Question

使用SQL 2005.我有三个表：会议，联系人和Meeting_Contacts。

会议表包含以下字段：Meeting_ID，Meeting_Name，Date_Start，Location

联系人有：Contact_ID，First_Name，Last_Name，Missed_Three_Days

Meeting_Contacts：Meeting_ID，Contact_ID

如果个人错过连续三天（周末除外），我需要更新“Missed_Three_Days”字段。

e.g。如果他错过星期五，星期一和星期二，“Missed_Three_Days字段将在星期二更新。

这是我到目前为止的地方......我被卡在哪里声明。

 update contacts set missed_three_days = 'Missed 3 Days' 
 where ID not in 

 (select contact_ID from MEETINGS_CONTACTS mc
  Join meetings m
 on m.id = mc.meeting_id
 join contacts c
 on c.id = mc.contact_ID
 where m.date_start  ???)

我有一种感觉很明显......但我的思绪并没有指向今天的方向。

感谢您的帮助。

Answer 1

从臀部拍摄你可以创建一个功能，测试每个错过的会议，以便错过第二次，然后第三次会议来自同一个人。像这样：

CREATE FUNCTION MissedThree
(
@pContact_ID int,
@pKeyDate Date
)
RETURNS Bit
AS
BEGIN

DECLARE @pReturnValue Bit = 0  /** FALSE UNTIL PROVEN OTHERWISE */

/** DID CONTACT MISS THIS MEETING? */
IF NOT Exists
    (SELECT Meetings.Meeting_ID FROM 
    Meeting_Contacts INNER JOIN Meetings 
    ON Meetings.Meeting_ID = Meeting_Contacts.Meeting_ID
    WHERE Contact_ID = @pContact_ID AND Meetings.Date_Start = @pKeyDate)
BEGIN

    /** CHECK TO SEE IF NEXT WAS ALSO MISSED */

    DECLARE @pMeetingTwo Date       

    SELECT @pMeetingTwo = MAX(Date_Start) 
                FROM Meetings WHERE Date_Start > @pKeyDate;

    IF NOT Exists 
        (SELECT Meetings.Meeting_ID FROM 
        Meeting_Contacts INNER JOIN Meetings 
        ON Meetings.Meeting_ID = Meeting_Contacts.Meeting_ID
        WHERE Contact_ID = @pContact_ID AND Meetings.Date_Start = @pMeetingTwo)
    BEGIN

       /** CHECKT TO SEE IF A THIRD CONSECUTIVE WAS MISSED */         

       DECLARE @pMeetingThree Date

       SELECT @pMeetingThree = MAX(Date_Start) 
                   FROM Meetings WHERE Date_Start > @pMeetingTwo;

       IF NOT Exists 
               (SELECT Meetings.Meeting_ID FROM 
               Meeting_Contacts INNER JOIN Meetings 
               ON Meetings.Meeting_ID = Meeting_Contacts.Meeting_ID
               WHERE Contact_ID = @pContact_ID AND Meetings.Date_Start = @pMeetingThree)
        BEGIN         
           SET @pReturnValue = 1
        END
    END     

END 

RETURN @pReturnValue;

END

从那里你只需要运行一个查询来识别罪魁祸首。

SELECT Contact_ID, Start_Date FROM 
    Meeting_Contacts INNER JOIN Meetings 
        ON Meetings.Meeting_ID = Meeting_Contacts.Meeting_ID 
    WHERE dbo.MissedThree(Contact_ID, Start_Date) = 1

这里的好处是，它使用会议桌来确定会议的结果性质......而不是可能出现诸如周末，假日，非工作日等问题的日历。

我确信我能想出一个更优雅的解决方案，效率更高，但你必须付出比SO更多的钱:)。也许这会让你的创意果汁至少流淌。很多人都试图避免瘟疫之类的功能。

另外，你没有提到Sql版本，所以请注意，如果它不是2008，则需要为DateTime交换Date数据类型。

Answer 2

我认为这样的事情可能会满足你的需求。

   --select contacts who attended less than 3 of the last 3 meetings
    SELECT 
          contacts.contact_id,
          COUNT(meeting_contacts.meeting_id) as AttendedMeetings
    FROM contacts
    LEFT OUTER JOIN
    (     SELECT TOP 3 
               meetings.meeting_id
           FROM meetings
           ORDER BY meetings.date
    ) as Last3Meetings --the last 3 meetings and their attendees, regardless of when the meeting happened
      LEFT OUTER JOIN meeting_contacts
           ON meetings.meeting_id = meeting_contacts.meeting_id
           AND contacts.contact_id = meeting_contacts.contact_id
HAVING COUNT(contacts.meeting_id) < 3

快乐的编码！

更新连续3天缺席的个人

2 个答案: