Database Models

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Database Models by Mind Map: Database Models

1. Flat File

1.1. Simplest model for storing data. Consists of a single, two-dimensional table of data elements.

1.1.1. Most databases display records as rows in a table or as forms. A record refers to a collection of data fields. A record has a template referred to as a record type and contains field names, but no data. Also, a data contained record is called a record occurance.

1.1.2. The smallest unit of meaningful information is called a field. A field name is designed to describe the field's contents. There are two types of length fields known as variable-length fields and fixed-length fields. Variable-length field expands to fit the data you enter, up to a max number of characters Fixed-length fields contain a predetermined number of characters.

2. Relationship Databases

2.1. Hierarchial Database

2.1.1. Allows one-to-one and many-to-many relationships A one-to-one relationship means one record is related to many records For example, in the case of a CD store, a customer can order many albums. Also, an album has only one description. A many-to-many relationship means that one record in a specific record type can be related to many records in another record type. For example, one album contains many songs, and a song can be included in a number of different albums Rarely used in today's businesses, but are still used for specific applications.

2.2. Network Database

2.2.1. Combines both one-to-one and many-to-many

3. Relational Database

3.1. Stores data in a collection of related tables.

3.1.1. Each table has a sequence of records, similar to that of a flat file. Two tables can be joined by similar fields. Tables are essentially independent, but can be joined to complete a particular task.

4. Dimensional Database

4.1. Also referred to as a multidimensional database, organizes relationships over three or more dimensions.

4.1.1. Each field is contained within a cell that can be accessed from a query or from following a relationship. Offers a simple way to visualize data and formulate queries.

5. Object Database

5.1. Also referred to as an object-oriented database, stored data as objects, which can be grouped into classes and defined by attributes and methods.

5.1.1. Can easily store data about different types of orders. For example, a class called orders holds data and methods common to all types of orders. A class called web orders is common to only orders placed on the web.

6. Object-relational Database

6.1. Used to describe a variety of technologies that combine object-oriented and related concepts. Described as an attempt to add OO-ness to tables.

6.1.1. Have the flexibility to store unique types of data and program code necessary to access that data. For example, a relational database sends a file name to an external player, but an object-relational database can store the song data and the routine to play it. Like iTunes.