Understand what a database is not difficult.We are constantly confronted with its species, not even knowing it.For example, in any industry, in any institution, where people work, the equipment is used, there is a database where information recorded on regular units, ie,the composition of the staff personnel of the equipment used (inventory).Card file library collection is also a good example of the database.
definition
So, what is a database?It gathered together and specially organized information on a certain topic within a subject area.And if a few decades ago, the necessary information is recorded and saved on paper, now all the material of interest is entered into a computer and stored in the computer version.
Classification
On the content of the material database are divided into factual and documentary.Factual contain brief information about the described object.Information is provided in a particular manner and format.For example, when it comes to the library database, then in it about each book contains bibliographic information such as the year and place of publication, author, title, etc.The content of the work, the text of the books such a database will not contain.Human Resources in its database will keep personal information about employees - name, date and place of birth, grade schools received the profession, place of work, etc.
Documentary database can contain a huge amount of information raznotipovoy: is text, graphics, multimedia files.Thus, the discography of a entertainer - a sample of the documentary database.From it you can learn about the albums released singer, authors of songs and listen to the songs, watch video clips taken with them.
Thanks to modern technology the boundaries between factual and documentary databases are no longer sharp.Now we can easily connect information from one database type to another.
Information Warehouse - that's what the database and access to a huge number of them thanks to the Internet has become a very, very simple task.
By type of processing and presenting information database is divided into relational and network.
What is a relational database that can be sorted out if the issue information in the form of tables.The tables are linked.Thus, the inventory in the warehouse store toys can be presented in a table, where the columns are listed types of toys (bears, dogs, elephants, etc.), the number of each species (bears - 20 dogs - 35, etc.), the price hit a grand total value of all goods.
relational database is very easy to use and familiar for a long time.School diary timetable, records of homework, assessments and observations - a tabular database.Schedule of trains or buses at stations - as a relational database.
relational database consists of rows and columns.Table row is also called a record, and the column - field.The record contains information about a system object model, which is a table.
more complex model database is the network database.In fact, the online database - it is the Internet itself, the World Wide Web, the global network.Through hyperlinks, millions of documents are linked.So they form a single distribution network database.And almost any Internet user can connect to it and get the right information.
addition, if the number of computers connected to one master and can, thanks to him, simultaneously connected, they form a local area network or a local database.
That's what a database is and how it works.
