私はこのクエリを持っています
select devlocview.ENTERPRISENAME
FROM AlarmDeviceView alrmDevView
INNER JOIN devicelocationview devLocView 
    ON devlocview.oid=alrmdevview.deviceoid
LEFT OUTER JOIN DEVICEGROUPVIEW devGrpView 
    ON devlocview.oid=devgrpview.deviceoid
LEFT OUTER JOIN RackCapacityView rackCapView 
    ON devlocview.RACKID=rackCapView.oid
WHERE 
(
    alrmdevview.createddate = ( select max(alview.createddate) 
                                from alarmdeviceview alview 
                                WHERE alview.alarmoid=alrmdevview.alarmoid) 
    or alrmdevview.createddate IS NULL
)
AND devlocview.ENTERPRISENAME='Enterprise1'
AND devlocview.buildingname in (
CASE
WHEN $p{building} IS  not NULL THEN $p{building}
WHEN $p{building} IS  NULL THEN (select buildingname from cdmr.devicelocationview)
END
)
ここで、この部分"select buildingname from cdmr.devicelocationview"は複数の行を返します。
01427としての例外。00000-「単一行のサブクエリは複数の行を返します」
要件に従って、複数の建物を割り当てたい場合$p{building} is  null