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Essay about Data Basing 101

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Conceptual Data Models for Database Design

Database Design Process

The database design process consists of a number of steps listed below. We will focus mainly on step 2, the conceptual database design, and the models used during this step.

Step 1: Requirements Collection and Analysis ▪ Prospective users are interviewed to understand and document data requirements ▪ This step results in a concise set of user requirements, which should be detailed and complete. ▪ The functional requirements should be specified, as well as the data requirements. Functional requirements consist of user operations that will be applied to the database, including retrievals and updates. ▪ Functional requirements can be documented using …show more content…

For example, if you wish to store the Company Location, unless you will use the atomic information such as Postal Code, or City separately from the other Location information (Street Address etc) then there is no need to subdivide it into its component attributes, and the whole Location can be designated as a simple attribute.

▪ What are examples of other composite attributes?

Single-Valued vs. Multi-valued Attributes

▪ Most attributes have a single value for each entity, such as a car only has one model, a student has only one ID number, an employee has only one data of birth. These attributes are called single-valued attributes. ▪ Sometimes an attribute can have multiple values for a single entity, for example, a doctor may have more than one specialty (or may have only one specialty), a customer may have more than one mobile phone number, or they may not have one at all. These attributes are called multi-valued attributes. ▪ Multi-valued attributes may have a lower and upper bounds to constrain the number of values allowed. For example, a doctor must have at least one specialty, but no more than 3 specialties.

Stored vs. Derived Attributes

▪ If an attribute can be calculated using the value of another attribute, they are called derived attributes. ▪ The attribute that is used to derive the attribute is called a stored attribute. ▪ Derived attributes are not stored in the file, but can be derived when needed from the stored

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