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You can think of a traditional database as an electronic filing system, organized by fields, records,
and files. A field is a single piece of information; a record is one complete set of fields; and a file is a
collection of records. For example, a telephone book is analogous to a file. It contains a list of
records, each of which consists of three fields: name, address, and telephone number. An alternative
concept in database design is known as Hypertext. In a Hypertext database, any object, whether it
be a piece of text, a picture, or a film, can be linked to any other object. Hypertext databases are
particularly useful for organizing large amounts of disparate information, but they are not designed
for numerical analysis. Databases offer an organized mechanism for storing, managing and
retrieving information. They do so through the use of tables. If you’re familiar with spreadsheets
like Microsoft Excel, you’re probably already accustomed to storing data in tabular form. It’s not
much of a stretch to make the leap from spreadsheets to databases. One of the most powerful
features of a database is the ability to create relationships between tables using foreign keys. For
example, you might have a Customers table and an Orders table. Each customer can be linked to an
order in your Orders table. The Orders table, in turn, might be linked to a Products table. This kind
of design comprises a relational database and simplifies your database design so that you can
organize data by category, rather than trying to put all the data into one table, or just a few tables.
A database simply holds data. To make real use of the data, you need a Database Management
System (DBMS). A DBMS is the database itself, along with all the software and functionality to
retrieve data from the database, or to insert data. A DBMS create reports, enforces database rules
and constraints, and maintains the database schema. Without a DBMS, a database is just a
collection of bits and bytes with little meaning. Database architecture may be external, internal or
conceptual. The external level specifies the way in which every end-user type comprehends the
organization of its corresponding relevant data in the database. The internal level deals with the
performance, scalability, cost and other operational matters. The conceptual level perfectly unifies
the different external views into a defined and wholly global view. It consists of every end-user
required generic data. In one view, databases can be classified according to content type:
bibliographic, full text, numeric and images. In computing, databases are sometimes classified
according to their organizational approach. There are many different kinds of databases, ranging
from the most prevalent approach, the relational database, to a distributed database, cloud
database or NoSQL database. Distributed databases can be homogeneous or heterogeneous. All the
physical locations in a homogeneous distributed database system have the same underlying
hardware and run the same operating systems and database applications. The hardware, operating
systems or database applications in a heterogeneous distributed database may be different at each
of the locations.