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Search strings

Constructing a search string: proximity, truncation and wild cards

The power of Boolean searching can be extended further by using proximity, truncation and wild card operators in your search string.

Proximity searching

This allows you to specify that records found by your search contain one search term near another. For example, you are interested in red cars, a search string such as

red and cars

may return irrelevant records because red is a very general adjective and could describe many other things in a record. The near operator requires that a record has keywords within a set number of words from one another in the text, making it more likely that there is a meaningful link between the terms in the record. Therefore you could use the search string:

red near cars

The syntax used for proximity varies amongst search engines; eg sometimes next is used rather then near - you should check the databases' help pages to find out if and how proximity can be used. How close the keywords must be will also vary between search engines.

The near operator works best when you are searching for closely related keywords that you would expect to be used in the same sentence or paragraph, as an alternative to the and operator or a phrase if you are getting poor results. However, it should be used with care as it is easy to miss out on relevant documents.

Truncation

This allows you to search for all the variants of a word without having to specify them all in your search string. It is very useful to take into account plural and singular forms of a noun. For example,

car*

asks the search engine to search for both car and cars, or any word beginning with car such as carriage or carburettor. So, as with the not operator you have to be careful when using this operator or you may get a lot of irrelevant records. Think about how many words might start with a root such as car before using truncation. If you simply wish to include both the singular and the plural forms of a noun in your search you might be better off using the or operator:

car or cars

As for proximity, the syntax used for truncation varies amongst databases, you need to check the databases' help pages to find out if and how truncation can be used.
Click here for examples and further explanation of how truncation works.

Wildcards

This is like truncation but rather than allowing for variation at the end of a word, it allows for variation in a character in the middle of a word. Wild cards are especially useful for taking into account variations in spelling. For example, many words can be spelt with an s or a z, e.g. realise/realize. You could use the or operator to get around this, but wild cards are much neater:

reali*e

In the example above, any character can appear between the i and e. Again, syntax can vary between search engines, sometimes ? is used - check the help pages!

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