T-SQL CTE 错误：锚点和递归部分之间的类型不匹配

Question

当我尝试执行特定的递归 CTE 时，出现以下错误：

Msg 240, Level 16, State 1, Line 8
Types don't match between the anchor and the recursive part in column "data_list" of recursive query "CTE".

这是无意义的。每个字段都显式转换为 VARCHAR(MAX)。 请帮我。我在这里和其他地方读过这个问题的许多答案，所有这些答案都建议明确地转换有问题的专栏。我已经这样做了，但仍然收到错误。

此代码将重现错误：

if object_id('tempdb..#tOwner') IS NOT NULL drop table #tOwner;
CREATE TABLE #tOwner(id int identity(1,1), email varchar(max) );
insert into #towner values ( cast('[email protected]'  as varchar(max)));
insert into #towner values ( cast('tsql rage'    as varchar(max)));
insert into #towner values ( cast('[email protected]'  as varchar(max)));
insert into #towner values ( cast('einstein.x.m' as varchar(max)));

;WITH data AS (
    SELECT DISTINCT convert(varchar(max), email) datapoint FROM #tOwner 
), CTE ( data_list, datapoint, length ) AS ( 
        SELECT convert(VARCHAR(max),            ''           ),convert(VARCHAR(max),    ''     ),       0
    UNION ALL
        SELECT convert(VARCHAR(max),d.datapoint+';'+data_list),convert(VARCHAR(max),d.datapoint), length + 1
        FROM CTE c CROSS JOIN data d WHERE d.datapoint > c.datapoint 
)
SELECT D.data_list
FROM ( 
    SELECT data_list, RANK() OVER ( PARTITION BY 1 ORDER BY length DESC ) 
    FROM CTE 
) D ( data_list, rank )
WHERE rank = 1 ;

drop table #tOwner;

如果您发现相关，SELECT left(@@VERSION, 70) 返回：

Microsoft SQL Server 2005 - 9.00.4053.00 (X64)   May 26 2009 14:13:01 

Answer 1

Will A 对我原始帖子的评论找到了关键 - 整理。我发布的查询在主数据库中也对我有用。

检查整理表明我走在正确的轨道上。

SELECT DATABASEPROPERTYEX('crm_mscrm', 'Collation') crmSQLCollation
crmSQLCollation
--------------------
Latin1_General_CI_AI
(1 row(s) affected)

SELECT DATABASEPROPERTYEX('master', 'Collation') masterSQLCollation
masterSQLCollation
----------------------------
SQL_Latin1_General_CP1_CI_AS
(1 row(s) affected)

后来进行了一些疯狂的搜索，我得到了这个怪物般的代码，它

1. 显式地指定了每列的排序规则，
2. 成功执行并
3. 返回了预期的结果

也就是说：

if object_id('tempdb..#tOwner') IS NOT NULL drop table #tOwner;
CREATE TABLE #tOwner(id int identity(1,1), email nvarchar(max) );
insert into #towner values ( cast('[email protected]'  as nvarchar(max)));
insert into #towner values ( cast('tsql rage'    as nvarchar(max)));
insert into #towner values ( cast('[email protected]'  as nvarchar(max)));
insert into #towner values ( cast('einstein.x.m' as nvarchar(max)));

;WITH data AS (
    SELECT DISTINCT convert(nvarchar(max), email) datapoint FROM #tOwner 
), CTE ( data_list, datapoint, length ) AS ( 
        SELECT convert(nvarchar(max),            ''           ) Collate SQL_Latin1_General_CP1_CI_AS,convert(nvarchar(max),    ''     ) Collate SQL_Latin1_General_CP1_CI_AS,       0
    UNION ALL
        SELECT convert(nvarchar(max),d.datapoint+';'+data_list) Collate SQL_Latin1_General_CP1_CI_AS,convert(nvarchar(max),d.datapoint) Collate SQL_Latin1_General_CP1_CI_AS, length + 1
        FROM CTE c CROSS JOIN data d WHERE d.datapoint > c.datapoint 
)
SELECT D.data_list
FROM ( 
    SELECT data_list, RANK() OVER ( PARTITION BY 1 ORDER BY length DESC ) 
    FROM CTE 
) D ( data_list, rank )
WHERE rank = 1 ;

if object_id('tempdb..#tOwner') IS NOT NULL drop table #tOwner;

在我的结果窗口中漂亮地坐着是预期的：

data_list
------------------------------------------------
tsql rage;einstein.x.m;[email protected];[email protected];