What is Database ?
A database is a collection of data/information, organized together in such a manner so that they can accessed easily and successfully. Database may be of many types such as Flat files, Relational Database, Distributed database etc. Relational database approach is widely being used today, in such a database approach data/information are organized in forms of tables. To access data from database we use SQL (Stander Query language). It is data manipulation language used to manipulate data from the database. Its basic operation are SELECT, INSERT, UPDATE, and DELETE.
Relational Database Terminology
A relational database is a database management system based o n 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.
Database Table Description
Rows are known as tuples, entity or records, Each row in a table is distinct to each other and having the same kind of data. Columns in a table are known as attributes, each column has a unique name. Column name should be descriptive they should define the properties of the entity or table. Each column have a pre defined data type such as integer, varchar, character, date etc. The ordering of rows and column are irrelevant to the functionality of database.
Each table must have a primary key. This is a key which is used to identify a record uniquely in a table. If primary key of one table is being used in another table to establish a relation then primary key of one table is foreign key in other lable.
Ralation Among Table
Posted on: October 14, 2010 If you enjoyed this post then why not add us on Google+? Add us to your Circles