org.axiondb.functions
Class RowNumFunction

java.lang.Object
  extended byorg.axiondb.BaseSelectable
      extended byorg.axiondb.functions.BaseFunction
          extended byorg.axiondb.functions.RowNumFunction
All Implemented Interfaces:
ConcreteFunction, Function, FunctionFactory, ScalarFunction, Selectable, Serializable

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: 1.3 $ $Date: 2004/09/09 23:47:44 $
See Also:
Serialized Form

Constructor Summary
RowNumFunction()
           
 
Method Summary
 Object evaluate(RowDecorator row)
           
 DataType getDataType()
           
 boolean isValid()
           
 ConcreteFunction makeNewInstance()
           
 
Methods inherited from class org.axiondb.functions.BaseFunction
addArgument, getAlias, getArgument, getArgumentCount, getLabel, getName, setAlias, setArgument, setName, setVariableContext, toString
 
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 Object evaluate(RowDecorator row)
                throws AxionException
Specified by:
evaluate in interface ScalarFunction
Throws:
AxionException

isValid

public boolean isValid()
Specified by:
isValid in interface ConcreteFunction
Specified by:
isValid in class BaseFunction