com.simba.dsi.ext.aetree
Class AEProject

java.lang.Object
  extended by com.simba.dsi.CppClassWrapper
      extended by com.simba.dsi.ext.aetree.AENode
          extended by com.simba.dsi.ext.aetree.AEQueryOperation
              extended by com.simba.dsi.ext.aetree.AERelationalExpr
                  extended by com.simba.dsi.ext.aetree.AEUnaryRelationalExpr
                      extended by com.simba.dsi.ext.aetree.AEProject

public final class AEProject
extends AEUnaryRelationalExpr

This class models an extended project relational operation: PI(R), where a is the project list, R is the relation to operate upon.

In the standard relational algebra, a can only be a list of attributes (columns) of R. Here we allow a being a list of value expressions defined on the attributes of R. Also, repeated value expressions are allowed. That is, one can have more than one identical value expressions.

In SQL-92, AEProject class models a simple SELECT-FROM query that involves only one table and a subset of all the columns of the table. For example, the following query can be translated to an AEProject operation directly.

 SELECT A.C1 A.C2 FROM A
 


Constructor Summary
AEProject(long objRef)
          Constructor.
 
Method Summary
 AEValueList getProjectionList()
          Retrieves the projection list.
 
Methods inherited from class com.simba.dsi.ext.aetree.AEUnaryRelationalExpr
getOperand
 
Methods inherited from class com.simba.dsi.ext.aetree.AERelationalExpr
isNamed
 
Methods inherited from class com.simba.dsi.ext.aetree.AEQueryOperation
getColumn, getColumnCount
 
Methods inherited from class com.simba.dsi.ext.aetree.AENode
getChild, getChildCount, getNodeType
 
Methods inherited from class com.simba.dsi.CppClassWrapper
getObjRef
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

AEProject

public AEProject(long objRef)
Constructor.

Parameters:
objRef - The corresponding C++ object reference.
Method Detail

getProjectionList

public AEValueList getProjectionList()
Retrieves the projection list.

Returns:
The projection list.


Copyright © 2006-2014 Simba Technologies Incorporated. All Rights Reserved.