[英]How to condition SQL WHERE
我想确定何时要GROUP_CONCAT我的结果。 我不知道如何区分“类别”和“条件”结果的方式。
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d.email2, d.web, d.web2, d.address, d.town, d.county, d.post_code AS 'post code', IF(d.state = 1, "published", "unpublished") AS 'status',d.contact_page_notes AS 'contact history', d.last_contacted_date AS 'last contacted', d.last_updated_date AS 'last updated'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
我要实现的是仅在类别下显示类别标签,而在条件下仅显示条件标签
用case
。 我认为您还会返回太多列,
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;
笔记:
SELECT
列应与GROUP BY
列一致。 不要让多余的列过载。 GROUP BY
应该匹配SELECT
未聚合的键/表达式。 IN
,而不是一堆的OR
秒-易于维护,写,不容易出错。 您可以在下面的查询中尝试:
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d.email2, d.web, d.web2, d.address, d.town, d.county, d.post_code AS 'post code', IF(d.state = 1, "published", "unpublished") AS 'status',d.contact_page_notes AS 'contact history', d.last_contacted_date AS 'last contacted', d.last_updated_date AS 'last updated'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
尚未尝试此查询。 但它应该起作用。 基本上,您需要使用条件标签名称再加入jds4a_tags表一次
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