Try like this....
declare @interest table (id int identity not null, ColA varchar(10) null, ColB varchar(10) null, ColC varchar(10) null)
insert into @interest (ColA, ColB, ColC)
values
(null, null, '1.1%')
,('3.2%', '1.1%', '2.0%')
declare @description table (id int identity not null, NewColumn varchar(30))
insert into @description (NewColumn)
(select coalesce(ColA,'0.0%')+', '+coalesce(ColB, '0.0%')+', '+coalesce(ColC,'0.0%')
from @interest)
select * from @description
(2 row(s) affected)
(2 row(s) affected)
id NewColumn
1 0.0%, 0.0%, 1.1%
2 3.2%, 1.1%, 2.0%
(2 row(s) affected)