Chapter 8: Verity Topics

Relational operators

Relational operators search document fields (such as AUTHOR) that have been defined in the collection. These operators perform a filtering function by selecting documents that contain specified field values. The fields that are used with relational operators can contain alphanumeric characters. Documents retrieved using relational operators are not relevance-ranked, and you cannot use the MANY modifier with relational operators.

When creating topics, relational operators are always used in conjunction with the special FILTER operator. See the example under the topic “visual-arts” in “Sample Topic Outlines” later in this section for the proper syntax.

A number of relational operators are available for numeric and date comparisons, including the following: = (equals), > (greater than), >= (greater than or equal to), < (less than), <= (less than or equal to).

A number of relational operators are available for text comparisons, including the following.

**Table 8-3: Relational operators**
Operator name	Description
CONTAINS	Selects documents by matching the word or phrase you specify with values stored in a specific document field.
MATCHES	Selects documents by matching the character string you specify with values stored in a specific document field.
STARTS	Selects documents by matching the character string you specify with the starting characters of the values stored in a specific document field.
ENDS	Selects documents by matching the character string you specify with the ending characters of the values stored in a specific document field.
SUBSTRING	Selects documents by matching the character string you specify with a portion of the strings of the values stored in a specific document field.

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