请问如何重新组织数据库中所有索引？

declare R_T cursor
for select name from sys.tables
declare @T varchar(50)
open r_t
fetch next from r_t into @t
while @@fetch_status=0
begin
--R_index游标判断指定表索引碎片情况并优化
declare R_Index cursor
for 
select t.name,i.name,s.avg_fragmentation_in_percent from sys.tables t
  join sys.indexes i on i.object_id=t.object_id
  join sys.dm_db_index_physical_stats(db_id(),object_id(@T),null,null,'limited') s
   on s.object_id=i.object_id and s.index_id=i.index_id
declare @TName varchar(50),@IName varchar(50),@avg int,@str varchar(500)
open r_index
fetch next from r_index into @TName,@Iname,@avg
while @@fetch_status=0
begin
  if @avg>=30  --如果碎片大于,重建索引
  begin
   set @str='alter index '+rtrim(@Iname)+' on dbo.'+rtrim(@tname)+' rebuild'
  end
  if @avg<30 and @avg>10  --如果碎片小于,重新组织索引
  begin
   set @STR='alter index '+rtrim(@Iname)+' on dbo.'+rtrim(@tname)+' reorganize'
  end
  print @str
  exec (@str)  --执行
  fetch next from r_index into @TName,@Iname,@avg
end
--结束r_index游标
close r_index
deallocate r_index
fetch next from r_t into @t
end
--结束R_T游标
close r_t
deallocate r_t