左/右加入问题

Question

不知道该怎么做。

我有两个表格结果和受访者

我需要查看响应者表中是否有任何行具有completion ='Complete'但是他们的respondent_id（在结果表和响应者表中都是）不在结果表中？

有什么想法吗？

Answer 1

SELECT respondent.* FROM respondent LEFT JOIN results 
ON respondent.id = results.id
WHERE results.id IS NULL;
AND respondents.completion = 'Complete'

Answer 2

或许类似于此。

SELECT r1.* FROM respondents r1
    LEFT JOIN results r2 ON r1.respondent_id = r2.respondent_id
    WHERE r1.completition = 'Complete' AND r2.respondent_id IS NULL;