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Monday, July 18, 2011

What are the different data modeling concepts?

Data model is a conceptual representation of data structures. The data structures consist of data objects, relationship between data objects and rules that govern these operations. Often, analysis modeling begins with data modeling.
The inputs of data model comes from the planning and analysis stage. There are two outputs of the data model. First is an entity relationship diagram and second is a data document. The goal of the data model is to make sure that the all data objects required by the database are completely and accurately represented.

The different concepts of data modeling are:

- Data Objects are a representation of any composite information that is processed by software. A data object can be an external entity, thing, occurrence, event, role, an organizational unit, place or a structure. The description of the data object includes data object and its attributes. A data object contains only data.

- Data Attributes name a data object, describe its characteristics and sometimes make reference to another object. One or more attributes must be identified as a key which acts as an identifier.

- Relationships indicate the manner in which data objects are connected to one another.

- Cardinality of a relationship is the actual number of related occurences for each of the two entities. It defines the maximum number of objects participating in relationship. It does not indicate whether a data object should participate in relationship or not.

- Modality of a relationship can be 0 or 1. It is 1 if an occurrence of relationship is must. It is 0 if an occurrence of relationship is optional.

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