Query Expressions

A query expression is everything in between the single quotes in the text_query argument of the CONTAINS or CATSEARCH operator. What you can include in a query expression in a CONTAINS query is different from what you can include in a CATSEARCH operator.

CONTAINS Operators

A CONTAINS query expression can contain query operators that enable logical, proximity, thesaural, fuzzy, and wildcard searching. Querying with stored expressions is also possible. Within the query expression, you can use grouping characters to alter operator precedence. This book refers to these operators as the CONTEXT grammar.

With CONTAINS, you can also use the ABOUT query to query document themes.

CATSEARCH Operator

With the CATSEARCH operator, you specify your query expression with the text_query argument and your optional structured criteria with the structured_query argument. The text_query argument enables you to query words and phrases. You can use logical operations, such as logical and, or, and not. This book refers to these operators as the CTXCAT grammar.

If you want to use the much richer set of operators supported by the CONTEXT grammar, you can use the query template feature with CATSEARCH.

With structured_query argument, you specify your structured criteria. You can use the following SQL operations:

=
<=
>=
>
<
IN
BETWEEN

You can also use ORDER BY clause to order your output.

MATCHES Operator

Unlike CONTAINS and CATSEARCH, MATCHES does not take a query expression as input.

Instead, the MATCHES operator takes a document as input and finds all rows in a query (rule) table that match it. As such, you can use MATCHES to classify documents according to the rules they match.