Types of Database Users - DBMS

                         Different Types of database users

A main objective of a database system is to provide a domain for regain information from the databases and storing new information into the database by the users. Basically    database have mainly four types of different database users that use it according to their needs, sorting by the behavior that they are suppose to interact with the organization.

                                     Application programmers:

These are the experts who interface with the organization through the use of DML (Data manipulation Language) calls, that are coded in a program written in a host language (for example, COBOL, PL/S, Pascal, C). These languages are the basically mentions to as application programs

E.g.: Government, banks, Business professionals, website owners, Mails, and Companies. These all uses applications that Transfers data, useful information and money.

                                   Sophisticated Users: 

These are the users who use these systems directly. They are not programmers and they don’t have knowledge of programs basically. These entire queries are submitted to a system who converts it into useful information. These users send request in database query to retrieve the information they needed to implement

                                      Specialized Users:

 These are those who are specialized in professional database applications like animated and graphics databases. They are used for banking, accounts and in personal computers.

E.g.: modern system like mobiles, tabs, laptops that uses graphic design in video and audio.

                                             Naive users: 

these are the common peoples or persons that use database applications for their personal and business uses. These applications make a work easy for owners, managers and workers.

For example: When a person buys something and pay a bill via credit cards then a data is updated in account. That’s how it works.

A user updates database over time to time and the information is deleted and inserted according to needs. The overall information that is stored in database at a particular time is known as instance of the database. The layout and template design is called the database schema.

Database administrator - schema definition and functions

It is one of the important and the main reason for containing database management system (DBMS) is to have take control of the both data and programs that accessing

That database administrator (DBA).the DBA administers and the three levels of the database (The three level architects) and in discussion with the overall

The user group sets up the alternative of the global view or conceptual level of the database.

Here below are the discussions about the functions of the Database administrator:

Schema definition:

The development of the real database schema is achieved by writing a set of definitions, which are converted by Data definition language (ddi) complier to a set of tags that are stored in the data dictionary for permanently.

Storage method and access method definition:

The development of the suitable storage shape and entrance method this is achieved by compositions a set of definition, which are converted by the data storage and definition language compiler

Schema and physical organization modification:

One of the changes in the database schema or the description of the physical storage organization.

These are some changes that are very rare and unique and are achieved by compositions a set of alternative which are used by one of the data definition languages complier or the data storage and ddl complier to produce changes to the suitable internal system tables like data dictionaries.

Granting of authorization for data access:

It grants data access to the various types of database user by the different types of authorization to it and are useful in data administration system

Integrity constraint specification:

These limitations are kept in a very important system  formation that is seek by the database manager whenever it comes to one of the expensive tools that the DBA uses to transport out data administration in data dictionary 

three level architecture of dbms

Architecture of DBMS

A database managements system is composed of many interrelated components. These components are organized so that they work in tandem and achieve the goal of the system is referred. These systems are also designed in different types of architecture. A DBMS system that provides three levels of data is three level architects that are external, conceptual and internal levels.

External Level or Sub-schema

The external level is at the top level of database system and it is very first level of architect .this level basically are the users who use database .each view of this level is represent by the means of schema known as external schema or sub-schema. It consists logical records and relationship‘s definition in the external view.  The external schema consists of methods that derived objects from the conceptual view to the external view. The object includes entities, attributes, and relationship.

Conceptual Level or Conceptual schema

Conceptual level is second and middle level of architect. The whole database is represented by the single conceptual view and all of the database entities and the relationships among them are included in the conceptual level. All of the records and relational ship included in conceptual view are described by it in the database. The schema of this level defines the conceptual view therefore there is only single schema per database. The conceptual schema consists of methods that derived objects from the internal view to the conceptual view.

Internal level or physical schema

Internal level is third and the last level of architect. This is closest to physical storage memory in database. The database uses the access methods and data structure that are described by the internal view. The means of stored records and the method in which data fields are represented are defined in it.

Mapping between three levels

There are only two types of mapping that are needed in the database associated with different levels. Mapping between first and second level defines and provide inter-exchange of records and relationship among the external and conceptual levels.

                           The mapping between conceptual   level and internal level is done in second phase. There are possibilities that the internal records are divided into two or more physical records. These records are stored on secondary devices that are used for storage.

All of the mappings are supplied by data base managements systems