Relational data model:
- There is one data structure, the relation, which is defined in terms of attributes, tuples, primary keys, foreign keys and domains.
- Data is manipulated by a non-procedural language (SQL), a table at a time.
- There are two inherent integrity rules: entity and referential integrity.
Network data model:
- The data is defined as record types and set types.
- Data manipulation is by a series of database specific functions embedded in some host language.
- There is automatic support for certain forms of referential integrity.
In terms of the relational model, describe the following:
- In the relational model there is only one data structure, the relation.
- A relation is a table which is defined in terms of attributes, tuples, primary keys, foreign keys and domains.
- Data manipulation is conducted using a series of eight operators – relational algebra.
- The main operators are restrict, project and join. Others are product, union, intersection, difference and division.
- Data integrity is enforced via the entity and referential integrity rules.
- These two rules are inherent since every relational database should demonstrate adherence to these two rules.