Bug 195970 Two issues when evaluate a query inlcuding a subquery[07]
Description: Currently, when evaluating a query which includes a subquery, the query will be evaluated twice. The binding of query will pass to subquery twice. If user write a java script such as new Date() and i++. The result of query will be incorrect. Another issue: when write the report document, the binding of query will be written twice and the performance is not good to evalulate it twice.
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/impl/ExprManagerUtil.java
l = ExpressionCompilerUtil.extractColumnExpression( (IConditionalExpression) expr );
				}
				catch ( DataException e )
				{
					
					
				}
				
				if ( l != null )
				{
					for ( int j = 0; j < l.size( ); j++ )
					{
						n.addChild( new Node( l.get( j ) == null ? null
								: l.get( j ).toString( ) ) );
					}
				}
			}
			result.add( n );
		}
		Node[] source = new Node[result.size( )];
		for ( int i = 0; i < source.length; i++ )
		{
			source[i] = (Node) result.get( i );
		}
		validateNodes( source );
	}
	
	/**
	 * Check whether the expression of all the column bindings is valid.
	 *