我在页面底部有一个工作选择。正如你所看到的,它有53行,在我看来,这太过分了。有人告诉我,有一个' if'在MySQL中可用的条件,但我无法使其工作。工作选择联合4选择,因为在每个选择中,我需要加入另一个表。是否可以根据内容加入表格?
SELECT *
FROM (
SELECT m.`identificator` , ml.id AS link_id, ml.parent, ml.type,
ml.destination, ml.disabled, ml.order, mld.`name` AS link_name,
mld.`alt` , mld.`title` , cpd.`slug`
FROM `wf_menu` m
LEFT JOIN `wf_menu_link` ml ON m.`id` = ml.`menu_id`
LEFT JOIN `wf_menu_link_desc` mld ON ml.`id` = mld.`link_id`
LEFT JOIN `wf_cms_post_desc` cpd ON ml.destination = cpd.post_id
WHERE mld.`lang_id` =1
AND mld.`lang_id` = cpd.`lang_id`
AND (ml.`type` = 'page'
OR ml.`type` = 'article')
UNION
SELECT m.`identificator` , ml.id AS link_id, ml.parent, ml.type,
ml.destination, ml.disabled, ml.order, mld.`name` AS link_name,
mld.`alt` , mld.`title` , cpd.`slug`
FROM `wf_menu` m
LEFT JOIN `wf_menu_link` ml ON m.`id` = ml.`menu_id`
LEFT JOIN `wf_menu_link_desc` mld ON ml.`id` = mld.`link_id`
LEFT JOIN `wf_cms_category_desc` cpd ON ml.destination = cpd.category_id
WHERE mld.`lang_id` =1
AND mld.`lang_id` = cpd.`lang_id`
AND ml.`type` = 'cmscat'
UNION
SELECT m.`identificator` , ml.id AS link_id, ml.parent, ml.type,
ml.destination, ml.disabled, ml.order, mld.`name` AS link_name,
mld.`alt` , mld.`title` , spd.`slug`
FROM `wf_menu` m
LEFT JOIN `wf_menu_link` ml ON m.`id` = ml.`menu_id`
LEFT JOIN `wf_menu_link_desc` mld ON ml.`id` = mld.`link_id`
LEFT JOIN `wf_shop_category_desc` spd ON ml.destination = spd.category_id
WHERE mld.`lang_id` =1
AND mld.`lang_id` = spd.`lang_id`
AND ml.`type` = 'shopcat'
UNION
SELECT m.`identificator` , ml.id AS link_id, ml.parent, ml.type,
ml.destination, ml.disabled, ml.order, mld.`name` AS link_name,
mld.`alt` , mld.`title` , 'link' as slug
FROM `wf_menu` m
LEFT JOIN `wf_menu_link` ml ON m.`id` = ml.`menu_id`
LEFT JOIN `wf_menu_link_desc` mld ON ml.`id` = mld.`link_id`
WHERE mld.`lang_id` =1
AND ml.`type` = 'link'
) a
ORDER BY `order` DESC
答案 0 :(得分:0)
我认为您需要使用动态SQL。我的意思是,将结束SQL构建为临时变量并执行它:
set @query = (SELECT ...);
PREPARE st FROM @query;
EXECUTE st;
你的第一个案例可能是:
SET @query= (SELECT CONCAT(GROUP_CONCAT(CONCAT('SELECT m.`identificator` , ml.id AS link_id, ml.parent, ml.type,
ml.destination, ml.disabled, ml.order, mld.`name` AS link_name,
mld.`alt` , mld.`title` , cpd.`slug` FROM `wf_menu` m LEFT JOIN `wf_menu_link` ml ON m.`id` = ml.`menu_id` ',
CASE WHEN TTYPES.type='article' THEN
CONCAT('LEFT JOIN `wf_menu_link_desc` mld ON ml.`id` = mld.`link_id` LEFT JOIN `wf_cms_post_desc` cpd ON ml.destination = cpd.post_id WHERE mld.`lang_id` =1 AND mld.`lang_id` = cpd.`lang_id` AND (ml.`type` = \'page\' OR ml.`type` = \'',TTYPES.type,'\')')
END )
SEPARATOR ' UNION '), ' SELECT NULL FROM wf_menu_link WHERE 1=2') FROM (SELECT DISTINCT wf_menu_link.`type` FROM wf_menu_link) TTYPES);
(您可以完成剩余案例)
运行该查询将使用生成的查询填充@query
变量。生成的查询应与您在问题中发布的查询相同。然后你可以在这个答案中看到上面的内容。
这是一个示例/想法,您必须完成它和/或检查它是否适用于您的模型。
答案 1 :(得分:0)
您可以只使用每个左连接执行单个查询,并使用IF语句对生成的“slug”列进行排序。但是,这取决于您想要输出的内容,以及其他表上是否有多个匹配的行。
这样的事情: -
SELECT m.identificator , ml.id AS link_id, ml.parent, ml.type,
ml.destination, ml.disabled, ml.order, mld.name AS link_name,
mld.alt , mld.title , cpd.slug
FROM wf_menu m
LEFT JOIN wf_menu_link ml ON m.id = ml.menu_id
LEFT JOIN wf_menu_link_desc mld ON ml.id = mld.link_id
LEFT JOIN wf_cms_post_desc cpd ON ml.destination = cpd.post_id AND (ml.type = 'page' OR ml.type = 'article')
LEFT JOIN wf_cms_category_desc cpd ON ml.destination = cpd.category_id AND ml.type = 'cmscat' AND mld.lang_id = cpd.lang_id
LEFT JOIN wf_shop_category_desc spd ON ml.destination = spd.category_id AND ml.type = 'shopcat' AND mld.lang_id = spd.lang_id
WHERE mld.lang_id =1
AND mld.lang_id = cpd.lang_id