10

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".

这是无稽之谈。每个字段都显式转换为VARCHAR(MAX). 请帮我。我已经在这里和其他地方阅读了很多关于这个问题的答案，所有这些答案都建议明确地选择有问题的列。我已经这样做了，但仍然得到错误。

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('123@123.321'  as varchar(max)));
insert into #towner values ( cast('tsql rage'    as varchar(max)));
insert into #towner values ( cast('another@e.c'  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;

如果您发现它相关，则SELECT left(@@VERSION, 70)返回：

Microsoft SQL Server 2005 - 9.00.4053.00 (X64)   May 26 2009 14:13:01
4

1 回答 1

11

Will A对我原帖的评论找到了关键——排序规则。我发布的查询在主数据库中也对我有用。

检查排序规则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)

后来经过一番疯狂的搜索，我得到了这个怪物的代码，

  1. 明确指定每一列的排序规则，
  2. 成功执行，并且
  3. 返回预期结果

以机智：

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('123@123.321'  as nvarchar(max)));
insert into #towner values ( cast('tsql rage'    as nvarchar(max)));
insert into #towner values ( cast('another@e.c'  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;another@e.c;123@123.321;
于 2010-08-06T22:59:44.183 回答