Structures - Hierarchical

A tree structure, where each item has only one "parent". Developed in 1960's to organise the data for the US space program and when tape drives were the primary data storage medium. Still in widespread use in the US as legacy systems, for example McDonnell Douglas Corporation who manufacture major fighter aircraft including the Air Force F-15, Navy F-18.

Terms:

• Node: points in a hierarchical database
• Parent/Child node - each child node may have only one parent, though each parent may have many child nodes.

Features:

• Parent nodes must be created before child nodes are added
• Deleting a parent node will delete all child nodes.
• Only one parent per child, no relationships can exist between the child nodes.

Examples:

• IBM's Information management system.
• The MS-DOS file structure.

Ref: McFadden,F & Hoffer J (1994) p200, 490-

[Rev: 24/9/98] Jun-97 © 1997-98 V/2-Com (Verhaart), P O Box 8415, Havelock North, New Zealand.