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05 – Database Design: Sub-forms

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Session Aims & Objectives• Aims

– To allow easier data entry from multiple tables using forms

• Objectives,by end of this week’s sessions, you should be able to:

– create a sub form that allows data entry into a related table

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What is a Main and Subform?• In a One to Many relationship:

– Main form displays the ‘One’ record• Master table (or Query)

– Subform displays the ‘Many’ records• Child or Details table (or Query)

• Customer Order Details– Main contains Customers, Customer Orders and Order tables

– Subform contains Order Lines and Products tables

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Sub-forms: Why?• Usually used for tables with a One-to-Many

relationship• Need to enter several records in one table link to

one in another• Wish to view all records from one table which are

related to one in another

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Sub-forms: Why?• Creation of coherent

data– Ensures orders are

‘linked’ to the correct customer

• View data linked to a record– Check current orders– Check back orders

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How do they work?• Main form produced from a table or query

– Displays data from the ‘one’ side of relationship

• Subform produced from different table or query– Displays data from the ‘many’ side of relationship

• Subform inserted into Main form– Subform only displays records linked to Main– All data available form that one-to-many

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Creating Main and Subforms…

• Create query for Main form

• Create query for Subform(s)

• Create form layouts:– Main– Subform(s)

• Insert Subform(s) into Main form

• Link Forms• Final format to create

desired view

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An Example…• ACME Customer

Order Details

• Select Customer– View items to send– Used by warehouse

to pick/send orders

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Creating Main Form Query…

• Create query to join Customers, Customer Orders and Orders

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Creating Subform Query…• Create query to join Order Lines and Products

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Creating the Subform…• Open the form Wizard• Select the Sub Form Query from ‘Table/Query’

• Use all fields• Select ‘by Order Line’

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Creating the Subform…• Select ‘Datasheet’• Select ‘Standard View’• Open in ‘Design View’• Field label should be

meaningful:– Change Caption of Label– Change Name of Field

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Creating the Subform…• Change field order

to make logical sequence

• Change order in Design View

• Change Tab Order– Right Click

Available‘Areas’

Fields andcurrent order

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Creating the Subform…• Hide unneeded

columns– Order ID is not

needed in Subform as it is stated in Main Form

• In ‘View’ right click on the column

• Select ‘Hide Columns’

• Save form

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Creating the Subform…• Final form will look like this

– Field titles and order are as desired– All Order Lines records are shown as it is not

yet linked to the Main Form

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Creating the Main form…• Open the form Wizard• Select the Main Form Query form ‘Table/Query’

• Use all Fields

• Select ‘by Orders’– As we wish to view the

orders

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Creating the Main form…• Select ‘Column’ layout• Select ‘Standard’ style• Save form as “Order Details”

• Open in ‘Design View’

• Format fields and labels

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Linking Main and Sub• Extend the main

forms detail area• Move form so you

can see the objects window

• Select and drag the sub form in and drop

• Select the subform and open properties

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Creating the Main form…• Add header to ‘explain’

form• Add label to ‘explain’

Subform• With Main and Subform

Linked only records that are linked will be shown

• Save Form

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Result of Main and Subform…

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Tutorial Exercise: Music• Task 1: Use a form and sub-form to enter

data for Tracks and Artists