What are the differences between hierarchical, network and relational data models?

Question

Please tell me what is difference between hierarchical, network and relational data models?

Answer 1

分层模型

1.One to many or one to one relationships.
2.Based on parent child relationship.
3.Retrieve algorithms are complex and asymmetric
4.Data Redundancy more

网络模型

1.Many to many relationships.
2.Many parents as well as many children.
3.Retrieve algorithms are complex and symmetric
4.Data Redundancy more

关系模型

1.One to One,One to many, Many to many relationships.
2.Based on relational data structures.
3.Retrieve algorithms are simple and symmetric
4.Data Redundancy less