List the name of ships that are not involved in any mission
select name from ship where ship_id not in ( select ship_id from mission )
Which ships have been decommissioned?
select ship_id from mission where fate like '%decommissioned%'
Give me the names of ships that have been decommissioned
select name from ship where ship_id in ( select ship_id from mission where fate like '%decommissioned%' )