Error Message:
Msg 462, Level 16, State 1, Line 1
Outer join is not allowed in the recursive part of a recursive common table expression ‘%.*ls’.
Severity level:
16.
Description:
This error message appears when you try to use an OUTER JOIN in the recursive part of a Common Table Expression.
Consequences:
The T-SQL statement can be parsed, but causes the error at runtime.
Resolution:
Error of the Severity Level 16 are generated by the user and can be fixed by the SQL Server user. The statement cannot be executed this way. The OUTER JOIN must be removed.
Versions:
This error message was introduced with SQL Server 2005.
Example(s):
USE tempdb;
GO
IF OBJECT_ID(‘tempdb..#t’) > 0
DROP TABLE #t
GO
CREATE TABLE #t
(
id INT,
reportToID INT NULL,
)
INSERT INTO #t SELECT 1, NULL
UNION ALL SELECT 2, 1
UNION ALL SELECT 3, 1
UNION ALL SELECT 4, 2
GO
WITH MyCTE (id, reportToID, Level)
AS
(
SELECT t1.ID, t1.reportToID, 0 AS Level
FROM #t AS t1
WHERE reportToID IS NULL
UNION ALL
SELECT t1.ID, t1.reportToID, Level
FROM #t AS t1
LEFT JOIN MyCTE AS t2
ON t1.reportToID = t2.ID
)
SELECT *
FROM MyCTE
GO
Remarks:
In the above example we try to use an OUTER JOIN in the recursive part of a Common Table Expression. This raises the error.