数据库日期年月期间段

sql server 数据库，日期期间段查询。
a.id+b.id*10+c.id*100+d.id*1000 表示从0到9999一共一万的连续数。
convert(varchar(10),dateadd(day,id,'2003-03-06'),120) 是获取到从指定日期开始连续的10000天日期，然后根据需要获取时间段获取日期。再把日期转化为字符串，用left（）函数取得年和月，用distinct过滤重复数据，也就得到了，期间段年月

select distinct left(convert(varchar(10),dateadd(day,id,'2003-03-06'),120),7) AS [DATE] from (
  select id=a.id+b.id*10+c.id*100+d.id*1000 from  
  (
  select id=0 union all select id=1
  union all select id=2 union all select 3
  union all select id=4 union all select 5
  union all select id=6 union all select 7
  union all select id=8 union all select 9
  ) a,(
  select id=0 union all select id=1
  union all select id=2 union all select 3
  union all select id=4 union all select 5
  union all select id=6 union all select 7
  union all select id=8 union all select 9
  ) b,(
  select id=0 union all select id=1
  union all select id=2 union all select 3
  union all select id=4 union all select 5
  union all select id=6 union all select 7
  union all select id=8 union all select 9
  ) c,(
  select id=0 union all select id=1
  union all select id=2 union all select 3
  union all select id=4 union all select 5
  union all select id=6 union all select 7
  union all select id=8 union all select 9
  ) d
  ) aa
  where dateadd(day,id,'2003-03-06')<'2004-05-01'
ORDER BY  [DATE]