Logical Operators

Logical operators such as AND or OR allow you to limit your search criteria in a number of ways. Table 4-2 describes some of these operators.

Table 4-2 Logical Operators

Operator Symbol Description Example Expression

AND

&

Use the AND operator to search for documents that contain at least one occurrence of each of the query terms.

Score returned is the minimum of the operands.

 
'cats AND dogs'
'cats & dogs'

OR

|

Use the OR operator to search for documents that contain at least one occurrence of any of the query terms.

Score returned is the maximum of the operands.

 
'cats | dogs'
'cats OR dogs'

NOT

~

Use the NOT operator to search for documents that contain one query term and not another.

To obtain the documents that contain the term animals but not dogs, use the following expression:

'animals ~ dogs'

ACCUM

,

Use the ACCUM operator to search for documents that contain at least one occurrence of any of the query terms. The accumulate operator ranks documents according to the total term weight of a document.

The following query returns all documents that contain the terms dogs, cats and puppies giving the highest scores to the documents that contain all three terms:

'dogs, cats, puppies'

EQUIV

=

Use the EQUIV operator to specify an acceptable substitution for a word in a query.

The following example returns all documents that contain either the phrase alsatians are big dogs or German shepherds are big dogs:

'German shepherds=alsatians are big dogs'