Relational Database Study Guide

1

Data is stored in separate tables this is the idea of a relational database.Each table stores data about a single individual.There are some rules required for relational database tables.

Every row must be constructed in the same way, that is each column must contain data of just one data type.

One column,or a combination of columns,must be able to make each row of the table unique.

This column or combination of columns is called the PRIMARY KEY.

There is no rule about the sequence of rows in a table.

There is no rule about the order of the columns.

No 2 rows in a relation can be identical.

The tables of a relational database are linked through relationships.Relationships are produced by having repeated fields.A field repeated from another table is called a FOREIGN KEY.

A non-relational database is any database that does not carry out the relational

Data structure-In order to use unstructured data that does not fit neatly into rows and columns the non relational databases are designed to do this.As most of the data generated is unstructured this is a definite requirement.

Scaling-by taking advantage of cheap ,commodity servers the system can be scaled horizontally.

You don't have to pay any software licensing fees in advance as they are an open source.

In comparing the two ,the limitations of relational databases is that it can only contain one characteristic.Eg if we use a customers accounts with a bank all their information is stored into separate row items in separate tables.Therefore a number of tables are used for various accounts, they are linked together through primary and foreign keys.One reason why relational databases will continued to be used as there is a method applying business sense and rules at the database layer.This makes sure that when a customer is using their card it is charged to the correct bank account, using primary and foreign