For Requisitions waiting approval how can I tell who the approval is waiting on

We need to know for open requisitions waiting approval, who has the requisition routed to them for approval at that time?  I am trying to write a query to get that data.  Can you tell me which table hold that data?  I found in po.po_approval_list_lines it has an approver_id.  This is the person the requisition was first sent to.  If that person has their vacation rules on or if your manually forward the approval in via the workflow status monitor it does not update the po.po_approval_list_lines with the new approver.  In Workflow Status Monitor it shows who the requisition is