masterdetail

Master-detail is a data relationship pattern in which one record acts as the parent (master) and one or more records act as the child (detail). The detail records depend on the master for identity and often for security, ownership, and lifecycle. In many implementations, the detail table contains a foreign key that points to the master, and the master controls or constrains the existence of its details. A common characteristic is cascade behavior: deleting the master typically deletes its associated details, ensuring referential integrity. By contrast, a lookup relationship allows the child to exist independently and does not imply the same tight coupling or cascade deletion.

Key features commonly associated with master-detail designs include referential integrity, where detail records cannot exist without a corresponding master; ownership and access rights that often flow from the master to its details; and the ability to summarize detail data on the master through roll-up capabilities, such as counting or aggregating detail records. In certain platforms, the master also determines the visibility of the detail records and can simplify management of related data.

Common use cases involve assemblies of items where a single parent aggregates multiple children, such as an invoice with line items, an order with order lines, or a project with tasks. The pattern is widely used in relational databases and in application platforms, with minor variations in constraints and feature sets. When choosing between master-detail and other relationships, considerations include dependency needs, lifecycle semantics, and performance implications.

In practice, master-detail is often contrasted with the simpler lookup relationship, where records remain more independent and do not automatically cascade deletes or share a single ownership model.