检查表格的时间重叠？

Question

我有一个包含以下字段的 MySQL 表：

• 姓名
• 开始时间
• 结束时间

starttime 和 endtime 是 MySQL TIME 字段（不是 DATETIME）。我需要一种定期“扫描”表格的方法，以查看表格内的时间范围是否有任何重叠。如果有来自10:00-11:00 的事件和来自10:30-11:30 的另一个事件，我希望收到时间重叠存在的警报。

没什么特别的，我只想知道是否存在重叠。

我将使用 PHP 来执行此操作。

Answer 1

这是我多年前找到答案的查询模式：

SELECT *
FROM mytable a
JOIN mytable b on a.starttime <= b.endtime
    and a.endtime >= b.starttime
    and a.name != b.name; -- ideally, this would compare a "key" column, eg id

要找到“任何重叠”，您需要将时间范围的相反端相互比较。这是我必须拿出笔和纸并画出相邻范围才能意识到边缘情况归结为这种比较的东西。

---

如果您想防止任何行重叠，请将此查询的变体放入触发器中：

create trigger mytable_no_overlap
before insert on mytable
for each row
begin
  if exists (select * from mytable
             where starttime <= new.endtime
             and endtime >= new.starttime) then
    signal sqlstate '45000' SET MESSAGE_TEXT = 'Overlaps with existing data';
  end if;
end;

Answer 2

我想要一个通用函数来检查日期的两个时间范围是否重叠，这也适用于时间表在午夜之前开始并在午夜之后结束的情况，例如“17:00:00-03:00:00”和“14 :00:00-01:00:00" 应该重叠，所以我修改了solution by Bohemian

你使用这个函数如下

SELECT func_time_overlap("17:00:00","03:00:00", "14:00:00","01:00:00")

或者在你的情况下是这样的

SELECT *
FROM mytable a
JOIN mytable b ON (
    a.name != b.name 
    AND func_time_overlap(a.starttime, a.endtime, b.starttime, b.endtime)
);

这是函数定义

CREATE FUNCTION `func_time_overlap`(a_start TIME, a_end TIME, b_start TIME, b_end TIME) 
RETURNS tinyint(1) 
DETERMINISTIC
BEGIN

-- there are only two cases when they don't overlap, but a lot of possible cases where they do overlap

-- There are two time formats, one is an interval of time that can go over 24 hours, the other is a daily time format that never goes above 24 hours
-- by default mysql uses TIME as an interval
-- this converts a TIME interval into a date time format

-- I'm not using `TIME(CAST(a_start AS DATETIME));` to convert the time interval to a time
-- because it uses the current day by default and might get affected by the timezone settings of the database, 
-- just imagine the next day having the DST change.
-- although the CAST should work fine if you use UTC

IF a_start >= 24 THEN 
    SET a_start = TIME(CONCAT(MOD(HOUR(a_start), 24),':',MINUTE(a_start),':',SECOND(a_start))); 
END IF;

IF b_start >= 24 THEN 
    SET b_start = TIME(CONCAT(MOD(HOUR(b_start), 24),':',MINUTE(b_start),':',SECOND(b_start))); 
END IF;

IF a_end > 24 THEN 
    SET a_end = TIME(CONCAT(MOD(HOUR(a_end), 24),':',MINUTE(a_end),':',SECOND(a_end))); 
END IF;

IF b_end > 24 THEN 
    SET b_end = TIME(CONCAT(MOD(HOUR(b_end), 24),':',MINUTE(b_end),':',SECOND(b_end))); 
END IF;


-- if the time range passes the midnight mark, then add 24 hours to the time
IF a_start >= a_end THEN 
    SET a_end = a_end + INTERVAL 24 HOUR; 
END IF;

IF b_start >= b_end THEN 
    SET b_end = b_end + INTERVAL 24 HOUR; 
END IF;

RETURN a_start < b_end AND a_end > b_start;


END

我没有使用TIME(CAST(a_start AS DATETIME)); 将时间间隔转换为时间，因为它默认使用当前日期，并且可能会受到数据库时区设置的影响，想象一下第二天 DST 更改。

如果您的数据库使用 UTC 时区（应该如此），那么您可以使用它

IF a_start >= 24 THEN 
    SET a_start = TIME(CAST(a_start AS DATETIME)); 
END IF;

IF b_start >= 24 THEN 
    SET b_start = TIME(CAST(b_start AS DATETIME)); 
END IF;

IF a_end > 24 THEN 
    SET a_end = TIME(CAST(a_end AS DATETIME));
END IF;

IF b_end > 24 THEN 
    SET b_end = TIME(CAST(b_end AS DATETIME));
END IF;

Answer 3

试试这个：

declare @tempTbl table(RecID)

    insert into @tempTbl
    Select RecID
    from 
    (
    Select t.RecID from Table1 t,Table1 t1
    where t.StartTime between t1.StartTime AND t1.EndTime
    AND t.RecID <> t1.RecID  

    )

Answer 4

试试这个，它对我有用

SELECT * from Shedulles a 
where exists 
( select 1 from Shedulles b 
    where 
    a.ShedulleId != b.ShedulleId 
    and ( a.DateFrom between b.DateFrom and b.DateTo 
    or a.DateTo between b.DateFrom and b.DateTo 
    or b.DateFrom between a.DateFrom and a.DateTo ) 
    and a.DateFrom != b.DateTo 
    and b.DateFrom != a.DateTo 
);

或者这个

SELECT DISTINCT a.* FROM Shedulles a
JOIN Shedulles b 
    ON 
    a.ShedulleId != b.ShedulleId 
    and ( a.DateFrom between b.DateFrom and b.DateTo 
    or a.DateTo between b.DateFrom and b.DateTo 
    or b.DateFrom between a.DateFrom and a.DateTo ) 
    and a.DateFrom != b.DateTo 
    and b.DateFrom != a.DateTo