Data Models in DBMS

Database Models :

 A Database model defines the logical design of database, including the relationships and constraints that determine how data can be stored and accessed. Individual database models are designed based on the rules and concepts of whichever broader data model the designers adopt. Most data models can be represented by an accompanying database diagram. In Database design, three models are commonly used which are :

1. Hierarchical Model
2. Network Model
3. Relational Model

1. Hierarchical Model : In this model each entity has only one parent but can have several children. The hierarchical model organizes data into a tree-like structure, where each record has a single parent or root. Sibling records are sorted in a particular order. that order is used as the physical order for sorting the database. This model is good for describing many real-world relationships.

2. Network Model : The network model builds on the hierarchical model by allowing many-to-many relationships between linked records, implying multiple parent records. Based on the mathematical set theory, the model is constructed with sets of related records. Each set consists of one owner or parent record and one or more member or child records. A record can be a member or child in multiple sets, allowing this model to convey complex relationships.

3. Relational Model : In this model, data is organised in two-dimensional tables called relations, each of which consists of columns and rows. Each column lists an attribute of the entity, together, the attributes in a relation are called a domain. A particular attribute or combination of attributes is chosen as a primary key that can be referred to in other tables,when it's called a foreign key. Each row, also called a tuple, includes data about a specific instance of the entity. The model also accounts for the types of relationships between those tables, including one-to-one, one-to-many, and many-to-many relationships.

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