ORACLE: Changing the grouping of a data to be based on month breakdowns
I figured it out, 
had to group by trucn(invdate,'mm') and count the separate columns

SELECT TO_CHAR(TRUNC(inv.invdate,'MM'),'MON-RR') "Month",
         COUNT(DISTINCT(inv.order_no)) "Orders",
         COUNT(inv.order_no) "Order Lines",
         COUNT(DISTINCT(inv.invoice_no)) "Invoices",
         COUNT(inv.invoice_no) "Invoice Lines",
         COUNT(DISTINCT(inv.name)) "Companies"
FROM test.test1 inv
GROUP BY TRUNC(inv.invdate,'MM')