© Paradigm Publishing, Inc. 1. 2 Access 2010 Level 2 Unit 1Advanced Tables, Relationships, Queries,...

Contents© Paradigm Publishing, Inc. 1


Access 2010

Level 2

Unit 1 Advanced Tables, Relationships,Queries, and Forms

Chapter 2 Building Relationships andLookup Fields


Building Relationships and Lookup Fields

Build Relationships Define a Multiple-Field Primary Key CHECKPOINT 1 Create a Field to Look Up Values in Another Table Create a Field That Allows Multiple Values Create Indexes Normalize the Database CHECKPOINT 2

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Build Relationships

A relationship is based upon an association between two tables.

When building relationships, consider associations between tables and how the associations affect data that will be entered into the tables.

Access provides for three types of relationships: one-to-many, one-to-one, and many-to-many. In Access Level 1, Chapter 2, you learned about one-to-many and one-to-one relationships.


Build Relationships…continued

One-to-many relationships are the most common type of relationship created in Access.

A foreign key is a field included in a table to create a relationship to a field that is a primary key in another table.



A diamond symbol represents a relationship.

The Customers-to-WorkOrders one-to-many relationship can be illustrated using a diagram similar to the one shown below.



To create a one-to-many relationship:1. Click the Database Tools

tab.2. Click the Relationships

button in the Relationships group.

3. At the Show Table dialog box, add the desired tables.

4. Close the Show Table dialog box.

Show Table dialog box



5. Drag the primary key field name from the primary table to the foreign key field name in the related table.

6. At the Edit Relationships dialog box, click the Create button.

Edit Relationships dialog box



one-to-many relationship

The Technicians to WorkOrders relationship diagram is shown below.



To edit a relationship:1. Click the Database Tools

tab.2. Click the Relationships

button in the Relationships group.

3. Click the black join line between the tables.

4. Click the Edit Relationships button.

5. At the Edit Relationships dialog box, select the desired options.

6. Click OK.

Edit Relationships dialog box



referential integrity turned on

With referential integrity turned on, the number 1 and the infinity symbol (∞) display on the join lines, as shown below.



The Customers to ServiceContracts relationship diagram is shown below.

one-to-one relationship


Build Relationships…continuedTo create a one-to-one relationship:1. Click the Database Tools tab.2. Click the Relationships button in

the Relationships group.3. At the Show Table dialog box, add

the desired tables. 4. Close the Show Table dialog box.5. Drag the primary key field name

from the primary table to the primary key field name in the related table.

6. At the Edit Relationships dialog box, select the desired relationship options.

7. Click the Create button.

One-To-One Relationship Type



The many-to-many relationship between the Customers and Technicians tables is depicted below.

many-to-many relationship



A many-to-many relationship is problematic because the nature of the relationship creates duplicate records.

To resolve the duplication and create unique entries, a third table is used to associate or link the many-to-many tables. The third table is called a junction table.



The WorkOrders junction table contains two foreign keys—the primary key from each table in the many-to-many relationship.

In the diagram below, the WorkOrders table is the junction table.


Define a Multiple-Field Primary Key

Profiles Table

Some customers may have more than one computer in their home or office and, in turn, each computer may contain many different usernames.

In this table, you will define all three fields as a primary key. A primary key that is made up of two or more fields is called a composite key.


Define a Multiple-Field Primary Key…continued

To create a multiple-field primary key:1. Open the table in Design

view.2. Select the first field.3. Hold down the Shift key (for

an adjacent row) or the Ctrl key (for a nonadjacent row) and select the second field.

4. Click the Primary Key button in the Tools group in the Table Tools Design tab.

5. Save the table.

key icon


CHECKPOINT 11) Access provides for how many

types of relationships?a. 1b. 2c. 3d. 4

3) The Relationships button is located in this tab.a. Homeb. Createc. External Datad. Database Tools

2) These relationships are the most common type of relationship created in Access.a. one-to-noneb. none-to-onec. one-to-oned. none-to-none

4) This table is a table that contains at least two foreign keys.a. junctionb. functionc. truncationd. situation

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Create a Field to Look Up Values in Another Table In Level 1, Chapter 4, you learned how to create a

lookup list by typing the values that you wanted to appear in the list as you worked through the steps of the Lookup Wizard.

You can also create a lookup field in which the drop-down list is populated with the values found in records from another table.

With a lookup field, the user enters data by pointing and clicking rather than by typing an entry in the field.


Create a Field to Look Up Values in Another Table…continued

To create a lookup field to another table:1. Open the table in Design

view.2. Click in the Data Type

column of the lookup field.3. Click the down-pointing

arrow.4. Click the Lookup Wizard

option.5. At the first Lookup Wizard

dialog box, click Next.continues on next slide…

first Lookup Wizard dialog box



6. At the second Lookup Wizard dialog box, choose the table.

7. Click Next.continues on next slide…

second Lookup Wizard dialog box



8. At the third Lookup Wizard dialog box, choose the fields to display in the column.


third Lookup Wizard dialog box



10. At the fourth Lookup Wizard dialog box, choose the field by which to sort.


fourth Lookup Wizard dialog box



12. At the fifth Lookup Wizard dialog box, expand the column widths if necessary.

13. Clear the Hide key column if desired.14. Click Next.continues on next slide…

fifth Lookup Wizard dialog box



15. At the sixth Lookup Wizard dialog box, choose the field value to store in the table.

16. Click Next.17. Click Finish.18. Click Yes.

sixth Lookup Wizard dialog box


Create a Field That Allows Multiple Values

TechSkills Table

For each technician in the table below, you would open a list in the Certifications field and click the check box next to the applicable certification title.

In the OperatingSys field, another list could be created to keep track of the operating systems for which the technician is considered an expert.


Create a Field That Allows Multiple Values…continued

To create a multiple-value lookup list:1. Open the table in Design

view.2. Start the Lookup Wizard

for the desired field.3. Create the list by typing

values or binding data to a field in another table.

4. At the last Lookup Wizard dialog box, click the Allow Multiple Values option.

5. Click Finish.6. Click Yes.

Allow Multiple Values option


Create Indexes

An index is a list created by Access that contains pointers to direct Access to the location of a record in a table.

A database index is very similar to an index you would find at the back of a textbook. You search an index for a keyword that is associated with the topic you want to find and the index directs you to the appropriate page number(s) in the book.


Create Indexes…continued

You can create an index that restricts data in a field to unique values.

This creates a field similar to a primary key in that Access will not allow two fields to hold the same data.



To create a single-field index:1. Open the table in Design view.2. Make the desired field active.3. Click in the Indexed property box.4. Click the down-pointing arrow.5. Click Yes (Duplicates OK) or Yes (No Duplicates).6. Save the table.

Indexed property box



To create a multiple-field index:1. Open the table in Design view.2. Click the Indexes button in the

Show/Hide group in the Table Tools Design tab.

3. Click in the first blank row in the Index Name column.

4. Type a name for the index.5. Press Tab.6. Click the down-pointing arrow in

the Field Name column.7. Click the desired field.8. If necessary, change the sort

order.continues on next slide…

Field Name column



9. Click in the Field Name column in the next row.

10. Click the down-pointing arrow.

11. Click the desired field.12. If necessary, change the

sort order.13. Continue repeating

Steps 9-12 until finished.

14. Close the Indexes window.

sort order


Normalize the Database

Normalizing a database involves reviewing the database structure and ensuring the tables are set up to eliminate redundancy.

Three normalization states are tested: first normal form, second normal form, and third normal form.


Normalize the Database…continued

A table meets first normal form when the table does not contain any fields that could be broken down into smaller units and when the table does not have similar information stored in several fields.



Second normal form only concerns tables that have a multiple-field primary key, also known as a composite key.

A table with a composite key meets second normal form when the table is in first normal form and when all of the fields in the table are dependent on all of the fields that form the primary key.



Third normal form applies to a table that has a single primary key and is in first normal form.

If a field exists in the table for which the field value is not dependent on the field value of the primary key, the table is not in third normal form.


CHECKPOINT 21) To assist with creating lookup

fields, Access provides this.a. Table Guideb. Table Wizardc. Lookup Guided. Lookup Wizard

3) Use this type of index if you sort or search a large table by two or more fields at the same time.a. single-fieldb. multi-fieldc. duplex-fieldd. duplicate-field

2) This is a list created by Access containing pointers.a. Indexb. Stampc. Certificated. Table

4) How many normalization states are tested?a. 1b. 2c. 3d. 4

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Building Relationships and Lookup Fields

Create and edit relationships between tables including one-to-many, one-to-one, and many-to-many relationships

Define a table with a multiple-field primary key Create and modify a lookup field to populate records with

data from another table Create a lookup field that allows multiple values in records Create single-field and multiple-field indexes Define what is meant by normalization Determine if a table is in first, second, and third normal

form

Summary of Presentation Concepts

© Paradigm Publishing, Inc. 1. 2 Access 2010 Level 2 Unit 1Advanced Tables, Relationships, Queries,...

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Transcript of © Paradigm Publishing, Inc. 1. 2 Access 2010 Level 2 Unit 1Advanced Tables, Relationships, Queries,...