SQL Server 2008 中的唯一日期范围字段 [英] Unique date range fields in SQL Server 2008

问题描述

我有一个表，其中包含两个名为 StartTime 和 EndTime 的字段.两者都是 TIME 字段.

I have a table that consists of, among other things, two fields named StartTime and EndTime. Both are TIME fields.

我想添加一个约束，以防止插入与预先存在的时间范围重叠的任何记录.例如.如果 StartTime = 5:00, EndTime = 10:00 的记录已经存在，我希望 StartTime = 6:00, EndTime = 9:00 的插入由于重叠而失败.

I want to add a constraint preventing the insertion of any records that overlap with preexisting time ranges. E.g. if a record already exists with StartTime = 5:00, EndTime = 10:00, I would want an insert with StartTime = 6:00, EndTime = 9:00 to fail due to the overlap.

有没有办法做到这一点，不管有没有触发器?

Is there any way to accomplish this, with or without triggers?

推荐答案

下面的触发器应该可以工作 - 也可以使用检查约束来做到这一点，但是 这篇文章有点让我头疼.

The trigger below should work - it is also possible to do this with check contraints, but the logic shown in this post kind of hurts my head.

CREATE TRIGGER [dbo].[DateRangeTrigger]
   ON  [dbo].[TargetTable]
   FOR INSERT, UPDATE
AS 
BEGIN

IF EXISTS (SELECT t.starttime, t.endtime FROM TargetTable t
        Join inserted i
        On (i.starttime > t.starttime AND i.starttime < t.endtime AND i.UniqueId <> t.UniqueId) 
           OR (i.endtime < t.endtime AND i.endtime > t.starttime AND i.UniqueId <> t.UniqueId)
           OR (i.starttime < t.starttime AND i.endtime > t.endtime AND i.UniqueId <> t.UniqueId)
        )
BEGIN
    RAISERROR ('Inserted date was within invalid range', 16, 1)
    IF (@@TRANCOUNT>0)
        ROLLBACK
END


END

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