Database management systems (DBMS)

A database management system (DBMS) is a computer program, or collection of computer programs used to collect, maintain and analyse the large volumes of data contained within vast databases such as those found among the server stacks of large multinational corporations. DBMS can seem baffling at first sight, so the guide below is designed to provide you with all the information you need to make sense of the technical terms used within the field.

How does a DBMS organise data?

DBMS may make use of one of four types of organisational structure: hierarchical, object-orientated, network or relational. It is important to understand the differences between each of these, since the organisational structure of the DBMS will influence its speed of operation.

The four types are described below:

Hierarchical databases are those which are organised as the branches of a tree, with the root directory at the top, followed by parent and child directories of various classifications. These databases are incredibly easy to update since the directory trees are already defined and additions can be made by simply adding branches.

Object-orientated databases are designed to handle objects rather than discrete columns of data sorted into fields. The object-orientated database is a powerful way to organise multimedia files, but is also more expensive to implement, and requires more work to maintain and catalogue data.

Network databases are quite similar to hierarchical databases, except that each child (referred to as a member) can have more than one parent (referred to as an owner), thereby allowing the database to appear as more of a network or web of related data rather than a tree.

Relational databases allow users to access data using a common field, such as a username, identification number or product code, rather than passing through a hierarchy to access the required information. Searching the databases - what is a query?

Queries are searches of the database made through the use of a query language. Query language is a simple type of programming language designed to allow direct interaction with the database by means of simple words such as 'delete', 'modify' or 'select'. By making use of queries, the database can be accessed or modified quickly and easily without the need for third party applications. Structured Query Language (SQL) is one of the most commonly used query languages, so familiarity with SQL is advised before beginning any high-level database operations.

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Displaying information from the DMBS

While using a query language allows the user to interact intimately with the raw data found within the database itself, a database access application may be designed to allow users with a limited knowledge of query language to perform common tasks and searches without diving into the nuts and bolts of database computing. Applications provide the advantage of a graphical user interface (GUI) designed specifically for the needs of the user, and allow less experienced users to search the database with ease. Despite this, applications sometimes remove some of the raw functionality that can be achieved through the use of a query language, so it is often wise to include a query console for direct input of query terms for the more experienced users.

Advantages of a DBMS

The main benefit of a well-designed DBMS is its ability to bridge the gap between the database itself and users of differing skill levels. Opening up the database to all of your workers is a great way to boost productivity and efficiency, while still keeping tight controls on the data your system is able to store. Although access to a database is generally in the form of an 'all or nothing' event, passwords can be installed in order to facilitate the access of only certain users to the database, thereby maximising the security of your records.

Disadvantages of a DBMS

The main disadvantage of a DBMS is its cost; these systems are hugely expensive for a large company which requires a license to facilitate use of the program on a large number of computers. Despite this, the majority of users will attest that the ease and speed of database searches and maintenance that these systems are able to provide vastly outweighs any cost incurred during installation. One additional problem associated with a DBMS is its security. Since access to the database is 'all or nothing', if someone is able to gain unauthorised access to any part of the database, they will have free roam of the entirety of its contents. For this reason, powerful security features must be put in place to prevent unauthorised users from making use of the database without the appropriate permissions, and sensitive documentation should perhaps be stored on a separate database or in encrypted, password protected files.