SQL & PL/SQL

I have designed query , take which taking data from multiple tables and want to share update in one query. I am receiving error on the execution of code.

Error is ORA-00971: missing SET keyword

UPDATE 

APPS.PN_PROPERTIES_ALL P,   --- Table

APPS.PN_LOCATIONS_ALL L,   --- Table

APPS.EM_PN_PROPERTY_ATTRIBUTES A,   --- Table

APPS.HR_ALL_ORGANIZATION_UNITS OU  --- Table

SET L.FLOOR = 'CVR-ST 01'

SET A.UNIT_MODEL = 'CVR-ST-01'

WHERE

    P.PROPERTY_ID = A.PROPERTY_ID

AND L.LOCATION_ID = A.LOCATION_ID

AND P.ORG_ID = OU.ORGANIZATION_ID

AND P.ORG_ID = L.ORG_ID

AND L.ORG_ID = A.ORG_ID

AND L.ORG_ID IN (102,121)

AND L.LOCATION_TYPE_LOOKUP_CODE = 'OFFICE'

AND L.BUILDING LIKE '%CVR%'

AND L.FLOOR LIKE '%Plot%'

AND A.UNIT_MODEL LIKE 'Plot-1'