Database is a revolution from flat-file format. For flat-file, all the data were stored with
each record in one large table. For example, if one wanted to place an order,
the data was recorded by detailed information such as customer’s name, address,
phone number and SSN. This requirement was performed every time when the same
one wanted to do the same thing. And the information was written down
repeatedly into large files. Thus the problem appeared. Not only the large
space was needed to restore the big amount of information (can be either in
paper or in computer memeroy), the human sources to maintain these data were
also a large pool.
So on 1970, Dr. Edgar Codd first defined the relational
database. The biggest advantage of this database was reorganized data in the
form of relations to eliminate the redundant data. In other word, the database
method doesn’t care the order of columns and rows. It doesn’t equal to the
table although every relationship can be depicted as a table. For example, the
two different tables below represent the same relation. The computer only needs
to memory the relationship between column and rows to generate several tables. In
terms of how to generate these relations, terms of tuples and attribute are
generated. In relational database theory, a relation is a set of tuples that
belong to a data domain. And each distinct domain used in the definition of a
relation is called an attribute. For example, the Name, studentid and courseid are
three attributes. They belong to different domains.
The method is operated by the software called relational
database management system(RDBMS). Generally, the RDBMS responds to command. The
command is input which is written in the database language such as SQL and the
responds are output which include completion codes, messages and results of
queries.
The benefit of reducing saving storage space is not a big
problem due to the technical development. However, the relational database
should be still be used because it can reduce the entry errors as Gayaneh said
in her blog. Because each item is stored only once, so once you can
find the specific error you made, you can correct a series mistake.
Sources: http://www.techrepublic.com/article/relational-databases-the-inspiration-behind-the-theory/5034633
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