Question

此查询：

SELECT colour FROM ColourView EXCEPT SELECT colour FROM SkinColourExceptionsView WHERE race = 'Human' ORDER BY RANDOM() LIMIT 1

产生以下异常：1st ORDER BY term does not match any column in the result set

但是，将ORDER BY RANDOM()更改为ORDER BY colour可以生成结果（按颜色按字母顺序排序，而不是随机排序）。以下建议ORDER BY RANDOM() LIMIT 1应该有效：Select random row from an sqlite table。有人可以解释为什么我的查询不起作用吗？

Answer 1

在compound query中，ORDER BY术语必须与结果集中的某些列匹配。

您可以通过将复合查询移动到子查询中来解决此限制：

SELECT colour
FROM (SELECT colour FROM ColourView
      EXCEPT
      SELECT colour FROM SkinColourExceptionsView WHERE race = 'Human')
ORDER BY random()
LIMIT 1;

或者，重写查询以使用不同的过滤机制：

SELECT colour
FROM ColourView
WHERE colour NOT IN (SELECT colour
                     FROM SkinColourExceptionsView
                     WHERE race = 'Human')
ORDER BY random()
LIMIT 1;

SQLite：... EXCEPT ... ORDER BY RANDOM（）

1 个答案: