Relational Database Management Systems


A relational database management system (RDBMS) is a program that lets you create, update, and administer a relational database. Most commercial RDBMS's use the Structured Query Language (SQL) to access the database, although SQL was invented after the development of the relational model and is not necessary for its use. 

The leading RDBMS products are Oracle, IBM's DB2 and Microsoft's SQL Server. Despite repeated challenges by competing technologies, as well as the claim by some experts that no current RDBMS has fully implemented relational principles, the majority of new corporate databases are still being created and managed with an RDBMS.

 RDBs organize data in different ways. Each table is known as a relation, which contains one or more data category columns. Each table record (or row) contains a unique data instance defined for a corresponding column category. 

One or more data or record characteristics relate to one or many records to form functional dependencies. These are classified as follows:
·        One to One: One table record relates to another record in another table.
·        One to Many: One table record relates to many records in another table.
·        Many to One: More than one table record relates to another table record.
·        Many to Many: More than one table record relates to more than one record in another table.
RDB performs "select", "project" and "join" database operations, where select is used for data retrieval, project identifies data attributes, and join combines relations.

RDBs have many other advantages, including:
·        Easy extendability, as new data may be added without modifying existing records. This is also known as scalability.
·        New technology performance, power and flexibility with multiple data requirement capabilities.
·        Data security, which is critical when data sharing is based on privacy. For example, management may share certain data privileges and access and block employees from other data, such as confidential salary or benefit information.


Yana said...

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Azie said...

nice. . .really interesting