org.axiondb.functions
Class RowNumFunction

java.lang.Object
  org.axiondb.BaseSelectable
      org.axiondb.functions.BaseFunction
          org.axiondb.functions.RowNumFunction

All Implemented Interfaces:

java.io.Serializable, Function, FunctionFactory, ConcreteFunction, ScalarFunction, Selectable

public class RowNumFunction
extends BaseFunction
implements ScalarFunction, FunctionFactory

Returns an one-based index indicating the order in which a row was selected from a table, join, etc.

Note that conditions testing whether ROWNUM() is greater than a positive integer will always fail (since for each tested row ROWNUM() will evaluate to 1).

Version:

$Revision: 1.4 $ $Date: 2005/03/01 22:58:42 $

See Also:

Serialized Form

Field Summary

Fields inherited from class org.axiondb.BaseSelectable

_hash

Constructor Summary

RowNumFunction()

Method Summary

java.lang.Object	evaluate(RowDecorator row)
DataType	getDataType()
boolean	isValid()
ConcreteFunction	makeNewInstance()

Methods inherited from class org.axiondb.functions.BaseFunction

addArgument, getArgument, getArgumentCount, setArgument, setVariableContext, toString

Methods inherited from class org.axiondb.BaseSelectable

getAlias, getLabel, getName, setAlias, setName

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.axiondb.Function

addArgument, getAlias, getArgument, getArgumentCount, getName, setAlias, setArgument

Methods inherited from interface org.axiondb.Selectable

getLabel, setVariableContext

Constructor Detail

RowNumFunction

public RowNumFunction()

Method Detail

makeNewInstance

public ConcreteFunction makeNewInstance()

Specified by:

makeNewInstance in interface FunctionFactory

getDataType

public DataType getDataType()

Specified by:

getDataType in interface Selectable

Specified by:

getDataType in class BaseFunction

evaluate

public java.lang.Object evaluate(RowDecorator row)
                          throws AxionException

Specified by:

evaluate in interface ScalarFunction

Specified by:

evaluate in interface Selectable

Throws:

AxionException

isValid

public boolean isValid()

Specified by:

isValid in interface ConcreteFunction

Specified by:

isValid in class BaseFunction