Archive for the ‘Database’ Category
If you work on the internet, have spent a vast amount of time stumbling or surfing its pages or have seen Microsoft’s television commercials recently, you probably have heard of The Cloud. From their witty, silly and memorable commercials about being bored in an airport, copying and pasting imperfect photos together for the perfect family photo, and sharing special and comical childhood moments with family and friends.
But What is The Cloud?
The cloud is actually just a little nickname or aggregation for cloud computing. Cloud computing is something that people are using daily if they are using the internet or a database for work or for pleasure. Cloud computing is actually the resources required by a computer network, such as databases, applications, e-mails, and files, that are accessed by a consumer or customer from a separate location such as a home or business.
Oftentimes there is no software or data requirements for the consumer or customer in order to obtain the information from the cloud, requirements might include a web browser or a minimal operating system. Plus, cloud computing reduces the cost of maintenance and resources for customers and consumers because they are using a shared resource from a distance and therefore do not have to deal with hardware, software or technical issues; thus freeing the customer and consumer from mundane hassles that might prevent workflow or internet surfing capacities.
The image diagram below, from Wikipedia, might help with understanding what cloud computing really means. As you can see from the image, there are various computers that are connecting to The Cloud at one time and they are all able to share information and obtain information simultaneously.
Database Management System (DBMS) :
Database Management System is the collection of programs and tools that enables users to create and maintain the database.
A DBMS is also a general purpose software system that facilitates the process of defining, constructing and manipulating databases for various applications.
Characteristics of Database Management System :
(1) Self Describing
(2) Insulation from Programs and Data Abstraction
(3) Support of Multiple views to Database.
[4] Advantages of DBMS:
1- Controlling Redundancy :
There are provisions in all database models that redundant storage of the data can be avoided.
2- Security Over Unauthorized Access :
This is the feature found in the database that without proper login, no one can modify or store database. The security can not be achieved with the flat file (Sequential) approach.
3- Providing Persistent Storage for Database Objects :
Database can be used as the persistent storage of Program objects, Database and Database structures. This meant that a complex object of programming languages can be stored in the database. This gives more flexibility and compatibility of database over the programming languages.
4- Permitting Inferencing and Actions using Rules :
Inferencing is the method for defining deducing rules for inferencing new information from stored database. Such database are called as Deducible Database. In other words, there must be some methods to provide information by logical implementation on the stored database.
6- Allowing Multiple User Interface :
DBMS has the capability to provide concurrent execution of various parts of the database. In this approach, Deadlock and other anomalies are also handled by the DBMS.
5- Backup and Recovery :
Database Management Systems have proper mechanism to Backup the whole database and recover when any disaster comes to picture. There are methods for Disaster Recovery in all DBMS.
[5] Data Models :
A data model is the set of conceptual tools for describing data, their relation, semantics and consistency constraints. There are following data models-
(1) Hierarchical Model
(2) Network Model
(3) Relational Model
(4) Object Relational Model
Describing all of these would be out of context. You should know that with all these, Relational Model is famous one. Newer implementation of DBMS do follow Object Oriented Model. Such as Oracle, Sybase and SQL Server.
[6] Logical and Physical Data Independence :
Data Independence is the quality of DBMS that ensure the capability to change the database in a manner that the change in one level does not affect the other level. Such as change in the physical storage (Internal Level) does not affect the database structure (Conceptual Level).
(1) Logical Data Independence:
Capability to change the Logical structure without changing the external and internal schema of the database.
(2) Physical Data Independence:
Capability to change the Physical schema without any change in the conceptual schema of the database.
[7] Database Languages :
There are following database languages-
[1] DDL (Data Definition Language)
[2] DML (Data Manipulation Language)
[3] DCL (Data Control Language)
[1] DDL (Data Manipulation Language)
This is the language concerned with the creation of database structure and schema related with this. This language is concerned with the definition of the whole database architecture.
DDL is used to define and manage all the objects in an database. Such as creating Databases, creating security objects that define the whole database.
[2] DML (Data Manipulation Language)
Insertion, Update , Delete and Selection are the activities concerned with the database manipulation language.
DML is used to Select, Insert, Update, and Delete data in the objects defined using DDL.
[3] DCL (Database Control Language)
Database control language is concerned with the consistency maintaining, authorizing access and other control over the database.
There are some other languages which must be known. These are -
VDL (View Definition Language) : Providing means to view the conceptual schema of database for external level of three level schema.
SDL (Storage Definition Language) : Providing means to change or modify the internal schema of the database.
[8] Relational Database :
The Relation database model is based upon the conception of implementing the database with the Mathematical Set Theory. In this model, data is collection of tables called Relation in the set theory. The Tabular representation of data contains rows and columns in which rows represent set of attributes of individual entity and the columns represent the attribute of entity.
A model is also said as Relational Database Model, if it follows complete set of Rules defined by Dr. E.F. Codd. There are 12 Rules of Dr. Codd. In all of them, only Oracle is supposed to follow nearly all of them. But, the best in performance is Sybase which is more easier to configure that of Oracle.
SQL :
SQL is actually Structured Query Language. This is pronunciated as ‘sequel’, but ‘Ess-Que-El’ is also correct.
It was initially named by Dr. E.F. Codd who named it Structured English Query
Language (S E Que L ) as Sequel.
SQL is based on the Relational Model. Nearly all the database implementation in the world are in Relational Model. Sybase ,SQL Server, Oracle,
DB2 are the famous implementation of Relational Model. But these are also kept in the Category of Object Relational Model.
Microsoft Access is not supposed to be relational model. This actually uses some
flavors of relational database. But, can not be taken into account of pure
Relational database.
ANSI-SQL :
American National Standards Institute handles the standards of SQL. The changes
are made time to time. We have ANSI-SQL-89, ANSI-SQL-92 and other standards.
There are several levels decided. Microsoft SQL Server is given entry level.
Conclusion :
This is all about providing protection for passwords. There are many other
things to research in the same scenario and I would like to share my ideas when
such studies are complete. Overall, my aim was to open your eyes that backups
are not only to secure your data, but due to carelessness this may lead to
leakage of information. In my opinion, disclosure of important information is
more serious matter than loss of information. So, awareness is important and
there is a little effort to apply in securing your backups.
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