Mysql 棘手的SQL选择
我有一个消息表,该表包含以下列:Mysql 棘手的SQL选择,mysql,sql,stored-procedures,join,Mysql,Sql,Stored Procedures,Join,我有一个消息表,该表包含以下列: id | fromUserId | toUserId | sentDate | readDate | message | subject | fromUserDeleted(bit) | toUserDeleted(bit) 现在我需要选择每个转换中的第一条消息,如果它来自或发送给当前用户,则为no mather。更复杂的是,我需要排除当前用户删除的消息,因此如果消息来自当前用户,则fromUserDeleted必须为0如果消息来自其他用户,则toUserDe
id | fromUserId | toUserId | sentDate | readDate | message | subject | fromUserDeleted(bit) | toUserDeleted(bit)
现在我需要选择每个转换中的第一条消息,如果它来自或发送给当前用户,则为no mather。更复杂的是,我需要排除当前用户删除的消息,因此如果消息来自当前用户,则fromUserDeleted必须为0如果消息来自其他用户,则toUserDeleted需要为0
我知道已经有很多关于如何在小组中选择第一篇文章的例子,但这有点复杂。当前用户可能在toUserId或fromUserId中,删除列也是如此
这就是我尝试过的:
SELECT
m1.*,
(SELECT count(*) FROM mail m3 WHERE m3.fromUserId=m1.fromUserId AND m3.toUserId=m1.toUserId AND m3.toUserDeleted = 0) as messageCount,
(SELECT count(*) FROM mail m4 WHERE m4.toUserId=15 AND m4.readDate is null AND m4.toUserDeleted=0) as messagesNotRead
FROM
mail m1
LEFT JOIN mail m2 ON
((m1.fromUserId = m2.fromUserId) and
m2.)
WHERE
m2.id IS NULL AND
(m1.toUserId = 15 OR m1.fromUserId = 15)
ORDER BY
m1.sentDate DESC;
以及:
SELECT
*
FROM
mail m1
WHERE
((m1.fromUserId = 15 AND m1.fromUserDeleted=0) OR (m1.toUserId = 15 AND m1.toUserDeleted=0)) AND
m1.id = (SELECT m2.id FROM mail m2 WHERE m2.fromUserId = 15 OR m2.toUserId = 15 OR m2.fromUserId = m1.fromUserId OR m2.fromUserId = m1.toUserId OR m2.toUserId = m1.fromUserId OR m2.toUserId = m1.toUserId order By m2.sentDate desc limit 0,1)
Order by m1.sentDate DESC
这些都不能满足我的需要。求救
如果需要创建存储过程,也可以
重要提示:这是我的MySQL
编辑1:
请查看此示例:谢谢您的反馈。希望这能满足您的需求:
DECLARE @UserID INT
SELECT @UserID = 15
SELECT *
FROM (
SELECT UserID, ConversationWithUserID, sentDate, readDate, [message], [subject], ROW_NUMBER() OVER (PARTITION BY ConversationWithUserID ORDER BY sentDate ASC) AS MessageOrder
FROM (
SELECT id, fromUserId AS UserID, toUserId AS ConversationWithUserID, sentDate, readDate, [message], [subject]
FROM dbo.mail
WHERE fromUserID = @UserID AND fromUserDeleted = 0
UNION
SELECT id, toUserId AS UserID, fromUserId AS ConversationWithUserID, sentDate, readDate, [message], [subject]
FROM dbo.mail
WHERE toUserId = @UserID AND toUserDeleted = 0
) x
) y
WHERE MessageOrder = 1
ORDER BY y.UserID, y.ConversationWithUserID
在同一列下执行UNPIVOT以获取fromUSerId、toUserId,以便我们可以根据sentDate选择正确的userId
SELECT T.*
FROM
(
SELECT *,
ROW_NUMBER() OVER ( PARTITION BY userVal ORDER BY sentDate DESC) as seq
FROM
(SELECT
*
FROM msg
WHERE (fromUserId = @userID AND fromUserDeleted = 0 )
OR (toUserId = @UserID AND toUserDeleted = 0)
)p
unpivot
( userVal for UserId in ( fromUserId, toUserId)
)as unpvt
) T
WHERE seq =1
你能用测试数据和数据库结构准备一个sql脚本吗?还包括一个理想的结果,你想得到的数据。最好是最小化,包括所有可能的情况。对于查询,只有SendDate起作用,readDate不起作用?@user4035我会试试。@Rajesh readData大多数在select中,但它与select逻辑不匹配。消息的组成是什么。如果您的ID列是自动递增的,并且消息可能是正文,并且在发件人/收件人之间更改,那么标识消息ID序列5的是来自原始消息ID 2的响应。主题是否可以通过Fwd和回复邮件进行更改?这将打破这方面的一个共同点。这将选择当前用户参与且未被他/她删除的所有消息。我需要的是一个列表,上面列出了每个对话中发送给/来自所有用户的最后一封邮件。因此,在当前用户和用户A之间,即使他们有100条消息,我们也应该只返回最新消息。当前用户和用户B也是如此。那么如何确定对话呢?我们是否假设所有来回的消息都是一个对话?是的,一个对话是当前用户使用的所有消息。这比我使用的更高级。我试过使用正确的userId编写脚本,但遇到了语法问题:“PARTITION BY userVal ORDER BY sentDate DESC as seq FROM SELECT”我使用的是MS SQL,你的RDBMS是mysql吗?是的,对不起,它是mysql,我有一个mysql标记,但我当然也应该在我的帖子中提到它。