SQL数据透视和计算以字符串形式存储的日期之间的差异-MySQL
我有两张桌子。第一个称为SQL数据透视和计算以字符串形式存储的日期之间的差异-MySQL,mysql,sql,pivot,mariadb,Mysql,Sql,Pivot,Mariadb,我有两张桌子。第一个称为posts，第二个称为postmeta。（如果有人注意到，我正在使用Wordpress db，这对于这项任务来说并不重要） posts表如下所示（为此缩短） postETA表如下所示。日期格式为d.m.Y.G:i:s meta_id | post_id | meta_key | meta_value ------------------------------------------ 1 | 1 | from | 1.1.2017. 10:
postspostmetapostspostETAmeta_id | post_id | meta_key | meta_value
------------------------------------------
1 | 1 | from | 1.1.2017. 10:00:00
2 | 1 | to | 1.1.2017. 16:00:00
3 | 2 | from | 2.1.2017. 12:00:00
4 | 2 | to | 2.1.2017. 15:00:00
IDpost\u IDdate\u difffromtometa_keyVARCHARmeta_valueLONGTEXTID | title | from | to | date_diff
------------------------------------------------------------------
1 | 1 | 1.1.2017. 10:00:00 | 1.1.2017. 16:00:00 | 6
2 | 1 | 2.1.2017. 12:00:00 | 2.1.2017. 15:00:00 | 3
SELECT posts.ID, posts.post_title, postmeta.meta_key, postmeta.meta_value
FROM posts
INNER JOIN postmeta
ON posts.ID = postmeta.post_id
WHERE post_status = 'publish'
AND post_type = 'hours'
AND (postmeta.meta_key = 'from' OR postmeta.meta_key = 'to');
非常感谢。：） 您可以在POSTETA上使用自连接来获取两个分离的列 使用str_to_date转换日期中的字符串 对保留字（例如：from）使用适当的backtics 和TIMESTAMPDIFF，用于获取diff的小时数
SELECT
posts.ID
, posts.post_title
, str_to_date(table_from.meta_value, '%d.%m.%Y. %H:%i:%s') as `from`
, str_to_date(table_to.meta_value, '%d.%m.%Y. %H:%i:%s' ) as `to`
, TIMESTAMPDIFF(HOUR, str_to_date(table_from.meta_value, '%d.%m.%Y. %H:%i:%s') ,
str_to_date(table_to.meta_value, '%d.%m.%Y. %H:%i:%s' )) as diff
FROM posts
INNER JOIN postmeta table_from ON posts.ID = table_from.post_id and table_from.meta_key ='from'
inner join postmeta table_to ON posts.ID = table_to.post_id and table_to.meta_key ='to'
WHERE post_status = 'publish'
AND post_type = 'hours'
timestampdiff（分钟、开始日期、结束日期）/60作为diff，我希望它能有所帮助
SELECT
p.id,
p.post_title,
postmeta_temp.from,
postmeta_temp.to,
postmeta_temp.date_diff
FROM posts p
INNER JOIN (SELECT postmeta_from.post_id
AS post_id,
postmeta_from.meta_key
AS from,
postmeta_to.meta_key
AS to,
Date_diff(postmeta_to.meta_value,
postmeta_from.meta_value)
AS date_diff
FROM postmeta postmeta_from
INNER JOIN postmeta postmeta_to
ON postmeta_from.post_id = postmeta_to.post_id
AND postmeta_from.meta_key = 'from'
AND postmeta_to.meta_key = 'to') AS
postmeta_temp
ON p.id = postmeta_temp.post_id
我把最后一部分留给读者作为一个（简单的）练习。对于每一个ID，我下次会用相同的ID和下一个日期检查
select pm.post_id as ID, pm.post_id as title, pm.metavalue as from,
(select x.metavalue from postmeta x where x.enter code herepost_id = pm.post_id and not x.meta_key = 'from')
as to ,
(select cast(x.metavalue as timestamp) - cast(pm.metavalue as timestamp) from postmeta x
where x.post_id = pm.post_id and not x.meta_key = 'from') as date_diff from
postmeta pm where pm.meta_key = 'from';
id | title | from | to | date_diff
----+-------+--------------------+--------------------+-----------
1 | 1 | 1.1.2017. 10:00:00 | 1.1.2017. 16:00:00 | 06:00:00
2 | 2 | 2.1.2017. 12:00:00 | 2.1.2017. 15:00:00 | 03:00:00
感谢您的回复，我尝试了代码，但是from、to和diff只有空值。在测试代码时，我注意到str_to_date返回空值，所以这可能是原因，但仍然不起作用，但是，它非常接近。可能是日期格式。。。年复一年地漏掉一点。。答案用点更新。如果使用24小时，格式必须为H而不是H。。回答UpdateEdit起作用，TIMESTAMPDIFF是否可以以小数形式显示小时，例如1.5小时，因为目前它只显示整小时我认为你的数据集出错了。什么是post_id=3！？！哦，对不起，错别字，是2:）草莓，谢谢你的回答，太棒了，不幸的是我只能把一个答案当作正确答案。你努力回答，所以我能做的最小的事情就是给它投票；）谢谢：）
DROP TABLE IF EXISTS posts;
CREATE TABLE posts
(id INT NOT NULL AUTO_INCREMENT PRIMARY KEY
,post_title VARCHAR(12) NOT NULL
,post_status VARCHAR(12) NOT NULL
,post_type VARCHAR(12) NOT NULL
);
INSERT INTO posts VALUES
(1,'One','publish','hours'),
(2,'Two','publish','hours');
DROP TABLE IF EXISTS postmeta;
CREATE TABLE postmeta
(meta_id INT NOT NULL AUTO_INCREMENT PRIMARY KEY
,post_id INT NOT NULL
,meta_key VARCHAR(12) NOT NULL
,meta_value VARCHAR(20) NOT NULL
);
INSERT INTO postmeta VALUES
(1,1,'from','1.1.2017. 10:00:00'),
(2,1,'to' ,'1.1.2017. 16:00:00'),
(3,2,'from','2.1.2017. 12:00:00'),
(4,2,'to' ,'2.1.2017. 15:00:00');
-- Date format is d.m.Y. H:i:s.
SELECT post_id
, MAX(CASE WHEN meta_key = 'from' THEN STR_TO_DATE(meta_value,'%d.%m.%Y. %H:%i:%s') END) `from`
, MAX(CASE WHEN meta_key = 'to' THEN STR_TO_DATE(meta_value,'%d.%m.%Y. %H:%i:%s') END) `to`
, TIMEDIFF(
MAX(CASE WHEN meta_key = 'to' THEN STR_TO_DATE(meta_value,'%d.%m.%Y. %H:%i:%s') END)
, MAX(CASE WHEN meta_key = 'from' THEN STR_TO_DATE(meta_value,'%d.%m.%Y. %H:%i:%s') END)
) date_diff
FROM postmeta
GROUP
BY post_id;
+---------+---------------------+---------------------+-----------+
| post_id | from | to | date_diff |
+---------+---------------------+---------------------+-----------+
| 1 | 2017-01-01 10:00:00 | 2017-01-01 16:00:00 | 06:00:00 |
| 2 | 2017-01-02 12:00:00 | 2017-01-02 15:00:00 | 03:00:00 |
+---------+---------------------+---------------------+-----------+
select pm.post_id as ID, pm.post_id as title, pm.metavalue as from,
(select x.metavalue from postmeta x where x.enter code herepost_id = pm.post_id and not x.meta_key = 'from')
as to ,
(select cast(x.metavalue as timestamp) - cast(pm.metavalue as timestamp) from postmeta x
where x.post_id = pm.post_id and not x.meta_key = 'from') as date_diff from
postmeta pm where pm.meta_key = 'from';
id | title | from | to | date_diff
----+-------+--------------------+--------------------+-----------
1 | 1 | 1.1.2017. 10:00:00 | 1.1.2017. 16:00:00 | 06:00:00
2 | 2 | 2.1.2017. 12:00:00 | 2.1.2017. 15:00:00 | 03:00:00