Concepts

Tasks

Settings

Defining Selection Criteria for a Purging Rule

Once you have defined the general characteristics of the purging rule, you can set up the criteria for filtering the objects to be purged.

Because purging rules are site-specific, the site is always an implied selection criterion. That is, a purging rule only deletes items for the site or sites to which it applies, regardless of the other selection criteria defined. Every filter criterion starts from the class of objects that you want to select (for example, the Work Request class). You must then select either an attribute or a relationship to use to filter the objects. In most cases, you will base the filter on an attribute (property) of the base class. For example, you might filter a group of work requests based on the WorkRequestStatus attribute. However, you might also use an attribute owned by a related class.

Filter Groups

You can create filter groups to specify which criteria are evaluated together. This grouping, when combined with logical operators, determines how criteria are evaluated. Changing the group to which a criterion belongs often yields very different results.

Each filter group is identified by a number. The first criterion that you create is assigned to filter group “0”. By default, each new criterion is added to the same filter group. You can change the group to which a criterion is assigned by entering another group number in the Logical group box on the Filter Criterion dialog. You can add any criterion to any filter group. For example, you might want to evaluate all criteria based on the same attribute within the same group.

Relationships Between Filter Groups

Boolean logic allows you to define the relationship between filter criteria and filter groups. In Boolean searching, an AND operator between two criteria (for example, Title contains “pear” AND “apple”) returns records where the Title contains both values, not just one of them. An OR operator between two criteria (for example, Title contains “pear” OR “apple”) returns records that contain either of the words.

In some cases, two operators allow you to define the relationship between groups and between the criteria within a group. These are:

•	AND within a group, OR between groups

•	OR within a group, AND between groups

The default choice is AND within a group, OR between groups. Because each group typically contains only criteria for the same attribute, in most situations it is not necessary to change the default operator.

For example, the following criteria and the AND within a group, OR between groups setting:

Group	Criteria
0	A = 3
1	A = 7
2	B > 11
2	B < 21

are evaluated as: A=3 OR A=7 OR (B>11 AND B<21).

If the logical operator setting is changed to OR within a group, AND between groups and the groups the criteria belong to:

Group	Criteria
0	A = 3
0	A = 7
1	B > 11
1	B < 21

the set is now evaluated as: A=3 OR A=7 AND (B>11 OR B<21).

To Define Section Criteria for a Purging Rule

1.	On the Purging Rule dialog, select the Selection Criteria tab.

2.	Click New. The Filter Criterion dialog appears.

3.	Identify whether objects will be filtered according to an attribute or a relationship with another class. Most purging rules are based on an attribute, for example, the active status of a resource transaction. For more information, see:

•	Creating a Filter Criterion Based on an Attribute

•	Creating a Filter Criterion Based on a Relationship

As you add filter criteria, the Selection Criteria tab displays the complete filter.

4.	If you wish, you can change the relationship between the filter groups from the default (ANDed with a group, ORed between groups) to ORed within a group, ANDed between groups.

5.	When a purging rule is executed, the selection criteria is translated into an SQL select statement. You can preview the SQL to be produced by clicking View SQL. You cannot alter the generated SQL.

6.	You can also click Preview to test the result of applying the selection criteria to the database.