There are probably better ways, but I think this works:

; WITH AllActions (ItemID, ActionID)

AS

(

SELECT distinct

i.itemid

, a.actionid

FROM items i

CROSS APPLY

( select a.actionid

FROM Actions a

) a

)

SELECT

*

FROM AllActions aa

WHERE aa.itemid NOT IN (select i.itemid

FROM items i

WHERE aa.itemid = i.ItemID

AND aa.ActionID = i.ActionID

)

ORDER BY

itemid

, ActionID