Relational database, oracle and PL/SQL

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Relational Database

A relational database is a database that has a collection of tables of data items, all of which is formally described and organized according to the relational model. The term is in contrast to only one table as the database, and in contrast to other models which also have many tables in one database.

In the relational model, each table schema must identify a column or group of columns, called the primary key, to uniquely identify each row. Rows in one table can relate to a rows in another table by establishing a foreign key, a column or group of columns in one table that points to the primary key of another table. The relational model offers various levels of refinement of table organization and reorganization called database normalization. (See Normalization below.) The database management system (DBMS) of a relational database is called an RDBMS, and is the software of a relational database.

The relational database was first defined in June 1970 by Edgar Codd, of IBM’s San Jose Research Laboratory. Codd’s view of what qualifies as an RDBMS is summarized in Codd’s 12 rules. A relational database has become the predominant choice in storing data. Other models besides the relational model include the hierarchical database model and the network model.

Oracle

Oracle is an American multinational computer technology corporation headquartered in Redwood City, California, United States. The company specializes in developing and marketing computer hardware systems and enterprise software products – particularly its own brands of database management systems.

PL/SQL

PL/SQL is an imperative 3GL that was designed specifically for the seamless processing of SQL commands. It provides specific syntax for this purpose and supports exactly the same datatypes as SQL. Server-side PL/SQL is stored and compiled in Oracle Database and runs within the Oracle executable. It automatically inherits the robustness, security, and portability of Oracle Database.