MySQL比较同一表上的两个值
我试图比较同一个表中的两个值,并检查是否存在差异。 目前,我在cms_statistics_pages表中有1485条记录,但当以下查询:MySQL比较同一表上的两个值,mysql,compare,Mysql,Compare,我试图比较同一个表中的两个值,并检查是否存在差异。 目前,我在cms_statistics_pages表中有1485条记录,但当以下查询: SELECT cp.identifier, COUNT(csp1.statID) AS hits, COUNT(csp2.statID) AS hits_yesterday, IF(COUNT(csp1.statID)>COUNT(csp2.statID),1,0) AS growth FROM cms_pages cp
SELECT
cp.identifier,
COUNT(csp1.statID) AS hits,
COUNT(csp2.statID) AS hits_yesterday,
IF(COUNT(csp1.statID)>COUNT(csp2.statID),1,0) AS growth
FROM cms_pages cp
LEFT JOIN cms_statistics_pages csp1
ON csp1.pageID = cp.pageID
AND DATE(csp1.datetime) = '2012-07-20'
LEFT JOIN cms_statistics_pages csp2
ON csp2.pageID = cp.pageID
AND DATE(csp2.datetime) = '2012-07-19'
GROUP BY cp.identifier
…被解雇后,我得到以下结果:
identifier hits hits_yesterday growth
index 13395 13395 0
siden-er-under-opdatering 638 638 0
vores-historie 0 3 0
这对我来说是不正确的。如果我改变:
AND DATE(csp1.datetime) = '2012-07-20'
到不匹配任何记录的日期
AND DATE(csp1.datetime) = '2012-07-21'
现在,我的结果如下所示:
identifier hits hits_yesterday growth
index 0 141 0
siden-er-under-opdatering 0 29 0
vores-historie 0 3 0
现在点击是正确的,所以我想知道当两个连接都包含一些数据时,查询是否会多次统计记录
来自cms_页面的示例数据:
pageID sectionID templateID identifier default title exclude_title
1 1 1 index 1 Welcome to SiteTech Framework 2012
pageID sectionID templateID标识符默认标题排除\u标题
1索引1欢迎使用SiteTech Framework 2012
cms_统计_页面中的示例数据:
statID frontend backend pageID sectionID panel datetime
1 0 1 34 6 admin 2012-07-17 12:34:14
statID前端后端pageID sectionID面板datetime
101346管理员2012-07-1712:34:14
我遇到了这篇文章,它提供了一种更高级的跨多个表计数的方法,这可能会阻止查询对同一条记录进行多次计数。我自己还没有尝试过-我发现这篇文章提供了一种更高级的跨多个表计数的方法,这可能会阻止查询对同一条记录进行多次计数。我自己还没有尝试过-所以我对查询做了一些修改,找到了一个包括左连接和子查询的解决方案。我的查询现在看起来像:
SELECT
cp.identifier,
now.hits AS hits,
yd.hits AS hits_yesterday,
IF(now.hits>yd.hits,1,0) AS growth
FROM cms_pages AS cp
LEFT JOIN
(
SELECT
pageID,
COUNT(pageID) AS hits
FROM cms_statistics_pages
WHERE DATE(datetime) = '2012-07-20'
GROUP BY pageID
) now
ON now.pageID = cp.pageID
LEFT JOIN
(
SELECT pageID,
COUNT(pageID) AS hits
FROM cms_statistics_pages
WHERE DATE(datetime) = '2012-07-19'
GROUP BY pageID
) yd
ON yd.pageID = cp.pageID
这给了我这个正确的结果!:
identifier hits hits_yesterday growth
index 95 141 0
siden-er-under-opdatering 22 29 0
vores-historie NULL 3 0
所以我对查询做了一些修改,找到了一个包括左连接和子查询的解决方案。我的查询现在看起来像:
SELECT
cp.identifier,
now.hits AS hits,
yd.hits AS hits_yesterday,
IF(now.hits>yd.hits,1,0) AS growth
FROM cms_pages AS cp
LEFT JOIN
(
SELECT
pageID,
COUNT(pageID) AS hits
FROM cms_statistics_pages
WHERE DATE(datetime) = '2012-07-20'
GROUP BY pageID
) now
ON now.pageID = cp.pageID
LEFT JOIN
(
SELECT pageID,
COUNT(pageID) AS hits
FROM cms_statistics_pages
WHERE DATE(datetime) = '2012-07-19'
GROUP BY pageID
) yd
ON yd.pageID = cp.pageID
这给了我这个正确的结果!:
identifier hits hits_yesterday growth
index 95 141 0
siden-er-under-opdatering 22 29 0
vores-historie NULL 3 0