sql - 用 sql 查询返回 0 而不是什么都没有

Question

如果计数为 0，我如何返回一个 0 和作为可能的AnswerText 的响应？现在它不会返回任何东西。

select 
    COUNT(sr.Id) AS 'Responses', qpa.PossibleAnswerText
from 
    CaresPlusParticipantSurvey.QuestionPossibleAnswer as qpa 
join  
    CaresPlusParticipantSurvey.SurveyResponse as sr on sr.QuestionPossibleAnswerId = qpa.Id
where 
    sr.QuestionPossibleAnswerId = 116 
GROUP BY 
    qpa.PossibleAnswerText

Answer 1

您需要使用, 并从子句LEFT JOIN中删除“最右边”表上的条件；WHERE

SELECT COUNT(sr.Id) AS 'Responses', qpa.PossibleAnswerText
FROM CaresPlusParticipantSurvey.QuestionPossibleAnswer AS qpa 
LEFT JOIN CaresPlusParticipantSurvey.SurveyResponse as sr 
  ON sr.QuestionPossibleAnswerId = qpa.Id
WHERE qpa.Id = 116 
GROUP BY qpa.PossibleAnswerText