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Data Modeling
Relational Model

The most commonly understood data model today is the relational model, where all data is defined in terms of tables and columns. We will not define the relational model here, but will note that RDM defines a database using SQL, the predominant relational database language. Relationships in a pure relational model are defined by associating common columns between two tables through what are called primary and foreign keys. Indexing is a common method used to optimize relational queries.

Network Model

Beneath the relational model in an RDM database is a network model, where all data is defined in terms of record types ("tables") and fields ("columns"). Fields may be indexed, and record types may have set relationships between them, which are defined as one-to-many, owner/member relationships. One record is an instance of a record type. In relational terminology, a row is a single line in a table. RDM uses the set construct to implement primary and foreign key relationships.