Sum Rule Type
Sum Rule Type
Sum rules are derivation rules that declare a parent attribute to be maintained as the sum of a designated child role's summed attribute, with an optional qualification to filter child objects. Parent reference names are derived from foreign key relationships.
For example, to derive the balance as the sum of the unpaid order totals:
Derive balance assum(purchaseorderList.amount_total where paid=false)
Use sum rules instead of events. The impact on performance is small. Adjustment is by way of one-row updates instead of expensive aggregate SQLs, like
CA Live API Creatorupdates the value of the attribute to reflect the sum of the specified attribute in the child objects whenever necessary. This includes adding and removing child objects from the parent object, as well as modifications to the children objects that change their qualification in the sum or the summed value. Sum processing is triggered by changes to the child. For example, when you add a new (qualifying) child to the parent,
CA Live API Creatorincrements the sum attribute by the child's amount.
You can view the changes in the log.
Best Practice:To maintain high performance, sum values are assumed to be correct on disk. For proper operation, if you define new sums on existing data, initialize these using SQL tools.
For more information:
Create a Sum Rule
- In API Creator, select Manage, Rules, and clickCreate New Rule.
- Select theSumrule type, the table to which it applies, and clickCreate Rule.
- Specify equals as "=" or "==".
- Specify not equals as !=.
- Use theattrName, notrow.<attrName>.
- ClickActivate and Closeto return to the list of rules.
The sum rule is created.