Structures in the relational model

The relational database model contains the following specific relations:

1. Table (File, Relation)
2. Record (Row, Tuple)
3. Field (Column, Attribute)

A relational database can be visualised as a table:

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EAGLET is implemented as a single table where the set of terms is represented as a set of records (table rows) and all term attributes are mapped to record fields (table columns).

The relations between the records (`vcards' for `virtual term record cards') are expressed by key mapping operations:

• candidate key: any unique identifier for a record.
• primary key: the candidate key you choose to use.
• compound key: a key made up of more than one field (currently not used in EAGLET).
• foreign key: a field in one table that points to a record in a different table (currently not used in EAGLET).