Cube-Based MDX Calculations - Microsoft SQL Server 2008 Analysis Services - page 200

NOTE
The Scope statement is static: It is evaluated just once—when the script is loaded in
the cube—and is not reevaluated for each query. We highly recommend using the
power of the Scope operator and putting the more computation-intensive expressions in
the Scope operator or in the < sub_cube_expression > of the assignment operator rather
than in the rightmost part of the assignment.

When you define an assignment operator inside of a Scope statement, you can use the
This operator to assign an expression to the whole subcube defined by the Scope state-
ment.

Nested Scope Statements
You can define a Scope statement inside another Scope statement to create nested Scope
statements. (Conceptually, this is true even for an initial Scope statement created inside
the scope of a whole cube.) A nested Scope statement inherits some of the attributes from
a parent Scope statement. The rules of inheritance are somewhat similar to the rules of
coordinate overwrites and of strong relationships (see Chapters 10, “MDX Concepts,” and
11, “Advanced MDX”). Both sets of inheritance rules depend on the relationships
between attributes, but differences between the rules exist and are worth discussing. (For a
deeper discussion about attribute relationships, see Chapter 5, “Dimensions in the
Conceptual Model.”)

. If a subcube definition of a nested Scope statement explicitly specifies an attribute, it

overwrites the subcube's coordinate that corresponds to that attribute. For example,
if you have the following Scope statements, the Country attribute USA changes to
Canada , and the subcube that corresponds to stores in Canada takes on the value 1 :

Scope ([Store].[Stores].[Store Country].[USA]);
Scope ([Store].[Stores].[Store Country].[Canada]);
//The scope is on [Store].[Stores].[Store Country].[Canada]
This = 1;
End Scope;
End Scope;

. An attribute specified by a nested Scope statement does not overwrite its related (on

top of the current one) attribute. This is the primary difference with rules for coordi-
nate overwrites.

For example, the following Scope statements, in which the parent statement has a
slice on the Country attribute and the nested Scope statement has a slice on the
State attribute, do not overwrite the attribute Country , which is related to the State
attribute. They assign the value 1 to the subcube that corresponds to the
CrossJoin([Store].[Stores].[Store Country].[USA], [Store].[Stores].[Store
State].[WA]) set.