Question

我有一个包含以下字段的MySQL表：

名称
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”表的方法，以查看表中的时间范围是否有任何重叠。如果来自10:00-11:00的事件和来自10:30-11:30的事件，我希望收到有关时间重叠的警告。

没什么好看的，我想知道是否存在重叠。

我将使用PHP来执行此操作。

Answer 1

这是一个查询模式，多年前我找到了答案：

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

要查找“任何重叠”，请将时间范围的相反两端相互比较。这是我必须得到笔和纸张并绘制相邻范围以实现边缘情况归结为此比较。

如果要防止任何行重叠，请将此查询的变体放在触发器中：

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天数的两个时间范围是否重叠，这也适用于计划在午夜之前开始并在之后结束的情况，例如＆＃34; 17：00：00-03：00：00＆＃ 34;和＆＃34; 14：00：00-01：00：00＆＃34;应该重叠，所以我修改了solution by Bohemian

您使用此功能如下

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

或者像你这样的情况

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

这是功能定义

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，可能会受到数据库时区设置的影响，想象第二天有DST更改。

如果您的数据库使用UTC时区（应该如此），那么您可以使用此

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

检查表格的时间重叠？

4 个答案: