1. Microsoft Access – Tutorial 3
Querying a Database
a query is a question you ask about data stored in a database
you tell Access what fields you need and what criteria Access should use to select the records ex. find records for employers located in a specific State or Province
queries allow you to:
display selected fields and records from a table
sort records
perform calculations
generate data for forms, reports and other queries
update data in the tables in a database
find and display data from two or more tables

2. Microsoft Access – Tutorial 3
Query by Example (QBE)
You Query by Example by giving Access an example of the information we are requesting
Access then retrieves the information we are requesting
We want to create a query to display:
employer ID
employer name
city
contact first name
contact last name
web site information
for each record in the Employer table

3. Microsoft Access – Tutorial 3
Query by Example (QBE)
open the Northeast database we created last week (I have included a copy in the Common Directory on the desktop)
Click Create > Query Design
show the Employer Table and the close the Show Table dialog box
maximize the Query window

4. Microsoft Access – Tutorial 3
Query by Example (QBE)
you will see the field list in a box entitled Employer (the table name)
you can double-click or drag fields to the design grid
in the design grid, you include the fields and record selection criteria for the information that you want to see
you can see the current results of your query at any time by View button or the Run button on the top left
the current results will appear in a datasheet view

5. Microsoft Access – Tutorial 3
Query by Example (QBE)
drag the split bar and resize the windows as you like
double-click the following fields in order: EmployerID, EmpoyerName, City, ContactFirstName, ContactLastName and Website
note the checkbox that that allows you to show or hide fields
click Run (or View (Datasheet View)) to see the results in a datasheet
click the View button to return to Design View
click the Save button on the toolbar and name the query EmployerAnalysis

6. Microsoft Access – Tutorial 3
Updating Data using a Query
return to the Datasheet view
indicate that The Adele Bannister House (10135) now has a website
change the Contact person for Alpine Touring Center (10152) to Mary Grant
close the Query and note that it has been added to the Queries in the Objects bar
open the Employers table and verify that the changes have been made
close the Employers table

7. Microsoft Access – Tutorial 3
Table Relationships
remember that Access is a relational database management system
relationships are created among tables by using common fields
this process is often called a join
when you join tables with a common field, you can extract data from them as if they were one table
the Employer and Position tables will be joined with the common field EmployerID (a foreign key)
you can use a query form or report to extract selected data from each table even though the information is in two tables

8. Microsoft Access – Tutorial 3
One-to-Many Relationships
a one-to-many relationship exists between two tables when one record in the first table matches zero, one or many records in the related table
and when one record in the in the second table matches exactly one record in the first table
the primary table is the one table in the one-to-many relationship
this is the Employer table
the related table is the many table
this is the Position table

9. Microsoft Access – Tutorial 3
One-to-Many Relationships
orphaned records can be created when inconsistencies occur between tables
for example:
if an Employer ID is changed in the Employer table
if an Employer is deleted from the Employer table
if a position is added for an Employer that doesn’t exist in the Employer table

10. Microsoft Access – Tutorial 3
One-to-Many Relationships
Referential Integrity is a set of rules that Access uses to prevent records from being orphaned
it maintains consistency between tables when you update data
when you add a record to a related table, a matching record must already exist in the primary table
if you attempt to change the value of a primary key in the primary table, Access prevents the change if matching records exist in a related table (however, if the cascade updates option is chosen, the foreing key values will be updated automatically)
Access prevents the deletion of records in a primary table if matching records exist in a related table (if cascade deletes option is selected all records with that key will be deleted – this is not recommended)

11. Microsoft Access – Tutorial 3
Defining Relationships
you can define relationships between tables using the Relationships window
Database Tools > Relationships
add Employer and Position and close the Show Table dialog box
lengthen and widen each window to show all fields
click and drag EmployerID from the Employer Table to EmployerID in the Position table
the Edit Relationships window will appear
the Primary Table, Related Table and Common Field will be visible

12. Microsoft Access – Tutorial 3
Defining Relationships
check Enforce Referential Integrity
note that the two Cascade options become available
check Cascade Update Related Fields (remember that it is not recommended to check the Cascade Delete Related Records as you may inadvertently delete records)
click create and note the join line that appears and the symbols on it
now create a one-to-many relationship between the NAICS table and Employer Table with NAICS code as the common field (foreign key)
click the Save button and Close the window

13. Microsoft Access – Tutorial 3
Multi-Table Queries
now that we have created Relationships among (joined) our tables, we can query them as one
create a new query in design view
add the Employer and Position tables
create a query in the following order:
EmployerName
City
StateProv
Openings
PositionTitle
StartDate
EndDate
run it and save the query as EmployerPositions

14. Microsoft Access – Tutorial 3
Sorting Data in a Query
sorting is rearranging records in a specified order or sequence
open the EmployerPositions query in datasheet view
select the first record in the Employer Name field and use the sort buttons (drop-down arrows on column heading) to sort alphabetically
to sort by more than one field go to Design View
select the entire column for Openings
click and drag it so that it is the last field (after EndDate)
use the Sort field to sort PositionTitle Ascending
sort Openings Descending
run the query
within groups of fields with the same Position Title, the record sorts the number of openings from highest to lowest
save the query

15. Microsoft Access – Tutorial 3
Filtering Data in a Query
you can filter query results using the Filter by Selection button
double-click the word clerk in one of the Position Title records
click the Filter by Selection button (located in Home > Sort and Filter group > selection)
you will see only results for different kinds of clerks
click the toggle filter button to turn off the filter
filter results for New Hampshire (NH)
Untoggle the filter and close the query

16. Microsoft Access – Tutorial 3
Defining Record Selection Criteria
you can specify a condition which is a criteria or rule that tells Access which records to display
we will Create > Query Wizard using a condition
click Simple Query Wizard and make sure the Table: Position is selected
add all the fields by clicking >>
remove both PositionID and EmployerID from the Selected Fields list box
to add fields from another table after the current set of fields, select Openings
now add EmployerName, StateProv, ContactFirstName, ContactLastName and Phone from the Employer Table

17. Microsoft Access – Tutorial 3
Defining Record Selection Criteria
click the Next button
make sure the Detail radio button is selected and click Next again
name the Query HousekeepingPositions and click the Modify the Query Design radio button and click Finish
in the PositionTitle Criteria type housekeeping
Access adds “ signs before and after the criteria
run and save the query
only housekeeping positions will be displayed

18. Microsoft Access – Tutorial 3
Formatting the Appearance of the sheet
select all the records
Home > Font Size (in the Font group)
change the size of the fonts to 8
double click between columns to resize them

19. Microsoft Access – Tutorial 3
Setting Range Criteria
open the HousekeepingPositions query in Design View
remove the PositionTitle criteria
set the Wage criteria >=17
run the query and Save (Office Button > Save As)
it As HighWageAmounts

20. Microsoft Access – Tutorial 3
Using Multiple Selection Criteria with the And operator
open the HousekeepingPositions query in Design View
add MA as criteria for StateProv
run the Query and you’ll see results that match both criteria
close and save the query
right click on the Query July1Positions in the Query window
rename it MAJuly1Positions

21. Microsoft Access – Tutorial 3
Using Multiple Selection Criteria with the Or operator
create a new query in Design view
use the Employer and Position tables and add the following fields: EmployerName, City, PositionTitle, HoursPerWeek, and Experience
set the HoursPerWeek criteria to <30
in order to select records in which either (not both) of the conditions is met type Yes in the or: field
run the query
sort it alphabetically ascending by Employer Name
Save it as HoursorExperience