To associate a query with a dynamic Data-Source object, use the QUERY attribute. To disassociate the query and Data-Source object, set this attribute to the Unknown value (?). You can also use the FILL-WHERE-STRING attribute to override the WHERE clause in the query.
Note: The FILL-WHERE-STRING attribute of the data source object only applies to the default data source query. It does not apply when a named query is specified using the QUERY attribute.

For a Data-Relation object, the QUERY attribute returns the handle to the default dynamic query for a child buffer in the relation. This automatically-generated query expresses the relation between parent and child temp-tables, and lets you navigate the child records. You cannot set this handle nor can you modify the query.

For a buffer object, the QUERY attribute returns the handle to the query currently associated with the buffer (if any). If the buffer does not have an associated query, this attribute returns the Unknown value (?). This attribute is also read-only for a buffer object.