Data Models: Data models describe how data is connected to each other and how that process and stored inside the system. Hierarchical Model: The hierarchical data model is like trees structurethat present data to users in tree structure. In hierarchical model each record looks like an organizational chart with one top level segment called root. The upper segments are connected logically to the lower segments like as parent and child relationship, and a parent segment can have many children but a child segment can have only one parent. In other words the hierarchical model design is that uses a one to many relationships or links anumber of disparate elements to owner or parent records. Network Model: Network model data allow the network …show more content…
There are several different levels of data modelling such as; • Conceptual data model • Logical data model • Physical data model Conceptual Data Model: Conceptual model is high level model that identifies the higher level relationship between different entities. . Its created by gathering all the business requirements from various sources like business analysts, discussion, documents, management experts and end users that do reporting on the database also its includes all major entities and relationships. Logical Data: Logical data describes the data in as much details as possible and it does include all entities and relationships among them. In logical data all attributes for each entity and the primary key and foreign keys are specified. Physical Data Model: Physical data model about how data will form in the database. . It will specify all the column and tables. This database shows all the structures of tables that include, column of data type, column of names, column of constrains, relationship between tables, primary key and foreign key. The foreign key is use to identify relationship between tables. Feature and …show more content…
Entities are representing by square or round corner. Entity Relation Diagram (ERDs): Entity relationship diagram is a design tool that represent the data system in graphical. ERDs provide a high level theoretical data model and composed of entities, attributes and relationships. A user has to connect a table with other tables to create a relationship between them. Entity attributes and identifiers: Entity attributes are property of an entity that can have any value from domain and they have any number of attributes. Database is used for to store information then user can use it when its need in order to achieve this task user has to identify each entity. Attributes can have different values than any other entity. There are two types of entity attributes; Transient and Persistent. Persistent attribute is persisted and derived from database whereas the value will not be persisted and derived in a transient attribute. Relationship types: there are three types of relationships One –to –one: In one-to-one relationship both side tables will have one record on both sides such as; Husband
The Data XML contains the data that needs to be added/updated to/deleted from the Database.
Conceptual schema at the conceptual level describes the structure and constraints for the whole database for a community of users. These uses a conceptual or an implementation data model.
There are two types of data. They are unstructured and multi-structured. Unstructured data comes from information that isn’t organized or easily interpreted by traditional databases or data models. This is usually in text format.
These are covered briefly in appendices in the text. The relational model was first proposed by E.F. Codd in 1970 and the first such systems were developed in 1970s. The relational model is now the dominant model for commercial data processing applications. The relational model can be used in both conceptual and logical database design. The basic structure in the model is a table .Tables consists of rows and columns. Relationships in the relational model are represented implicitly through common attributes between different relations.
As defined by Kroenke Database is an integrated, self-describing collection of related data. Data is stored in a uniform way, typically all in one place- for example, a single physical computer. A database maintains a description of the data it contains and the data has some relationship to other data in the databa...
In the world of database technology, there are two main types of databases: SQL and NoSQL—or, relational databases and non-relational databases. The difference speaks to how they’re built, the type of information they store, and how they store it. Relational databases are structured, like phone books that store phone numbers and addresses.
...el that's closely aligned with the software program’s object model. Obviously, an OODBMS may have a physical data model optimized for those types of logical data model it needs.
iii)Model of the information system: This is Architect's view.this describes in step 2 where row 2 describe business functions and row 3 decribe collect and maintain information.
meta data - data about the data itself, such as logical database design or data dictionary definitions
For this coursework two kinds of data models can be used. The object oriented data model, Object Oriented Database Management System(OODBMS), or the relational data model, Relational Database Management System(RDBMS). The differences between these two models and the data model to be used are described in this chapter.
Concepts are determined by attributes and definitions of key terms. Relationships are determined by concepts, and data derived from the various source vocabularies.
A database is a structured collection of data. Data refers to the characteristics of people, things, and events. Oracle stores each data item in its own field. For example, a person's first name, date of birth, and their postal code are each stored in separate fields. The name of a field usually reflects...
Later in the chapter it shows examples of the models created for the business, application and technology layer. Gives us specific techniques and terms needed that are used in the models.
A datum - data unit - is a symbol or a set of symbols used to represent something. The relationship between symbols and what they represent is the essence of what we mean by information. Therefore, the information interpreted data - data supplied by semantics. Knowledge of data refers to the practical use of the information. Although information can be transported, stored or shared ...
MODELLING - modelling is defined as a process of representing a model which includes its construction and working, it is an act of building a model. A model can be described as a program that represents a real life system in a virtual environment and helps in the analysis and predictions of changes of the system. It does so by using mathematical formulas and calculations to predict the properties of a system.