The structure of a file is based on small units which from that unit in the ascending order takes the form of a file. The description of these small units are as follows-
We know that the base of gathering information in a computer is 0 or 1. This 0 or 1 is called bit which is an abbreviated form of Binary Digit and a group of 4 bits is called nibble and a group of 8 bits is called byte. One letter of the text we put on the screen through input device, is called byte. It means byte is supposed to be the smallest unit of a file.
Data element is known as database management system or in the common language of computer we call it field.
The combination formed by the data elements related to some specific object is called record.
A file is constituted of the groups of similar records. It means, a file can be described as a group of similar sorts of records.
The size of the file has a limit which depends upon the available space in the storage medium used by you.
Database is called a group of related files. Its object is to fulfil the needs of different applications by checking the repeatition of similar data.
The main objectives of database design are speeding the response time, making more information available on reduced cost, controlling the repeatitions, making the use clearer and easier, freedom of data and program, accuracy and integrity of the system, speedy recovery, secrecy and safety of information and making safe and strong end. user language available.
Database management system supports the software features. It is also called fourth generation language. This computer information system is said to be user friendly.
Query language helps the user access data and without writing the computer program provides swift responses to the user's query.
There are three principal methods of organising a file which include Direct Access, Sequential and Index Sequential.
In direct access, data can be obtained in any order. No matter what the order of entering the data is, we through direct access can obtain them in any sequence,
In sequential access the data present in the file are obtained in the same order they had been stored.
The Index Sequential Access is a compromising method between direct and sequential methods. In it, the data are arranged in an order but where the data are stored, there is an index.
Generally, when the data are entered then despite observing carefulness one data gets entered more than once. Because of it the space in the storage medium goes in vain. Database helps identify this event which takes place during data entry.
The data is the most potent weapon of a company and in the case of its leakage the goodwill of the company might be spoiled and the transaction might be affected.
Data model is a framework or a mental image of the user's view.
Data file is the space where the real files are stored. Storage sequence is determined from the data model.
The logical view of data is this that how it looks and the physical view of data means how the data is stored and retrieved.
Schema is the view which helps the database management system act on the data requested by the application program in whichever storage it is. The example of schema is the display of landing and take-off of the aeroplane on the airport.
There are three types of relationship amidst data that include One to One relation-ship, One to Many relationship Many to Many relationship.
In one to one relationship, there is an association of two separate entities.
In one to many relationship any one entity might relate to several entities.
Many to Many relationship is the association of many entities with many entities
Data structures are mainly of three types hierarchical , network and relational.
Hierarchical structure is also called tree structure. In such structures, there are not more than one entities on one side
Hierarchical models are not fit for all types of applications. For example, if there is the association of many and many entities, the hierarchical structure will not work.
Entity is related to the interest of the user on the basis of which the data are collected and stored. It is also called data aggregate, for it contains several data elements.
Data entities can be explained using many terms, such as with the value key of attribute of entity and its example. For example, a student, who is an entity is known from his attributes, such as his roll no., name, class, section etc.
Normalization is a technique that simplifies the relations amidst data elements. With the help of the normalization method the data collection in the record structure is replaced with more simple records which due to being pre-informative and practical, are easily operational. In the first step of normalization the data are changed in table or relations.
Comments
Post a Comment