Bug 213907 Provide a copy constructor for SubqueryDefinition.
Engine need a copy constructor to generate a SubqueryDefinition from an ISubqueryDefinition and change the name of the query.
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/impl/PreparedQuery.java
* @return
	 */
	private IConditionalExpression transformConditionalExpression(
			IConditionalExpression ce )
	{
		String prefix = null;
		
		switch ( ce.getOperator( ) )
		{
			case IConditionalExpression.OP_TOP_N :
				prefix = "Total.isTopN";
				break;
			case IConditionalExpression.OP_TOP_PERCENT :
				prefix = "Total.isTopNPercent";
				break;
			case IConditionalExpression.OP_BOTTOM_N :
				prefix = "Total.isBottomN";
				break;
			case IConditionalExpression.OP_BOTTOM_PERCENT :
				prefix = "Total.isBottomNPercent";
				break;
		}
		
		if( prefix != null )
		{
			ce = new ConditionalExpression( prefix +
					"(" + ce.getExpression( ).getText( ) + "," +
					( (IScriptExpression) ce.getOperand1( ) ).getText( ) + ")",
					IConditionalExpression.OP_TRUE );
		}