Datasheet

SQL and Relational Database Management Systems 1
Scientific database
A database for genome research and related research in molecular and cellular biology can be a
good example of a scientific database. It contains gene catalogs for completely sequenced
genomes and some partial genomes, genome maps and organism information, and data about
sequence similarities among all known genes in all organisms in the database. It also contains
information on molecular interaction networks in the cell and chemical compounds and
reactions.
This database has just one user group — all researchers have the same access to all the informa-
tion. This is an example of a data warehouse.
Nonprofit organization database
A database of an antique automobile club can be pretty simple. Also, such an organization would
not typically have too many members, so the database is not going to be very large. You need to
store members’ personal information such as addresses, phone numbers, areas of interest, and so
on. The database might also contain the information about the automobiles (brand, year, color,
condition, and so on). The automobiles are linked to their owners (members of the club). Each
member can have one or more vehicle, and a vehicle can be owned by just one member.
The database would only have a few users — possibly, the chairman of the club, an assistant,
and a secretary.
The last two examples are not business-critical databases and don’t have to be implemented on
expensive enterprise software. The data still has to be kept secure and should not be lost, but
in case of, let’s say, hardware failure, it probably can wait a day or two before the database is
restored from a backup. So, the use of a free database, such as MySQL, PostgreSQL, or even
nonrelational Posgres is appropriate. Another good choice might be Microsoft Access, which is
part of Microsoft Office Tools (Professional Edition or better). Microsoft Access works well with
up to 15 users.
Database Legacy
Flat file, hierarchy, and network databases are usually referred to as legacy databases. They rep-
resent the ways people used to organize information in prehistoric times — about 40 years ago.
Flat file databases
The flat file database was probably one of the earliest database management systems. The
idea behind flat file is a very simple one: one single, mostly unstructured data file. It mirrors
‘‘ancient’’ pre-computer data storage systems: notebooks, grocery lists, and so on. You could
compare it to a desk drawer that holds virtually everything — such as bill stubs, letters, and
small change. While requiring very little effort to put information in, such a ‘‘design’’ becomes
a nightmare to get the information out, as you would have to scroll through each and every
record searching for the right one. Putting relevant data into separate files and even organizing
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