Microsoft SQL Server 2008 R2 810-08230 Benutzerhandbuch

An entity can also have any number of domain-based attributes whose values are mem-

bers of another related entity . In the example in Figure 7-1, the ProductSubCategory attribute 
is a domain-based attribute . That is, the ProductSubCategory codes are attribute values in the 
Product entity, and they are also members of the ProductSubCategory entity . A third type of 
attribute is the file attribute, which you can use to store a file or image. 

You have the option to organize attributes into attribute groups . Each attribute group con-

tains the name and code attributes of the entity . You can then assign the remaining attributes 
to one or more attribute groups or not at all . Attribute groups are securable objects . 

You can organize members into hierarchies . Figure 7-2 shows partial data from two types 

of hierarchies . On the left is an explicit hierarchy, which contains all members of a single enti-
ty . On the right is a derived hierarchy, which contains members from multiple, related entities . 

Product hierarchies

In the explicit hierarchy, you create consolidated members to group the leaf members . For 

example, in the Geography hierarchy shown in Figure 7-2, North America, United States, and 
Bikes are all consolidated members that create multiple levels for summarization of the leaf 
members . 

In a derived hierarchy, the domain-based attribute values of an entity define the levels. For 

example, in the Category hierarchy in the example, Wholesale is in the ProductGroup entity, 
which in turn is a domain-based attribute of the ProductCategory entity of which Compo-
nents is a member . Likewise, the ProductCategory entity is a domain-based attribute of the 
ProductSubCategory entity, which contains Forks as a member . The base entity, Product, 
includes ProductSubCategory as a domain-based attribute . 

Regardless of hierarchy type, each hierarchy contains all members of the associated enti-

ties . When you add, change, or delete a member, all hierarchies to which the member belongs 
will also update to maintain consistency across hierarchies . 

A collection is an alternative way to group members by selecting nodes from existing 

explicit hierarchies, as shown in Figure 7-3 . Although this example shows only leaf members, 
a collection can also contain branches of consolidated members and leaf members . You can 
combine nodes from multiple explicit hierarchies into a single collection, but all members 
must belong to the same entity .