mysql - 计算联接表中的行，但如果不存在行则显示0-MySQL

响应头表是一个联接表，它被计算为显示对特定调查的响应。如果没有行，因此没有响应，我希望计数显示0。但它将跳过行，因为在表中找不到联接参数（survey_id）。

SELECT DATE_FORMAT(launched_date,'<nobr>%e-%b-%Y %H:%i:%s</nobr>'),
survey.NAME,
survey.iris_type,
survey.launched_by,
COUNT(response_header_2010.survey_id) AS response_count,
survey.survey_id,
survey.NAME

FROM survey, response_header_2010

WHERE survey.STATUS='Live'
AND survey.iris_type!='Recipient List'
AND response_header_2010.survey_id = survey.survey_id
AND client_id = '98'

GROUP BY  survey.survey_id, survey.NAME

ORDER BY response_count

最佳答案

您希望使用左联接，而不是当前的内部联接。

SELECT DATE_FORMAT(launched_date,'<nobr>%e-%b-%Y %H:%i:%s</nobr>'),
survey.NAME,
survey.iris_type,
survey.launched_by,
COUNT(response_header_2010.survey_id) AS response_count,
survey.survey_id,
survey.NAME

FROM survey
LEFT JOIN response_header_2010
    ON survey.survey_id = response_header_2010.survey_id
WHERE survey.STATUS='Live'
AND survey.iris_type!='Recipient List'
AND client_id = '98'

GROUP BY  survey.survey_id, survey.NAME

ORDER BY response_count

关于mysql - 计算联接表中的行，但如果不存在行则显示0-MySQL，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/4686003/