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/BindingColumnsEvalUtil.java
return bindingColumn;
			}
		}
		throw new DataException( ResourceConstants.INVALID_BOUND_COLUMN_NAME,
				name );
	}
	/**
	 * A simple wrapper for binding column
	 */
	private class BindingColumn
	{
		
		private String columnName;
		private IBaseExpression baseExpr;
		private boolean isAggregation;
		private int type;
		
		private BindingColumn( String columnName, IBaseExpression baseExpr, boolean isAggregation, int type )
		{
			this.columnName = columnName;
			this.baseExpr = baseExpr;
			this.isAggregation = isAggregation;
			this.type = type;
			if ( this.baseExpr instanceof ScriptExpression )
			{
				( (ScriptExpression) this.baseExpr ).setDataType( type );
			}
		}
	}