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The following figure shows the hierarchical data model:

                                                                  CEO




                                          Marketing                                      Sales


                            Digital         Brand         Market      International      Retail       Corporate
                                                          Research


                                                                        East Coast

                 In the figure, “CEO” is the main category, like the trunk of a tree. It has two main branches: “Marketing”
                 and “Sales”. Each of these branches then further divides into more specific types, like “Digital”, “Brand”, and
                 “Market Research” under “Marketing”. This setup shows how one category can have several subcategories,
                 like a family tree.

                 Network Data Model

                 The Network Data Model allows multiple records to be linked to a central master file. While offering greater
                 flexibility  in  data  organisation,  this  model  can  present  challenges  in  management  compared  to  simpler
                 models.

                 The following figure shows the network data model:

                                                                University




                                                                                        Computer
                                       Maths Department
                                                                                       Department




                                      Library                    Seminar                  Computer Lab


                 In the figure, “University” stands as the starting point, with two branches: “Maths Department” and “Computer
                 Department”.  “Maths  Department”  has  three  sub-branches,  while  “Computer  Department”  has  two.  As
                 mentioned earlier, this model allows multiple parents, so “Seminar” and “Computer Lab” have two parents
                 each: “Maths Department” and “Computer Department”.

                 Relational Data Model

                 The relational data model is built on the concept of establishing relationships between two or more tables
                 within the same database. It is the most widely used database model, introduced by Edgar F. Codd in 1970. In
                 this model, data is organised into tables, each consisting of rows and columns. Each row represents a record
                 or entity, while each column represents a specific attribute or field of that entity.

                 The relational model is characterised by its ability to relate data across different tables using common fields,
                 hence the name “relational database model.” These relationships help maintain data integrity and enforce
                 constraints such as referential integrity.



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