Wednesday, April 29, 2009

What Is a Relational Database?

A database is a collection of permanently stored data that is:

  • Logically related (the data was created for a purpose).
  • Shared (many users may access the data).
  • Protected (access to the data is controlled).
  • Managed (the data integrity and value are maintained).

The Teradata RDBMS is a relational database. Relational databases are based on the relational model, which has its foundation in the mathematical theory of sets. The relational model uses and extends many principles of set theory to provide a disciplined approach to data management.

Relational databases present data as of a set of tables. A table is a two-dimensional representation of data that consists of rows and columns. According to the relational model, a valid table does not have to be populated with data rows, it just needs to be defined with at least one column.

Tables are logically related to each other by a common field, so information such as customer telephone numbers and addresses can exist in one table, yet be accessible for multiple purposes. The example below shows customer, order, and billing statement data, related by a common field (Customer ID).

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