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LOCATION: HOME PAGE: SEARCH TIPS Using Boolean OperatorThis Page
What's a Boolean OperatorA Boolean operator is a computer-programming term for conjunctions like, AND, OR, and NOT which can be used to construct more complex search conditions for a database. They are named after the 19th century mathemetician George Boole who developed Boolean algebra, usually seen in elementary logic classes. Many database applications refer to "Boolean Search" or "Boolean operators" on an advanced search screen, so the term is worth knowing. The rest of this page will discuss the common operators and explain who they interact with databases in more detail. The AND OperatorThe AND operator is similar to using a set multiple keywords in that you are looking for items which fit both a first criterion and a second criterion.Why not just use multiple keywords then? Some databases have search forms which do not support multiple keywords, but require you to insert an "AND" between each item. How can the AND operator be visualized? One way is to image that the search criteria are two circle - each which contain records for a certain criterion. The records an AND search retrieves are those which within both the circle for the first criterion and within the circle for the second criterion. In other words, the results would come from where the criteria intersect. In the diagram below, an AND search for "rap music" and "Spanish" (i.e. Spanish
rap music) is represented visually with a yellow circle for XX and a blue
circle
for XX.
The green
circle where
the
yellow
and blue
circles cross represent those items which are XX and XX.
Venn Diagram for AND - Search Results are in green File Maker ProTo do an AND Find, select or fill in items from multiple fields. To do an AND search in the same field, enter multiple keywords. AccessTo do an AND search from a form, enter Filter mode and place keywords in multiple fields. To do an "AND" search in the same field, place search terms in quotes and put "AND" in between them. To do an AND search query, make sure to include "AND" in the query design. Google and other online search engine support Boolean searches in the "Advanced Search" options.To do an "AND" search:
The OR OperatorThe OR operator selects records which fulfil the first criterion or the second criterion. Within the same set of data, the OR search will retrieve more records than the parallel AND search would. One reason you might want to use an OR operator is to search across synonyms (e.g. "Britain" or "United Kingdom"). An OR search might also be used to pull items with related concepts, like similar genres or similar time periods in history. If you were to visualize an OR search, the circles for both search criteria would
be colored the same because results could come from either circle (or even
from the intersection where both are true). Here's a diagram representing
a search for "meregue" or "salsa" (both styles of Latino music). Both circles
are green because search results could be merengue only, salsa only or both
merengue and salsa.
Venn Diagram for OR - Search Results are in green File Maker ProFor an "OR" Find, do the following:
Access To do an "OR" search in the same field, enter Filter mode and place search terms in quotes and put "OR" in between them. To do an OR search query, make sure to include "OR" in the query design. Google and other online search engine support Boolean searches in the "Advanced Search" options.To do an "OR" search:
Exclusive OR (XOR)Some database systems may recognize an "exclusive or (X OR)" operator. This differs from the normal OR operator in that the search looks for items which fulifill just one of the criteria but not both. To return to the "salsa" and "merengue" search, the statement salsa XOR merengue would exclude items which were both about salsa and merengue. If you were trying to isolate multiple criteria, you might want to use an exclusive or search. The XOR Venn diagram shows the two criteria circles again, but leaves the intersecting area white because those results are exculded.
Venn Diagram for XOR - Search Results are in green. Excluded results are in white. The NOT OperatorThe NOT operator is used to exclude items which meet a criteria (or find items which do not meet the given criteria). This operator is helpful for searches in which you want most records, but want to throw out a specific subset of them. This is also sometimes called an inverse search. In the example below, the search is looking for items which are related to rap music for any language except English or NOT English. This is represented by a green circle containing rap music for all languages, with a white oval in the center for the English language records which have been excluded.
Venn Diagram for NOT - Search Results are in green. Excluded results are in white.
The advantage to a NOT search is that sometimes it is easier to specify the criteria to be discarded rather than the criteria to be included. If you tried to specify that you wanted non-English rap music without the NOT operator, you would have to use a very long series of OR statements such as Spanish OR French OR Japanese OR Portuguese OR.... Note: A NOT search is also called an inverse search because you are inverting the search criteria. File Maker ProFor an "NOT" Find, do the following:
AccessTo do an "NOT" search in the same field, enter Filter mode and place search terms in quotes and put "NOT" in front of it. To do an NOT search query, make sure to include "NOT" in the query design. You can also use "<>" as an alternative to NOT. Google and other online search engine support Boolean searches in the "Advanced Search" options.To do an "NOT" search:
Combining Boolean OperatorsMany database applications allow you to use more than one Boolean operator within a single search string. If you have many keywords, you can include them all with multiple "AND" statements (e.g. Rap music AND Spanish AND Los Angeles for "Spanish rap music from Los Angeles"). Similarly, you can combine OR statements as in rumba OR salsa OR merengue. One of the more interesting options is to combine a NOT operator with either the AND or the OR operator. For instances, if you wanted to find "non-English Los Angeles rap music", you could specify rap music AND Los Angeles AND NOT English. FileMakerPro Tip: Use the Omit button and Add Request options to create complex searches. For the rap music AND Los Angeles AND NOT English search, you would do the following:
Access Tip: In theory, you can place som eBoolean statements in a parentheses such as in a statement Rap AND Spanish AND NOT (New York OR Los Angeles) for "Spanish rap outside New York or Los Angeles." However Access sometimes has difficulties evaluating Boolean statements in parentheses. You may have to re-write the logic to remove or readjust the parentheses. For instance: Rap And Spanish AND NOT New York AND NOT Los Angeles. Go to Google and click Advanced Search (right of search box) then enter. keywords in boxes for each of the search types. Quick ReviewRoll your mouse over the blue box after each question to see the answer. How would you express these search problems in Boolean terms?Only records about Monet and his use of color. Records about Central America or South America. Students from all states except Pennsylvania. And these more complex searches?Graduate students from all countiries except the United States. Records about color for Monet and Manet. Next: Null Searches
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