First (query directive)

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.