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. The - 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 excluded terms."
By default (when neither + nor - 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 and the < operator decreases it.
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 - operator.
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 * operator.
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 and performs a search in the FULLTEXT index for the words. Nonword characters need not be matched exactly: Phrase searching requires only that matches contain exactly the same words as the phrase and in the same order. For example, "test phrase" matches "test, phrase".