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 as 
(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 
select sum(...)
CA Live API Creator
 updates 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 Creator
 increments 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
  1. In API Creator, select Manage, Rules, and click
    Create New Rule
  2. Select the
    rule type, the table to which it applies, and click
    Create Rule
  3. Define the parameters of the rule:
    Sum name
    The name of the sum rule. 
     Leave this field blank for the system default.
    The name of the parent table and column representing the sum result.
    You can associate this rule with a topic.
    Child entity/column
    Defines the child role (first combo box) and attribute (second combo box) being summed.
    For more information about the child role, see Database Connectivity.
    Child Qualification
    Boolean JavaScript expression designating the child rows that contribute to the sum.
    Syntax Notes:
    • JavaScript means you are using logical operators such as 
       for "and", 
       for "or".
    • Specify equals as "=" or "==".
    • Specify not equals as !=.
    • Use the
      , not 
    Child qualifications can include nulls, for example, the following qualification check null (or != null):
    kit_item_ident = null
    Select to activate the rule (The definition must be complete).
    Indicates whether you can optimize the rule by executing it in SQL instead of in JavaScript.
    Just In Time
    You can indicate formulas and aggregates as Just in Time (JIT) rules. You can define JIT rules on persistent attributes and on rules of type formula, sum, count, min and max.
    If the value in the database is null, 
    CA Live API Creator
    executes the rule on the first read, stores the value for that column in the database, and returns the value. To prevent
    CA Live API Creator
    from executing rules with null return values on every read, the rule should never return a null value.
  4. Click
    Activate and Close
    to return to the list of rules.
The sum rule is created.