DB2 SQL错误代码-255

Question

我之前从未见过这个错误代码，也找不到任何相关文档。这是查询：

WITH QUERY AS (
    SELECT rrn(T1), blah, bleh, 
        ROW_NUMBER() OVER (order by  bleh desc) AS RN  
    FROM T1 
    WHERE (
        upper(blah) like ('%WEST%') 
     OR upper(bleh) like ('%WEST%')
    ) 
) 
SELECT * FROM QUERY WHERE RN BETWEEN 1 AND 10

仅在应用upper（）时才会发生错误。

错误消息是＆＃34;查询＆＃34;不支持该功能。