我正在尝试加入一个select语句。但是子查询选择返回WAY太多行,这使得它非常慢 - 因为我无法从第一个选择到子查询中获取ID。
错误是:
错误代码:1054。'where子句'中的未知列'ritzau_data.News.id'
如何在第一次选择加入中的select中获取此ID? 我在MSSQL中做了类似的东西 - 运行正常。我也会粘贴正在运行的MSSQL代码。
MySQLCode(不工作):
select News.id as newsid, header as title, content as contents, created as published_time, 2883 as drupalid, isins, categories, NewsTypes.npName from ritzau_data.News,
(
select idNews, group_concat(isin separator ', ') as isins
from ritzau_data.NewsIsin
where idNews = ritzau_data.News.id
group by idNews
) as isins,
(
select idNews, group_concat(distinct Category separator ', ') as categories
from ritzau_data.NewsTags
inner join ritzau_data.TagsCategoriesMap on NewsTags.idTag = TagsCategoriesMap.idTags
inner join ritzau_data.Categories on TagsCategoriesMap.idCategories = Categories.id
where idNews = ritzau_data.News.id
group by idNews
) as categories
left join ritzau_data.NewsTypes on News.idType = NewsTypes.id
inner join ritzau_data.NewsReceivers on News.id = NewsReceivers.idNews
where ritzau_data.News.id > 100 and idReceiver = 3
order by News.id
limit 100;
MSSQLCode(工作):
SELECT TOP 1000 news.id AS newsid,
cast(title as varchar(256)) AS title, cast(contents as text)AS contents, published_time, users.drupalid,
cast (STUFF(
(
SELECT ',' + isin
FROM news_instruments t1
left join instruments t2 on t1.instrument_id = t2.id
where news_id = news.id
FOR XML PATH('')
),1,1,''
) as text) AS isins,
cast(STUFF(
(
SELECT ',' + t2.name
FROM news_categories t1
left join categories t2 on t1.category_id = t2.id
where news_id = news.id
FOR XML PATH('')
),1,1,''
) as text) AS categories
from news
left join users on news.locked_userid = users.id
where news.id > @offsetid
第一个查询 - 它有效,但速度非常慢
select News.id as newsid, header as title, content as contents, created as published_time, 2883 as drupalid, isins, categories, NewsTypes.npName from ritzau_data.News
left join ritzau_data.NewsTypes on News.idType = NewsTypes.id
inner join ritzau_data.NewsReceivers on News.id = NewsReceivers.idNews
select idNews, group_concat(isin separator ', ') as isins
from ritzau_data.NewsIsin
where idNews = News.id
group by idNews
) as isins on News.id = isins.idNews
left join (
select idNews, group_concat(distinct Category separator ', ') as categories
from ritzau_data.NewsTags
inner join ritzau_data.TagsCategoriesMap on NewsTags.idTag = TagsCategoriesMap.idTags
inner join ritzau_data.Categories on TagsCategoriesMap.idCategories = Categories.id
where idNews = News.id
group by idNews
) as categories on News.id = categories.idNews
where News.id > @idoffset and idReceiver = 3
order by News.id
limit 100;
答案 0 :(得分:0)
问题是,新闻表是在不同的模式中,因此您必须在where子句中提供完全限定的名称:
select [...]
from ritzau_data.News
[...]
where ritzau_data.News.id > @idoffset and idReceiver = 3
order by News.id
limit 100;
优雅的方法是给表别名:
select [...]
from ritzau_data.News nw
[...]
where nw.id > @idoffset and idReceiver = 3
order by nw.id
limit 100;
<强>更新强> 你必须从子查询中将子查询中的连接拉到新闻表中:
SELECT News.id AS newsid, header AS title, content AS contents, created AS published_time, 2883 AS drupalid, isins, categories, NewsTypes.npName
FROM ritzau_data.News ritzau_data.News
JOIN
(
SELECT idNews, GROUP_CONCAT(isin SEPARATOR ', ') AS isins
FROM ritzau_data.NewsIsin
GROUP BY idNews
) AS isins
ON isins.idNews = ritzau_data.News.id
JOIN
(
SELECT idNews, GROUP_CONCAT(DISTINCT Category SEPARATOR ', ') AS categories
FROM ritzau_data.NewsTags
INNER JOIN ritzau_data.TagsCategoriesMap ON NewsTags.idTag = TagsCategoriesMap.idTags
INNER JOIN ritzau_data.Categories ON TagsCategoriesMap.idCategories = Categories.id
GROUP BY idNews
) AS categories
ON categories.idNews = ritzau_data.News.id
LEFT JOIN ritzau_data.NewsTypes ON News.idType = NewsTypes.id
INNER JOIN ritzau_data.NewsReceivers ON News.id = NewsReceivers.idNews
WHERE ritzau_data.News.id > 100 AND idReceiver = 3
ORDER BY News.id
LIMIT 100;
<强> UPDATE2:强> 将联接拉到子查询中的新闻:
SELECT News.id AS newsid, header AS title, content AS contents, created AS published_time, 2883 AS drupalid, isins, categories, NewsTypes.npName
FROM ritzau_data.News ritzau_data.News
JOIN
(
SELECT idNews, GROUP_CONCAT(isin SEPARATOR ', ') AS isins
FROM ritzau_data.NewsIsin
JOIN ritzau_data.News ON idNews = ritzau_data.News.id
GROUP BY idNews
) AS isins
JOIN
(
SELECT idNews, GROUP_CONCAT(DISTINCT Category SEPARATOR ', ') AS categories
FROM ritzau_data.NewsTags
INNER JOIN ritzau_data.TagsCategoriesMap ON NewsTags.idTag = TagsCategoriesMap.idTags
INNER JOIN ritzau_data.Categories ON TagsCategoriesMap.idCategories = Categories.id
JOIN ritzau_data.News ON idNews = ritzau_data.News.id
GROUP BY idNews
) AS categories
LEFT JOIN ritzau_data.NewsTypes ON News.idType = NewsTypes.id
INNER JOIN ritzau_data.NewsReceivers ON News.id = NewsReceivers.idNews
WHERE ritzau_data.News.id > 100 AND idReceiver = 3
ORDER BY News.id
LIMIT 100;