Explore chapters and articles related to this topic
Static Testing the Logical Design
Published in William E. Lewis, David Dobbs, Gunasekaran Veerapillai, Software Testing and Continuous Quality Improvement, 2017
William E. Lewis, David Dobbs, Gunasekaran Veerapillai
Each entity is a table divided horizontally into rows and columns. Each row is a specific occurrence of each entity, much like records in a file. Each column is an attribute that helps describe the entity. Examples of attributes include size, date, value, and address. Each entity in a data model does not exist by itself; it is linked to other entities by relationships. A relationship is an association between two or more entities of interest to the user, about which the application is to maintain and report data. There are three types of relationships: a one-to-one relationship links a single occurrence of an entity to zero or one occurrence of another entity; a one-to-many relationship links one occurrence of an entity to zero or more occurrences of an entity; and a many-to-many relationship links many occurrences of an entity to many occurrences of an entity. The type of relationship defines the cardinality of the entity relationships. See Appendix G10, “Database Testing,” for more details about data modeling.
Property modelling in the AECO industry
Published in Pieter Pauwels, Kris McGlinn, Buildings and Semantics, 2023
Mathias Bonduel, Pieter Pauwels, Ralf Klein
When creating a relational database for this ERD, all entities (rectangles) will result in single tables, and the associated attributes (ellipses) are included as columns in this table. The identifying attributes define which columns are used as primary keys. Relationships (diamonds) find their way into the database definition either as foreign keys in the existing tables (one-to-one and one-to-many relationships) or as extra ‘intermediate’ tables with foreign keys pointing to the associated tables (many-to-many relationships).
Data Analysis and Design
Published in Sharon Yull, BTEC National for IT Practitioners: Systems units, 2010
There are similarities between the two models; however, instead of using a single-parent tree hierarchy, the network model uses a set theory to provide a tree-like structure. Child tables can have more than one parent, thus supporting many-to-many relationships.
Development of a worldwide ferry safety database utilizing relational database approach
Published in Journal of Transportation Safety & Security, 2019
Siyu Xu, Hao Hu, Roberta Weisbrod
An entity is mapped to a table in a straightforward way, where attributes of the entity are transformed into the fields of the table and the primary key used to uniquely identify each record in the table is bold and underlined. With respect to relationships, a typical way to handle the one-to-many relationship is to insert a foreign key into the table that represents the “many” side of the relationship. And a many-to-many relationship needs to be transformed into bilateral one-to-many relationships by creating a separate bridge table. The attributes of such a table contain the primary keys of participating entities and the descriptive attributes of the relationship.