DBMS: Relationship (Definitions)

"A logical linkage between two entities that describes how the entities are associated with each other." (Owen Williams, "MCSE TestPrep: SQL Server 6.5 Design and Implementation", 1998)

"A link between tables that references the primary key in one table to a foreign key in another table. The relationship line is represented in a database diagram by a solid line if referential integrity between the tables is enforced, or a dashed line if referential integrity is not enforced for INSERT and UPDATE transactions. The endpoints of a relationship line show a primary key symbol to denote a primary-key-to-foreign-key relationship or an infinity symbol to denote the foreign key side of a one-to-many relationship." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"In database design, a property that exists between two (or sometimes more) entities. The property may represent a state, a behavior, an action, or some other logical combination and usually has a verb phrase or prepositional phrase as its name. In some modeling techniques, each relationship has two directions of interpretation; for example, in a library application, considering the book and book copy entities, a book may be owned as one or more book copies, and a book copy must be of exactly one book." (Bill Pribyl & Steven Feuerstein, "Learning Oracle PL/SQL", 2001)

"A link between tables that references the primary key in one table to a foreign key in another table. In English Query, a relationship is an association between entities that describes what those entities have to do with one another." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"A relationship documents the business rule associating two entities. The relationship is used to describe how the two entities are naturally linked to each other." (Claudia Imhoff et al, "Mastering Data Warehouse Design", 2003)

"A connection between two entities that signifies the presence of a business rule." (Margaret Y Chu, "Blissful Data ", 2004)

"A connection between entities ties a parent entity to a child entity through the Primary Key in one entity to a Foreign Key in another." (Thomas Moore, "EXAM CRAM™ 2: Designing and Implementing Databases with SQL Server 2000 Enterprise Edition", 2005)

"A logical link between two entities that represents a business rule or constraint." (Sharon Allen & Evan Terry, "Beginning Relational Data Modeling" 2nd Ed., 2005)

"A social association or connection between two or more people." (Victor Isakov et al, "MCITP Administrator: Microsoft SQL Server 2005 Optimization and Maintenance (70-444) Study Guide", 2007)

"An association between two tables. For example, if an order contains several order items, there is a one-to-many relationship between Orders and OrderItems tables. Don't confuse this term with "relation."" (Rod Stephens, "Beginning Database Design Solutions", 2008)

"A link between tables that references the primary key in one table to a foreign key in another table." (Jim Joseph, "Microsoft SQL Server 2008 Reporting Services Unleashed", 2009)

"A real-world association among one or more entities. For example, “purchased” could be a relationship between customer and product." (Toby J Teorey, ", Database Modeling and Design" 4th Ed., 2010)

"The complete association among specific entity classes consisting of two or more relationship roles." (David C Hay, "Data Model Patterns: A Metadata Map", 2010)

"An association between entities." (Carlos Coronel et al, "Database Systems: Design, Implementation, and Management" 9th Ed., 2011)

"Defines how different entities are associated with each other. A relationship is defined by the keys: the primary key in the parent entity and the foreign key in the dependent entity." (Craig S Mullins, "Database Administration", 2012)

"The association of two or more entities; through this association, it expresses the business policy of the data model." (James Robertson et al, "Complete Systems Analysis: The Workbook, the Textbook, the Answers", 2013)

"A connection between two tables based on a shared field." (Faithe Wempen, "Computing Fundamentals: Introduction to Computers", 2015)

"Any connection between two or more variables. In research, there are many types of relationships, from simple contingencies to established causal relationships." (K  N Krishnaswamy et al, "Management Research Methodology: Integration of Principles, Methods and Techniques", 2016)

"A defined connection between the rows of a table or the rows of two tables. A relationship is the internal representation of a referential constraint." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)