sql - Oracle SQL NOT NULL x或NULL？

Question

我正在选择一组记录，并且想按XOR的逻辑过滤一列-IS NOT NULL xor IS NULL。

--basic
SELECT make, model
FROM cars

results
--------
ford   taurus
ford   (null)
toyota camry
toyota (null)
honda  (null)

--Obviously XOR is not a real Oracle operator
--This is what I'm trying to do..
SELECT make, model
FROM cars
WHERE model IS NOT NULL
  XOR model IS NULL 

results (pulls records where model IS NOT NULL, falling back to NULL if necessary)
--------
ford   taurus
toyota camry
honda  (null)

谁能为我提供有关如何获得所需结果的见解？我正在为此奋斗!

非常感谢!

Answer 1

SELECT  make, model
FROM    (
        SELECT  c.*,
                ROW_NUMBER() OVER (PARTITION BY make ORDER BY model NULLS LAST) AS rn
        FROM    cars c
        )
WHERE   NOT (rn > 1 AND model IS NULL)