sql - CTE错误: "Types don' t match between the anchor and the recursive part"

Question

我正在执行以下语句:

;WITH cte AS (
  SELECT 
    1 as rn, 
    'name1' as nm
  UNION ALL
  SELECT 
    rn + 1,
    nm = 'name' + CAST((rn + 1) as varchar(255))
  FROM cte a WHERE rn < 10)
SELECT * 
FROM cte

...最终出现错误...

Msg 240, Level 16, State 1, Line 2
Types don't match between the anchor and the recursive part in column "nm" of recursive query "cte".

我哪里出错了？

Answer 1

正如它所说:

'name1' 的数据类型与 'name' + CAST((rn+1) as varchar(255))

不同

试试这个(未经测试)

;with cte as
(
select 1 as rn, CAST('name1' as varchar(259)) as nm
union all
select rn+1,nm = 'name' + CAST((rn+1) as varchar(255))
from cte a where rn<10)
select * from cte

基本上，您也必须确保长度匹配。对于递归位，如果再次失败，您可能必须使用CAST('name' AS varchar(4))