Relational Database Management System (RDBMS)

**What is the definition of Relational Database Management System (RDBMS)?
What do we know about it?

      A relational database management system (RDBMS) is a database engine or system that is based on the relational model specified by Edgar F. Codd, father of modern of relational database design- in 1970. Actually, the software for a relational database is called Relational Database Management System which controls reading, writing, modifying, and processing the information stored in the databases. What is relational database? Relational database is a database storing information about both the data and how it is related. According to each database's 
relational model (database schema), according to the design the data is formally described, illustrated  and organized, controlled, structured.  Organizations often want to store and retrieve, regain information about people and about their location and how to contact them. Often many people live or work at a variety of addresses. So, recording and regaining them becomes important—relational databases are good for supporting these kinds of applications.  
  
            The most important relational database features consist of an ability to use tables for data storage while maintaining & enforcing certain data relationships. Most modern commercial & open-source database applications are also relational in nature.

Relationships continue living both among the columns within a table and among the tables. These relationships capture three logical forms: one-to-one, one-to-many, or many-to-many. Most relational databases are designed in this way that there is only one value per cell (an intersection of a column and row); in this design pattern, there are only one-to-one relationships within a table. Each table is named according to the data it contains, such as people or addresses.

           Edgar F. Codd, a British computer scientist with IBM published “A Relational Model of Data for Large Shared Data Banks” in 1970. The renowned paper attracted little interest. Few people understood how Edgar F. Codd’s innovative & pioneering work would describe the basic rules for relational data storage. The basic rules can be facilitated as:
     A. Data must be stored & presented as relations, that is, tables having relationships with each other, e.g. primary/ foreign keys.
    B. To control the data stored in the tables, a system should provide rational operators- code enabling the relationships between two entities.
        There was another paper of Codd which he published. This paper outlined the 12 rules. The entire database must follow all the rules to quality as relational. Though many modern database systems don't follow all the 12 rules, they are considered as relational. It is because the modern database systems confirm to at least 2 of the 12 rules.

     Most modern commercial and open-source database systems are relational in nature. They contain well-known applications, e.g. Oracle DB (Oracle Corporation); SQL Server (Microsoft) and MySQL and Postgres (open source).