sql计算表达式

create table #t(A varchar(10),b numeric(28,2))
insert into #t select '1*2*3',null
insert into #t select '2*3*4',NULL

declare @sql nvarchar(4000)
select @sql = isnull(@sql+' ','')+'Update #t set B = ' + A + ' where A=''' + A+ ''''
from #t

exec( @sql)
select * from #t
drop table #t