DialogWeb Help: Logical and Proximity Operators

Logical Operators

Logical operators (and, or, and not) are used with the SELECT command to establish a relationship between two or more search terms.

• OR
  OR logic groups search terms into a single set and specifies that at least one of the terms must be present in each record retrieved. For example, to retrieve records that contain the term moon or the term lunar, enter s moon or lunar. The system response to this command is a display of the number of records that contain the term moon, the number of records that contain the term lunar, and a set of records that contain either the term moon or lunar.
• AND
  AND logic groups search terms into a single set and specifies that all terms must be present in each of the retrieved records. For example, to retrieve records that contain the term moon and the term lunar, enter s moon and lunar. The system response to this command is a display of the number of records that contain the term moon, the number of records that contain the term lunar, and a set of records that contain both the terms moon and lunar. AND sets are smaller than OR sets because both terms must be present.
• NOT
  NOT logic eliminates terms from a search. For example, to retrieve records about eclipses but not solar eclipses, enter s eclipse? not solar. The system response to this command is a display of the number of records that contain the terms eclipse and eclipses, the number of records that contain the term solar, and a set of records that contain the terms eclipse or eclipses but not the term solar. NOT can be used with a proximity operator, for example, s economic(not w)recovery.

Proximity Operators
Proximity operators are used with the SELECT command to specify the relative nearness or adjacency of search terms.

• (W)
  The (W) operator specifies that terms be adjacent to each other and in the order specified, for example, s solar(w)energy. The (W) operator can also be used to retrieve identical terms, for example, s johnson(w)johnson.
• (nW)
  The (nW) operator specifies that terms be within a specified number (n) of words of each other and in the specified order, for example, s solar(3w)energy.
• (N)
  The (N) operator specifies that terms be adjacent to each other but in any order, for example, s solar(n)energy. The (N) operator can also be used to retrieve identical terms, for example, s johnson(n)johnson.
• (nN)
  The (nN) operator specifies that terms appear within a specified number (n) of words of each other but in any order. For example, s a(2n)b(5n)c retrieves records in which terms a, b, and c appear within 10 words of each other (3 terms and 7 intervening words equals a 10-word window).
• (L)
  The (L) operator specifies that terms be in the same descriptor unit (heading-subheading entries) as defined by the database. For example, use s solar(l)energy to retrieve solar-energy.
• (S)
  The (S) operator specifies that terms be in the same subfield unit as defined by the database.The (S) operator is especially useful for searching terms that appear in the same paragraph of the text field, for example, s library?(s)automat?.