Search strings

Constructing a search string: putting it all together

Using Boolean operators it is possible to construct complex strings of search terms. To ensure the search engine does exactly what you want it to, you need to use brackets (parentheses) to make the structure of your search string clear.

Let us continue with our example from the previous pages. We have decided that it would be best to use "car or cars" rather than to use truncation (car*). We also want to specify that the word red occurs near car or cars. You could use the search string:

red near car or cars

There is a danger that the database will return records that contain the terms red and car near one another, or contain the term cars - the link between red and cars we want might be lost. Parenthesis, also known as nesting, avoids this. The operation specified within a set of brackets is completed before the rest of the search. Returning to our example, to make sure the database does exactly what we want, you would use the string:

(red near car) or (red near cars)

Whilst parenthesis is a powerful tool you have to take care in the order of terms in search strings. Lets say we are interested in red cars or red automobiles. You might construct the search string:

automobile and (red or car)

Unfortunately this will contain records containing the terms automobile and red, or the terms automobile and car, which is not quite what we want. The correct search string would be:

red and (automobile or car)

An incorrect search string is quite obvious when combining an adjective with nouns but with combinations purely of nouns you have to be more careful.

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