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Many-to-Many Relationships

Last updated Feb 9, 2024

In the realm of data warehousing, the concept of many-to-many relationships is pivotal, especially when it comes to understanding the nuances behind the purchase or sale of an item. Such relationships depict a scenario where a sale might be linked to multiple reasons, and conversely, a sales reason could be associated with various sales. This dual linkage is a core aspect of many-to-many relationships.

In the context of systems analysis, these relationships are a form of cardinality. They describe interactions between two entities (let’s call them A and B), where entity A might have multiple corresponding entities in B and vice versa. This relationship is not just theoretical but has practical applications in specific modeling scenarios, particularly in SSAS and the Bus Matrix framework.

# Illustrative Example

Referenced from Many-to-many (data model) - Wikipedia

Consider the relationship between Authors and Books. An Author can pen multiple Books, while a Book might be co-authored by several Authors.

This Author-Book relationship is effectively represented as a pair of one-to-many relationships, bridged together through a junction table.

For an expanded exploration, see Many-to-Many-to-Many Relationship (two times many).

Created 2023-12-19