Query that shows all rows but not all data in all rows
Solution 1:
You want a case expression to conditionally show the EventType.
select ItemID, CustomerID
, case when EventType = 'On Order' then EventType else '' end EventType
from InventoryEvents;
Solution 2:
Sounds like you want a CASE expression:
SELECT CustomerID,
ItemID,
CASE WHEN EventType <> 'On Order' THEN '' ELSE EventType END AS EventType
FROM InventoryEvents;