Declare @master table (id int,name varchar(100))
insert into @master values(1,'a'),(2,'b'),(3,'c')
Declare @details table (id int,name varchar(100))
insert into @details values(2,'b2'),(2,'b3')
update a set name=b.name from @master a
inner join @details b on a.id = b.id
select * from @master
