I want to highlight Query to get workflow last comment in Ax 2012. You can use ,WorkflowTrackingTable,WorkflowTrackingStatusTable and WorkflowTrackingCommentTable to get Last comment entered by used on submitting or approving workflow for module
WorkflowTrackingTable workflowTrackingTable;
WorkflowTrackingStatusTable workflowTrackingStatusTable;
WorkflowTrackingCommentTable workflowTrackingCommentTable;
PurchTable PurchTable;
select PurchTable where PurchTable.PurchId ="PO13000003";
select ContextCompanyId, ContextTableId, ContextRecId from workflowTrackingStatusTable
where workflowTrackingStatusTable.ContextCompanyId == curext()
&& workflowTrackingStatusTable.ContextTableId == PurchTable.TableId
&& workflowTrackingStatusTable.ContextRecId == PurchTable.RecId
join firstonly TrackingId, CreatedDateTime from workflowTrackingTable order by CreatedDateTime desc
where workflowTrackingTable.WorkflowTrackingStatusTable == workflowTrackingStatusTable.RecId
join Comment from workflowTrackingCommentTable
where workflowTrackingCommentTable.WorkflowTrackingTable == workflowTrackingTable.RecId;
info( workflowTrackingCommentTable.Comment);