If you have defined the structure of an entity or link type but only a subset of
records in the tables are applicable to the type, you must define the conditions for when a
record will be used in the type. For example, in the Accounts Example 3 database, if you
want to define three account types all originating in the Account table, you will need to
set the conditions to distinguish each type.
To add type filters:
-
Click on the Filters tab on the Type Structure
dialog.
-
All of the fields used within the type are listed in the grid so you can add
conditions to any of these fields. Click in the required grid box and click
Browse to display the Field Condition dialog.
-
Enter the conditions
you require and click OK.
The origin of the field currently selected in the grid is displayed in the
Field details area below the grid. This may help to determine what
conditions you need to apply.
You can add conditions on as many fields as you like, but only one condition
per field. If you add conditions on multiple fields, all of the conditions
must be met.
You can also define a filter by setting the status of a relationship on the
Structure page to be Acts as a Filter. This means that the relationship
itself acts as a filter. For example, in the Accounts Example 3 database,
there are three tables involving transactions: Transactions,
CreditCardPayment and CheckPayment. Data for all transactions appears in the
Transactions table and the remaining two tables provide more information for
each transaction type. When defining the type Check Transaction, the
Transactions and CheckPayment tables will be used in the type structure. The
relationship between these tables can act as a filter to use only the subset
of records in the Transactions table that are also found in the CheckPayment
table, that is transactions of type Check. Defining a relationship to act as
a filter means that you do not have to define the filter of the Filters
page.
To define a relationship to act as a filter, right-click on the relationship
and select Acts as a Filter. The relationship line will become red.