CTE error: “Types don't match between the anchor and the recursive part”

问题

I am executing the following statement:

;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

...which finishes with the error...

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".

Where am I making the mistake?

回答1:

Exactly what it says:

'name1' has a different data type to 'name' + CAST((rn+1) as varchar(255))

Try this (untested)

;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

Basically, you have to ensure the length matches too. For the recursive bit, you may have to use CAST('name' AS varchar(4)) if it fails again

回答2:

You need to cast both nm fields

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

回答3:

For me problem was in different collation.

Only this helped me:

;WITH cte AS (
  SELECT 
    1 AS rn, 
    CAST('name1' AS NVARCHAR(4000)) COLLATE DATABASE_DEFAULT AS nm
  UNION ALL
  SELECT 
    rn + 1,
    nm = CAST('name' + CAST((rn + 1) AS NVARCHAR(255)) AS NVARCHAR(4000)) COLLATE DATABASE_DEFAULT
  FROM cte a WHERE rn < 10)
SELECT * 
FROM cte;

Hope it can help someone else.

回答4:

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

回答5:

In my case, I messed up the sequence of columns in top and bottom clauses of UNION ALL. And it turned out that a varchar column appeared 'under' an int one. An easy mistake to make of you have lots of columns

回答6:

I would recommend using nvarchar(max)

WITH CTE AS (
SELECT x,x_name FROM (VALUES (1,CAST('' AS nvarchar(MAX)))) AS     test(x,x_name)
UNION ALL
SELECT x + 1 x, CONCAT(x_name,x+1)  FROM CTE WHERE x < 10 )
SELECT * FROM CTE

回答7:

If you use CONCAT in the recursive term of a rcte, since the output type of concat is varchar(MAX), you only need to cast the column in the initial query:

WITH rcte AS (
    SELECT 1 AS nr, CAST('1' AS varchar(MAX)) AS trail
    UNION ALL
    SELECT nr+1, CONCAT(trail, '/', nr+1)
    FROM rcte
    WHERE nr < 5
)
SELECT * FROM rcte;

回答8:

WITH rcte AS (
    SELECT 1 AS nr, CAST('1' AS varchar(MAX)) AS trail
    UNION ALL
    SELECT nr+1, cast(CONCAT(trail, '/', nr+1) as varchar(max))
    FROM rcte
    WHERE nr < 5
)
SELECT * FROM rcte;

回答9:

;with tmp1(NewsId,DataItem ,HeaderText)
 as
  (

    select NewsId, LEFT(HeaderText, CHARINDEX(',',HeaderText+',')-1),
    STUFF(HeaderText, 1, CHARINDEX(',',HeaderText+','), '') 
    from Currentnews

    union all

    select NewsId, LEFT(HeaderText, CHARINDEX(',',HeaderText+',')-1),
    STUFF(HeaderText, 1, CHARINDEX(',',HeaderText+','), '')
    from tmp1
    where HeaderText > ''

   )

   select NewsId, DataItem
   from tmp1
   order by NewsId

来源：https://stackoverflow.com/questions/1838276/cte-error-types-dont-match-between-the-anchor-and-the-recursive-part

标签

sql

sql-server

tsql

common-table-expression