Relation Database Terminology

Relation Database Terminology:

      A relational database is a database management system based on relational model of database. It is a set of tables containing a pre-defined data types. All the tables in a relational database are flat table. In this model relations are established among the table with the help of their common attribute. SQL is the standard user and application program interface to access the data in the relational database. In this database tables are known entity set, files, or relation depending upon the writer. You need to represent all data in table and each table represents a same kind of data.

Row or Tuple:

It represents all data required for a particular instance in entity. Each row is an entity is uniquely identified by declaring it has PRIMARY KEY or UNIQUE. The order o the rows is not significant, while retrieving the data.

Column or Attribute:

It represent one kind of data in a table. The column order is not significant when storing the data.

A Field:

It can be found at the intersection of row and a column. A field can have only one value, or may not have a value at all, the absence of value in Oracle is represented as NULL.

Relating Multiple Tables:

Each table contains data that describes exactly only one entity. Data about different entities is stored in different tables. RDBMS enables the data in one table to be related to another table by using the Foreign keys. A Foreign key is a column or a set of column that refer to a Primary key in the same table or another table.

Rational Database Properties:

Should not specify the access route to the tables, and should not reveal the physical arrange. The Database is accessed using Structured Query Language(SQL). The language is a collection of set operators.

Communicating with RDBMS:

  The Structured Query Languager is used to communicate with RDBMS.

Relation Database Terminology