access designed as database management system
(DBMS) for
– Small businesses
– Or departments within large businesses
• Structured query language
– Common query language of most DBMSs
– Use to query, update, and manage relational databases
• Create query in design view
– Access translates entries and criteria into SQL statements
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Customizing Queries Using Structured Query
Language (continued)
• View statements by switching from Design
view to SQL view
• SELECT statement defines
– What data query should retrieve from database
– How it should present data
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Exploring the Components
of an SQL Query
• Keywords
– Use to construct SQL statements
• Most developers place each statement on
separate line
– To make SQL code easy to read
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Common SQL Keywords
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Level 3 Summary
• Action queries
– Make new tables
– Append data
– Delete data
– Update data
• IFF function
• SQL
– Use SQL view to edit SQL directly
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Chapter Summary
• Queries retrieve data from one or more tables
– Action queries update data
– Perform calculations
– Make decisions using IIF function
• SQL
– Used to interact with relational databases
– Use SQL view to view/edit SQL statements
generated by Access
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