fun ltDB(columnName: List<String>, k: PairIntIntKey): String (source)
DB query for 'less than' relationship.
Returns the string querying underlying DB for all elements having key (attribute) less than a given value. Underlying dataset must know how to interpret the query, and return the expected result.
columnName - the list of the names of the database columns interested in the comparison
(they represent the k_min or k_max columns); since this method is only
invoked from connector's queries, this field must identify K in the database
(it is recommended to use this.keyColumnsDefinitionDB() to generate this list).
Return
the string to be interpreted by underlying database as 'k_min < k' ('k_max < k').