Ch03 cmpt110

Succeeding in Business with Microsoft Access 2013

Analyzing Data For Effective Decision Making


Chapter Introduction

• Filter data in a Microsoft Office Access 2013 database– Retrieve and examine only the records you need– Sort data to rearrange records in a specified order

• Create complex queries• Explore advanced queries• Explore queries written in Structured Query

Language

2


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• Crosstab query• Filter by Form and Filter by Selection• Find duplicates query• Find unmatched records query

3


Tools Covered In This Chapter (cont’d.)

• Immediate IF (IIF) function• Parameter query• Design View• Select query• Simple Query Wizard• SQL commands• Top Values query• Wildcard character

4


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

5

Succeeding in Business with Microsoft Access 2013 6

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


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



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


Sorting Data to Increase Information Content

• Lets you view the information in a variety of ways• 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


Sorting Data To Increase Information Content (cont’d.)

• How Access sorts different types of data


Filtering Using the Filter Arrow


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


Using Queries to Answer Business Questions (cont’d.)

• Capabilities of Access queries:– 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


Using Queries to Answer Business Questions (cont’d.)

• Select query– Ask question based on one or more tables in

database– Result displayed in datasheet• Called recordset


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


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


Figure 3.7: Creating a summary query with the Simple Query Wizard


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



Creating Queries with Multiple Criteria

• Most queries involve more than one criterion• Represent AND criteria– Enter conditions in same criteria row in query

design grid• Specify OR criteria– Use “or” row of query design grid


Figure 3.10: Setting criteria for the query in Design view


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

23


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


Enhancing Query Criteria to Improve Data Analysis

• Expand criteria by using – Wildcards – Comparison operators


Using Wildcards for Inexact Query Matches

• Wildcard character– Placeholder – Stands for one or more characters

• Comment fields– Use same keywords throughout comments– Easily retrieve records later– Use wildcards when specifying keyword as a query

criterion • To select records that contain characters before and after

keyword



Using Wildcards for Inexact Query Matches (cont’d.)

• Access inserts – Word “LIKE” for criteria with wildcards quotation

marks around text• LIKE “*Spanish*”

– Pound signs around dates• #12/*/2013#


Using Comparison Operators to Refine Query Criteria

• Comparison operators– Compare value in field with range of values in

criterion• Clear the design grid to create or modify a

query– Start with same field list but blank grid



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


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

32



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

34


Level 2 Objectives:Creating More Complex Queries

• Design queries that compare data from more than one table

• Refine table relationships by specifying the join type

• Perform calculations in queries• Customize queries and their results



Using Queries to Find Duplicate Records

• Duplicates Query Wizard– Searches for duplicate values in fields– Improves business operations– Designed to identify records that contain same

information in particular field


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


Limiting the Records in the Query Results

• Limiting results to only a few records often aids analysis

• Top and Bottom Values– Set a sort order for the field– Descending to display the records with the highest

values– Ascending to display the records with the smallest

values

39



Using Parameter Values in Queries

• 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:]

41



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 ∞


Analyzing Data from More than One Table (cont’d.)

• 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


Analyzing Data from More than One Table (cont’d.)

• 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


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– Displays all records of one table

• Regardless of whether corresponding record is stored in related table


Figure 3.34: Inner join



Figure 3.36: Right outer join


Refining Relationships with Appropriate Join Types (cont’d.)

• Outer join types– Left– Right

• Use Join Properties dialog box– To change join type– By default, tables are related using inner joins– Options for outer joins


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



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• Perform numeric date and text computations on each record • Using data from one or more fields

53


Calculating Statistical Information

• Aggregate functions– Mathematic and statistical operations – Apply to records that meet query’s selection

criteria

54



Figure 3.43: Using aggregate functions in a query


Creating Calculated Fields in a Query

• Expression – Arithmetic formula for calculation– Use standard arithmetic operators– Use parenthesis for complex expressions

• Calculated field– Add to query design grid– Type expression

• Expression Builder– Build complex expressions

57


Creating Calculated Fields in a Query (cont’d.)

• Function– Performs standard calculation– Returns value

• Date()– Provides today’s date

• Field properties– Change format and number of decimal places for

calculated field



Concatenating in Queries

• Concatenation– Combining contents of two or more fields– Operator• &

– Example• Name [EmpFirst]& " " & [EmpLast]

60


Level 2 Summary

• Use queries to select from more than one table• Join types– Inner– Right outer– Left outer

• Calculated field types– Predefined– Custom

61


Level 3 Objectives: Exploring Advanced Queries and Queries Written in Structured

Query Language

• Calculate and restructure data to improve analysis

• Examine and create advanced types of queries• Make decisions in a query using the

immediate IF (IIF) function• Develop queries using SQL

62


Analyzing Query Calculations

• More advanced queries– Crosstab query• Most useful for preparing data for further analysis

– Action queries• Change or move many records in one operation

– Four types of action queries:• Append, update, delete, and make-table


Analyzing Query Calculations (cont’d.)

• Crosstab queries – Special type of totals query – Perform 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


Creating a Crosstab Query

• To create:– Use Design View• Start with select query that includes numeric values or

summary calculations– Use the Crosstab Query Wizard• Guides you through the steps• Shows samples of how the crosstab results will look

65



Modifying 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

67




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

70


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– Can bring data from another source into database


Removing Records from Tables with Delete Queries

• Delete query – Removes information from table – Based on specified criteria– All records meeting criteria permanently removed

• Create select query first– Convert to delete query

• Cascading deletes

72


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

73


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)


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/manage relational databases

• Create query in Design View– Access translates entries and criteria into SQL

statements


Customizing Queries Using Structured Query Language (cont’d.)

• 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


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



Creating a Union Query Using SQL

• Union query– Combine, or unite, the results from two or more

select queries


Level 3 Summary

• Crosstab and Action queries• IFF function• SQL– Use SQL view to edit SQL directly

80


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

81

Art & Photos

Ch03 cmpt110