The boolean full-text search capability supports the following operators:
A leading plus sign indicates that this word must be present in each row that is returned.
A leading minus sign indicates that this word must not be present in any of the rows that are returned.
- operator acts only to exclude
rows that are otherwise matched by other search terms. Thus,
a boolean-mode search that contains only terms preceded by
- returns an empty result. It does not
return “all rows except those containing any of the
By default (when neither
- is specified) the word is optional, but
the rows that contain it are rated higher.
These two operators are used to change a word's contribution
to the relevance value that is assigned to a row. The
> operator increases the contribution
< operator decreases it. See
the example following this list.
Parentheses group words into subexpressions. Parenthesized groups can be nested.
A leading tilde acts as a negation operator, causing the
word's contribution to the row's relevance to be negative.
This is useful for marking “noise” words. A row
containing such a word is rated lower than others, but is
not excluded altogether, as it would be with the
The asterisk serves as the truncation (or wildcard)
operator. Unlike the other operators, it should be
appended to the word to be affected.
Words match if they begin with the word preceding the
A phrase that is enclosed within double quote
"’) characters matches only
rows that contain the phrase literally, as it was
typed. The full-text engine splits the phrase
into words, performs a search in the
FULLTEXT index for the words. The engine
then performs a substring search for the phrase in the
records that are found, so the match must include non-word
characters in the phrase. For example,
network" does not match
If the phrase contains no words that are in the index, the result is empty. For example, if all words are either stopwords or shorter than the minimum length of indexed words, the result is empty.
The following examples demonstrate some search strings that use boolean full-text operators:
Find rows that contain at least one of the two words.
Find rows that contain both words.
Find rows that contain the word “gene”, but rank rows higher if they also contain “protein”.
Find rows that contain the word “gene” but not “protein”.
Find rows that contain the word “gene”, but if
the row also contains the word “protein”,
rate it lower than if row does not. This is
“softer” than a search for
-protein', for which the presence of
“protein” causes the row not to be returned
'+gene +(>circuit <network)'
Find rows that contain the words “gene” and “circuit”, or “gene” and “network” (in any order), but rank “gene circuit” higher than “gene network”.
Find rows that contain words such as “gene”, “genes”, “genetic”.
Find rows that contain the exact phrase “some
words” (for example, rows that contain “some
words of wisdom” but not “some noise
words”). Note that the
"’ characters that enclose
the phrase are operator characters that delimit the phrase.
They are not the quotes that enclose the search string