separation and isolation – Difficult to
access data that is available (eg. from two files – Student that achieved
good academic result and active in extra-curricular activities too.
Sharing – Data are scattered in various
files, which may have different formats. These files may be stored in
different folders may be on different computers located in different
departments. So, due to this data isolation, it is difficult to share data
among different applications.
control – File systems have no
centralized control of the data descriptions. Tables and field names may be
used in different locations to mean different things. For example, the DSW
files may list a student as having a single Name field that is made up of
students’ Initial and Last name eg S Ahmad. The Proctorial department may
keep the students’ name in three separate fields; First name, Initial, Last
Name. This may make it difficult to compare the data in the two files or at
least require additional time in programming the comparison.
dependence – File structure is defined
in the program code. It is difficult to make changes to an existing data
duplication – Entering data more than
once translates into more time and money. Additional storage space is
needed. Duplication also leads to inconsistencies. When files are duplicated
and held in a number of locations situations can arise that will cause data
to be inconsistent.
modifications made in one location may not be updated in another. For
example, student address files held by the Accounts Department may be
updated while those held by the Dean of Faculty are not updated.
Modifications made to
data files may also lead to less obvious discrepancies. For example a town
name may be spelt differently in two locations eg Askot and Askote.
data (different file formats) –
Programs are written in different languages, and so cannot easily access
each other’s files.
flexibility in organizing and querying the data
– Fixed Queries. Programs are written to
satisfy particular functions. Any new query needs a new program.
Problems – Any operation on a database
must be atomic. This means, it must happen in its entirely or not at all.
Problems – Database should be
accessible to users in limited way – each user should have access only to
data concerning his requirements. This is not easily accomplished in
file-based information systems.
Programs – Increased number of
different application programs.
data manipulation capabilities: Data in
traditional file systems is not easily related, particularly if the files
have been developed for separate purposes. If the organization requires
information to be generated that accesses data from several unrelated files
the task may prove difficult or require re-entry of data. For example, in a
library the catalogue of books may be held in one file. Books on order for
the library may be held in another file. When books are received the
catalogue will need to be manually updated if the two files are not related.
development times: Each new application
requires development of the program along with the development of the
relevant files for that application. Although the data may be held
elsewhere in the organization the data will need to be imported or
re-entered into the new files. This takes time. As organizations grow and
change they need to change their internal applications quickly to meet new
demands. Lengthy development times are a disadvantage.