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Chapter 2: The dTIMS CT Database
following diagram illustrates how a section perspective relates to locations along the road elements
and how to conceptualize the data in the perspective table.
Perspectives • Repeating Point Type
Defines a set of point elements where more than one element can exist at any particular location. This
perspective allows agencies to store things such as accidents or signs. The following diagram
illustrates how a repeating point perspective relates to locations along the road, elements and how to
conceptualize the data in the perspective table.
Perspectives • One to Many Type
Defines a set of elements such as maintenance activities, where one element in a source perspective
relates to many elements in this perspective. The following diagram illustrates how a section
perspective relates to locations along the road, elements and how to conceptualize the data in the
perspective table.
In a one-to-many relationship, the connecting text only attribute must contain only unique values. A
record in Perspective A can have many matching records in Perspective B, but a record in Perspective
B has only one matching record in Perspective A.
An Example: one vendor could supply more than one product, but each product has only one vendor.
This type of perspective is not available to Stripmaps.
Perspectives • Many to One Type
A many-to-one relationship is where one entity (typically a column or set of columns) contains values
that refer to another entity (a column or set of columns) that has unique values.
In relational databases, these many-to-one relationships are often enforced by foreign key/primary key
relationships, and the relationships typically are between fact and dimension tables and between levels
in a hierarchy.
Foreign key is the link between two tables. Given a value from a row in one table you can access
another table to find the row with related data.
NJDOT Deighton dTIMS CT User Manual 23