Databases also allow you to set up rules that ensure that data remains consistent
when you add, update, or delete data. Imagine that your imaginary car sales company
has two salespeople named e.g. John Smith. You can set up a database to ensure that
each salesperson has a unique ID, called a unique identifier (so that the John
don’t get mixed up); otherwise, telling who sold which cars would prove impossible.
Other data storage systems, such as text files or spreadsheets, don’t have these
sorts of checks and quite happily allow you to store erroneous data. For example,
you might specify that an employee’s social security number must be unique in the
database. Or if a car is sold and it’s listed as being sold by the employee with
an ID of 1234, you might add a check to see that full details of employee 1234 are
held in one of the database tables.
Databases also make sharing data between different systems much easier than using
proprietary data formats—that is, a format specific to a particular program, manufacturer,
or operating system. An Excel spreadsheet, for example, is easily read on a Windows
machine with MS Office, but it is more of a challenge to read on a UNIX, Macintosh,
or Linux machine because those computers handle data in a different way. Even on
a Windows machine, you need to have MS Office installed. You can house a database
on a central computer, put the database management system on there, and then enable
access via a local network or the Internet.
Databases are used pretty much everywhere. Data processing played a big part in the development of computers, and even today it is one of their main roles. Nearly every walk of life or business requires a database somewhere along the way. Databases are commonly used on personal computers to store data used locally, and on company networks databases store and share company-wide information.
However, Databases are great at dealing with large amounts of data that need to be searched, sorted, or regularly updated. Databases combined with SQL allow you to get the answers you want in the order you want.