Preparing and running searches

It is when carrying out subject searches that users need to take time to prepare their search. They should consider, before carrying out a search on a source of information, whether they need to use operators, wildcards or masks, and which specific fields should be consulted. In short, the query should be translated into a documentary language and adapted to the source of information in question in order to obtain the best possible results.

Most sources of information (databases, electronic journals, library catalogues, etc.) use their own query or search software. Despite the differences there may be between them, most allow for searches of specific fields (author, title, subject, etc.), and for the focusing and adjusting of searches to meet specific needs through the combination of terms using Boolean operators (AND, OR and NOT) or truncation (with wildcards such as (*), ($) or (?)).

Boolean operators are the logical operators AND, OR, and NOT. They are used when creating search strategies and allow for inclusion, exclusion or union of search terms. By adhering to set theory, we can combine different search terms using three logical operations: conjunction (AND), disjunction (OR) and exclusion (NOT). This allows us to increase (OR) or limit (AND or NOT) the results obtained.

When we talk about shortening, we are referring to the use of symbols (*, $, ?) that we usually put at the end or in the middle of a search term. By using shortening, we are able to search via the roots of words. Shortening means that we do not have to specify the different endings for the same word, which simplifies the search strategy. When we use these symbols in the middle of a word, they are called masks and prove useful when we are searching for terms with alternative pronunciations.

Examples of searches with Boolean operators

AND: This retrieves all the documents that contain both terms; for example:
democracy and spain: this will return all the documents containing the terms "democracy" and "spain". Both terms must appear in the document.

OR: This retrieves documents which contain at least one of the search terms; for example:
democracy or spain: this will return documents with "democracy" or "spain"; i.e. this will include documents with "democracy", or "spain", or both.

NOT: This operator ensures no documents are returned with the term entered; for example:
democracy not spain: this will return all those documents containing the term "democracy" but not the term "spain".

Examples of searches with truncation

The most commonly used truncation symbols are the question mark (?), asterisk (*) and dollar sign ($).

The asterisk (*) or dollar sign ($) substitute any word ending, regardless of the number of characters this may represent. For example, if you search for "documen*", the results will include "documentation", "document", "documents", "documentary", etc.

The question mark (?) takes the place of any one single character in a given search term. It is very useful for finding terms that include the ñ, for example, when the keyboard being used does not have this character. For example, if you search for "m?cronutrients", the results will include both "macronutrients" and "micronutrients".

The truncation symbols (*) and (?) can be combined if the platform so allows. For example, if you search for "espa?ol*", the results will include "español", "española", "españoles", "españolas", etc.

Although the search interface of the different information sources that we use offers its own way of functioning and features, most systems use very similar techniques, mainly when offering the possibility of conducting what is known as an "advanced search". Knowledge of the characteristics specific to each information source and knowing how to use them is important when it comes to getting the most out of their possibilities and retrieving the most suitable information.

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