if exists (select * from Relations where RelationTable='Free and occupied beds' and Colname='NumPeople') then
  update Relations
  set BGColName = 'Настанени'
  where RelationTable='Free and occupied beds' and Colname='NumPeople'
end if;

GO

if exists (select * from Relations where RelationTable='Free and occupied beds for period' and Colname='Students') then
  update Relations
  set BGColName = 'Настанени'
  where RelationTable='Free and occupied beds for period' and Colname='Students'
end if;