Exploring Microsoft Access
Chapter 5
One-to-Many Relationships:
• One-to-many relationship essential in
database design
• Use the Relationships window
• Define referential integrity
• Distinguish between a main form and a subform
• Create a query based on multiple tables
• Create a main form with two subforms
Overview
(1 of 2)• The real power of Access: one-to-many relationships between tables
• Primary key of one table is foreign key of the related table
• Main forms and subforms created from related tables.
• Reports based on a multiple-table query
Relationships Window
CustomerID is primary key
in Customers table Relationship line
CustomerID is foreign key in Loans table Enforce Referential
Referential Integrity
(1 of 2)• Access automatically implements a form of data validation during data entry
• Can enter a record in the “one” table, but not in the “many” table if record contains an invalid value for the foreign key
Referential Integrity
(2 of 2)Delete Record button
Click + to display related records (subdatasheet)
Subforms
• Subform is a form within a form
• Main form would be based on primary table, while subform is based on related table
• Use Subform Wizard
Form Wizard
(1 of 4)Select the table or query for
the form
Select all fields to add to the form
Step 1
Form Wizard
(2 of 4)Step 3
Select the table or query for
the subform
Select all fields
Form Wizard
(3 of 4)Step 4
Step 5 Choose how to display
Form Wizard
(4 of 4)Subform
Customer C01
Loans for
Customer C01
Status bar for
Multiple Table Queries
• Query information from two tables
• Create a select query using both tables
Multiple Table Queries
Column selector
Multiple Subforms
(1 of 2)• A main table can have multiple levels of subforms
Multiple Subforms
(2 of 2)Customer C01
Chapter 5 Summary
(1 of 2)• Access database may contain multiple tables
• Each table has a primary key which is the foreign key of a related table
• Relationships window to create one-to-many relationships
Chapter 5 Summary
(2 of 2)• Subform is a form within a form
• A main form can have multiple subforms
• Select query can include fields from several tables
