DATABASE
DATABASE
Are a set of data
within the same context and systematically stored for later use.
HISTORY
The databases were evolving of the following form:
The files were the most common system of storage of information. To share the information between several machines.
The files were the most common system of storage of information. To share the information between several machines.
Files sequential: allowed to have a rapid access to the information,
but only of sequential form.
Files indexed: The Access
could already be random.
Later to avoid system failures appeared RAID file systems (redundant set of independent disks).
Later to avoid system failures appeared RAID file systems (redundant set of independent disks).
With the passage of
time, programs and data were more difficult, large and promise: number of
conditions, data volumes and to enable complex operations. Additionally each
user that needed access data should have protected works.
The databases hierarchical: The accesses to the information were unidirectional,
and more complicated to do the inverse way, which was needing of a time of
major calculation. (For example, it was easy to know count it had a client, but
not so easily to know of what client it was a certain account).
Relational databases: (absolute freedom of relations between tables), they
brought two very important things: the properties ACID (atomicity, consistency,
isolation, permanence) and a standard language of access to the information
(SQL, language of consultation structured).
Features of management system database
- Interacting with the Operating System
-Maintaining the
integrity
-Maintaining security
-Concurrency control-Provide mechanisms
that facilitate interaction with the database
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