sql server 将两列的值合并到另一列

select top 100 t2.FullName, * from Subject,(select id, isnull(first_name,'') +isnull(middle_name,'') + ' '+isnull(last_name,'') as FullName from Subject ) T2 where Subject.id = T2.id and T2.id = 372

--update Subject set Subject.full_name = T2.FullName from Subject,(select id, isnull(first_name,'') +isnull(middle_name,'') + ' '+ isnull(last_name,'') as FullName from Subject ) T2 where Subject.id = T2.id --and T2.id = 372