在rownum上的SQL查询 [英] Sql query on rownum

问题描述

SELECT instmax
FROM
  (SELECT instmax ,rownum r
  FROM
    ( SELECT instmax FROM pswlinstmax ORDER BY instmax DESC NULLS LAST
    )
  WHERE r = 2
  );

执行后，出现此错误:

ORA-00904: "R": invalid identifier
00904. 00000 -  "%s: invalid identifier"
*Cause:    
*Action:
Error at Line: 39 Column: 8

为什么会出现此错误?

推荐答案

因为同一查询的WHERE子句中不支持别名.因此，请像这样编写您的查询:

Because aliases are not supported in the WHERE clause of the same query. So instead write your query like:

SELECT instmax
FROM 
  (SELECT instmax ,rownum r 
  FROM 
    ( SELECT instmax FROM pswlinstmax ORDER BY instmax DESC NULLS LAST 
    )  
) WHERE r = 2;

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