1. Hierachical
1.1. Data structure
1.1.1. One to many or one to one relationship.
1.1.2. Based on parent child relationship.
1.2. Data Manipulation
1.2.1. Does not provide an independent stand alone query interface
1.2.2. Retrieve algorithms are complex and asymmetric
1.3. Data Integrity
1.3.1. Cannot insert the information of a child who does not have any parent.
1.3.2. Multiple occurrences of child records which lead to problems of inconsistency during the update operation.
1.3.3. Deletion of parent results in deletion of child records
2. Network
2.1. Data structure
2.1.1. Allowed the network model to support many to many relationships.
2.1.2. A record can have many parents as well as many children
2.2. Data Manipulation
2.2.1. Use CODASYL (Conference on Data Systems Language)
2.2.2. Retrieve algorithms are complex and symmetric
2.3. Data Integrity
2.3.1. Does not suffer from any insertion anomaly.
2.3.2. Free from update anomalies
2.3.3. Free from delete anomalieis
3. Relational
3.1. Data structure
3.1.1. Ono to one. One to many. Many to many relationships
3.1.2. Based on relational data structures
3.2. Data Manipulation
3.2.1. Relational database are what brings many sources into a common query (such as SQL)
3.2.2. Retrieve algorithms are simple and symmetric
3.3. Data Integrity
3.3.1. Does not suffer from any insertion anomaly.
3.3.2. Free from update anomalies
3.3.3. Free from delete anomalies