↕️ Hierarchical Data Model

Also known as HDM

Data can be retrieved easily due to the explicit links between the table structure
Referential integrity is always maintained. i.e. any changes made in the parent table are automatically updated in a child table
Promotes data sharing
It is conceptually simple due to the parent-child relationship
Database security is enforced
Quick access at root nodes
Efficient with 1:N relationships
A clear chain of command or authority
Increases specialisation
Clean results
High performance

If the parent table and child table are unrelated, the adding a new entry in the child take is difficult because additional entry must be added in the parent table
Complex relationships are not supported
Redundancy which results in inaccurate information
Change in structure leads to change in all application programs
M :N relationships are not supported
No data manipulation or data definition language
Lack of standards
Poor flexibility
Difficult to implement into a database
Communication barriers
Organisational disunity
Rigid structure

What does the N mean?

N means many
Example:
M : N = Many to Many

NOUN
1. disagreement and conflict within a group.