如何条件 SQL WHERE

Question

我想确定何时 GROUP_CONCAT 我的结果。我不知道如何区分 'category' 和 'condition' 结果。

SELECT d.company_name AS 'organisation name',
       GROUP_CONCAT(DISTINCT tag.tag) AS 'category',
       GROUP_CONCAT(DISTINCT tag.tag) AS 'conditions', d.contact_describtion AS 'description', d.tel, d.tel2, d.mobile, d.email, d.email2, d.web, d.web2, d.address, d.town, d.county, d.post_code AS 'post code', IF(d.state = 1, "published", "unpublished") AS 'status',d.contact_page_notes AS 'contact history', d.last_contacted_date AS 'last contacted', d.last_updated_date AS 'last updated'
FROM jds4a_directory d INNER JOIN
     jds4a_tags_resources res
     on d.id = res.resource_id INNER JOIN
     jds4a_tags tag
     on tag.id = res.tag_id
WHERE tag.category = 'condition' OR tag.category = 'category'
GROUP BY res.resource_id

我想实现的是在category下只显示category标签，conditions下只显示condition标签

Answer 1

使用case。您还返回了太多列，我认为：

SELECT d.company_name AS organisation_name,
       GROUP_CONCAT(DISTINCT (CASE WHEN tag.category = 'condition' THEN tag.tag END)) AS categories,
       GROUP_CONCAT(DISTINCT (CASE WHEN tag.category = 'category' THEN tag.tag END)) AS conditions
FROM jds4a_directory d INNER JOIN
     jds4a_tags_resources res
     on d.id = res.resource_id INNER JOIN
     jds4a_tags tag
     on tag.id = res.tag_id
WHERE tag.category IN ('condition', 'category')
GROUP BY d.company_name;

备注：

SELECT 列应与GROUP BY 列一致。不要用无关的列超载。
GROUP BY 应匹配 SELECT.
使用 IN 而不是一堆 OR -- 更易于维护、编写并且不易出错。
对字符串和日期常量使用单引号。不要将它们用于列别名。

Answer 2

您可以尝试以下查询：

SELECT d.company_name AS 'organisation name',
GROUP_CONCAT(DISTINCT tag.tag) AS 'category',
GROUP_CONCAT(DISTINCT tag1.tag) AS 'conditions', d.contact_describtion AS 'description', d.tel, d.tel2, d.mobile, d.email, d.email2, d.web, d.web2, d.address, d.town, d.county, d.post_code AS 'post code', IF(d.state = 1, "published", "unpublished") AS 'status',d.contact_page_notes AS 'contact history', d.last_contacted_date AS 'last contacted', d.last_updated_date AS 'last updated'
FROM jds4a_directory d 
INNER JOIN  jds4a_tags_resources res
on d.id = res.resource_id 
LEFT JOIN jds4a_tags tag
on tag.id = res.tag_id AND tag.category = 'category'
LEFT JOIN jds4a_tags tag1
on tag1.id = res.tag_id AND tag1.category = 'condition' 
GROUP BY res.resource_id

没有尝试过这个查询。但它应该工作。基本上你需要加入 jds4a_tags table 一次条件标签名称

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