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Web databases

This document was written, and licensed for publication by MDA.

What is a Database?

A database is a structured container for information. Information held in an electronic database can be stored, manipulated and delivered through a variety of media and for a variety of purposes. This information can be interrogated, or queried according to criteria defined by the user.

A web database is held on a central computer or server and can be queried by remote users through the Internet. There are two main uses of web-based databases:

  • A database of information that is integrated into the HTML of a website and which can be queried by users via an online HTML form. Examples of this would be an online OPAC, or database of suppliers;
  • A database of information which can be combined with a set of templates to generate and display web pages dynamically based on a request made by the user. A website produced in this way is called a dynamic site and the type of database that enables this process is called a content management system or CMS.

This fact sheet will concentrate on simple online databases. For further information on selecting and implementing a content management system, refer to the fact sheet on Content Management for the Web.

How Do Online Databases Work?

Most modern database systems will be based on a relational model. A relational database is a sophisticated way of linking 'sets' of information by means of a common key. In effect, all of the different sets of information share one field in common (usually an ID or reference number), which allows them to be related to each other. An example of this would be a transactional system in which customers and their orders are linked by a common reference number.

There are a number of ways of delivering a relational database via a web interface, but almost all rely on a client/server interface. The server computer holds a version of the database that is connected to the Internet at all times. Through this connection, clients, or remote users are able to ask the database questions. The server then processes these requests and issues an answer. This process is managed by a set of standards known as Open Database Connectivity (ODBC).

Whatever the software which houses your database, it is likely that users will interact with it online using a variation on the Structured Query Language (SQL). SQL is suited to the web because it provides an efficient and flexible way of talking to relational databases without having to know how they work.

There are a range of relational database systems available, from powerful architectures such as Oracle to relatively simple free software such as MySQL. When deciding which to select, there are several factors which you should consider:

  • Installation - how complex is the software to install on your server? Do you have the skills in-house to ensure that it is installed properly?
  • Maintenance - who will look after the day-to-day running of the database? Is there anyone in-house with the technical skills required, or will you need to out-source management?
  • Cost - database systems range from free open-source software to proprietary systems that cost thousands of pounds in licenses each year. Always choose a system that is appropriate to the functionality you need, but also provides room for development in the future;
  • Licensing - database licenses can be complex, and you may be charged according to how much usage your system receives, or how many computers log on to it in a specified time period. Many suppliers now provide specific contracts for web-delivery, but these can be prohibitively expensive;
  • Hosting - will your website host allow you to add a database to the site? Some systems require specific technologies to be installed. Always check the range of database systems that your web host is prepared to support;
  • Security - most databases require the presence of a command shell, which effectively means that remote users can interact directly with the software on your server. You will need to ensure that this shell is securely separated from the rest of the software on the server to deter potential hackers;
  • Migration - if you have an existing offline database (for example a museum catalogue), which you would like to make available via the web, you will need to select a database system that makes it easy to transfer the information. An example of this is transferring information from an offline Microsoft Access database into on online MySQL system. MySQL contains special features that allow it to import information directly from Access simply and easily.

It is also important to consider whether you really need an active online database which users can query via the web. In many cases, it may be simpler to publish a series of HTML pages from your existing offline database software and link to these from your current web pages. Online databases can be expensive to implement and costly to manage so you should always ensure that they are providing genuine added value to your services.

When Should We Use an Online Database?

Online databases sit somewhere between a simple static website written in HTML and a dynamically-generated site built around a CMS. They are useful for very specific functions in which it is important to make a set of information available and searchable to users via the Internet. Specific situations in which it may be appropriate to provide an online database include:

  • A catalogue of museum objects which can be searched or browsed by users through your website;
  • A survey comprising responses to a number of questions which your users can sort or analyse according to combinations of criteria;
  • A database of products with associated information, images and prices which can be searched by your users and used as the basis for an order (for further information, see the fact sheet on e-Commerce).

The key feature of online databases is that they allow your users to define how they interact with the information you present. Always be aware of the requirements of your users when creating any database interface. For example, if you are providing pictures as part of your database, always ensure that users can view small thumbnail images before they have to download large image files, which may not be relevant to what they were looking for.

Searching and Browsing

People use online databases in a variety of ways, which fall broadly into the following categories:

  • Searching - when a user knows what they are looking for, and is trying to identify the relevant information within your database. A common way of doing this is to provide what is known as a free text search. This means that the user can type a word or phrase into a form on your website. The software will then look through the database, identifying all of the times that word or phrase appears. This information is then presented to the user as search results from which they can select the occurrence that is most relevant to what they were looking for;
  • Browsing - when a user doesn't have a specific piece of information that they are looking for, but is instead exploring the kinds of information contained within your database. To facilitate browsing, you need to provide the user with various pathways into your information. Most databases do this by suggesting searches based on, for example, subjects, themes, date ranges or geographical locations. In designing browsing systems for your database, it is vital to consult users to find out how they approach your information, and the kinds of thematic pathways which they like to use.

Search Results

Once the software has queried the database, it returns the relevant information as a set of search results, which are displayed to the user via a web page. These search results can be formatted in a number of ways to enable the user to reach the information they are looking for. These include:

  • Where possible, search results should be displayed in order of their relevance to the original query. There are various ways of doing this, but a good rule of thumb is that if the search term appears several times in a database record, it is likely to be more relevant than one which appears only once;
  • It is always a good idea to provide a summary version of search results. This usually includes a title and short description of the relevant record. If necessary, you can provide the user with the option to view all of the information in a search result at the same time, but it is much easier for them to scan the summary to find their answer;
  • It is usually a good idea to limit the number of summary search results displayed on any one page. Commonly, search results are grouped in batches of 20 or less, with the option for the user to progress through a series of screens to view consecutive results;
  • It is easy for a user to become lost when searching or browsing database records. Always ensure that your navigation allows them to return to the main search page or to browse a different theme.

Where Can I Go for Further Advice and Information?

The best way to learn more about web databases is to use them. There are many examples within the museums sector. Other resources include:

The Web Developer's Virtual Library is a complete resource of information on web development and features an excellent section on web databases and the various different types of software available.
[ www.wdvl.com]

This fact sheet was compiled with generous assistance from Nick Poole of Resource: the Council for Museums, Archives and Libraries, Nick Gander of the former Yorkshire Museums Council and the former Committee for Area Museum Councils.

MDA provides impartial resources for all aspects of collections information management. For more information please contact: Collections Link - 0845 838 4000.

November 2002