When you search a database, it is important to think about how the database will interpret your search statement. Your search can consist of single words or phrases, or you can combine terms. Single term searches are usually no problem, but if you are searching for a combination of terms, it is important to combine those terms effectively. Whether you are searching a library catalog, an article database, or Google, the same principles apply.
Here is one example of how you can use your research question to develop key terms, synonyms, and alternate terms that can be used in database search statements.
Does television violence have a negative effect on preschool age children?
television, violence, preschool children
Synonyms and alternate terms:
television - TV
preschool children - kindergarten, nursery school, toddlers
If you would like to see how each of the examples below works in a database, copy the italicized search statement and paste it into the first search box in ERIC, an important database for research on topics related to children, education, and learning.
Example 1: Using AND to connect key terms
In the example above, you want to find only that information which includes television and violence and preschool children. If there is information on television and violence which doesn't include preschool children, you probably don't want it. Use AND to focus your search on only the information which includes all your concepts.
Example 2: Using OR to connect synonyms and alternate terms
In the example above, each of the terms represents the same concept: preschool children, so you want to find items that contain one or more of those terms. Some items will have preschool children, some kindergarten, some nursery school, some toddlers. Some items may have 2 or more of your terms.
You may also want to use TV as an alternate term for television. Your search would look like this: television or TV. Use OR to search for items that contain any alternate terms for a key concept.
Example 3: Using both AND and OR in the same search statement
Notice, in the example above, that parentheses are used to group alternate terms used to represent the same concept. Whenever you use both AND and OR in the same search statement, use parentheses to group multiple terms that represent the same or similar concepts. Otherwise, the database will not be able to interpret your search statement correctly.
Quiz: In the search statement above, what term will be found in every item that the search retrieves?
Example 4: Searching for alternate terms with the same base word.
What if you want to find all the variations on the word child: child, children, child's, childish, childhood, etc? You could use OR between each possibility. But you might forget something, such as children's. Most databases allow you to use a shorthand version of OR when the base word is the same. It's called "truncation." In most databases the symbol is the asterisk (*).
You can also use truncation when you want to be sure to get plural and possessive forms of your search terms.
Example 5: Putting it all together
When you need to, you can use AND, OR, parentheses, and truncation to create very complex search statements.
♦ Use AND to connect key concepts. When you connect search terms with AND, your search retrieves only those records in which all terms are present.
♦ Use OR to connect synonyms and alternative terms. When you connect search terms with OR, your search retrieves all records containing at least one of the terms.
♦ When you use both AND and OR in the same search statement, put parentheses around the terms connected using OR.
The search logic you use when you search databases (when you use and, or, and not to combine terms) is called Boolean logic. Here is a tutorial that you may find helpful in better understanding how to use Boolean logic when you search.