First (query directive)

Revision as of 09:29, 21 August 2009

Description

Returns the first or the first N rows of specified directive. May return less than specified number of rows if the inner directive does not return that many rows.

Constructor

First(Directive directive) - Returns the first row of directive.

First(int count, Directive directive) - Returns the first count rows of directive

Examples

importPackage(org.wandora.query2);
new If(
  new Exists(new BaseName().where("#DEFAULT","!=",null)),
  new BaseName(),
  new First(new SubjectIdentifiers())
)
.from(new Instances())

This returns the base names of the instances of the input topic or the first subject identifier if the base name is not defined.