Database Reference
In-Depth Information
Figure 1.1
The Evolution of
Data Modeling.
Hierarchical
. A branch-leaf tree structure as shown in Figure 1.2
such that child tables can only have single parent tables. A child table
is completely dependent on the existence of its parent table. As a
result, one-to-many relationships are supported but not many-to-
many relationships. The primary disadvantage of a hierarchical struc-
ture is that everything must be accessed from the root node of the
tree. In Figure 1.2, accessing a Song would require retrieval of an Art-
ist and all of that artist's songs.
Figure 1.2
The Hierarchical
Data Model.
