One of the reasons attributed to the great success of relational database technology has been the existence of a high-level, declarative, query language, which allows an application to express what conditions must be satisfied by the data it needs, rather than having to specify how to get the required data. Given the large number of patterns that may be mined, there appears to be a definite need for a mechanism to specify the focus of the analysis. Such focus may be provided in at least two ways. First, constraints may be placed on the database (perhaps in a declarative language) to restrict the portion of the database to be mined for, e.g. [MJHS96]. Second, querying may be performed on the knowledge that has been extracted by the mining process, in which case a language for querying knowledge rather than data is needed. An SQL-like querying mechanism has been proposed for the WEBMINER system [MJHS96], details of which are provided in section 5.