Select from a table where column row has Zero (0) or Zeros (000000)
Something like, if your acctno has empty strings you will need to elaborate this query a bit
create table #t (name varchar(20), acctno varchar(30))

insert #t values ('Tim', '000')
insert #t values ('Jim', '00750')
insert #t values ('Bim', '0000000')

select * from #t where replace(acctno, '0','') = ''