detect conflict time using query in vb.net?

问题

This is my query.

("Select Count(*) From table1 where [t1] <= @TimeIn And [t2] >= @TimeOut;", cn)

My problem here is I can't compare other times. For example, if I input 7:00-9:00 then it will be saved as a new time and if I then input 8:00-10:00 it also save in my database how can I solve this I want to prevent the second input time from conflicting with the first?

回答1:

There are three combinations of checks you need to perform when looking for conflicting Time Windows.

1. Is the TimeIn within an existing entry (Time Window)
2. Is the TimeOut within an existing entry
3. Does the combination of TimeIn and TimeOut wholly cover an existing entry

This Sql should cover those options

select
    count(*) from table1 
where
    (
        @timeIn > [T1] AND @timeIn < [T2]
    ) -- TimeIn in existing window
    OR
    (
        @timeOut > [T1] AND @timeOut < [T2]
    ) -- TimeOut in existing window
    OR
    (
        @timeIn < [T1] AND @timeOut > [T2]
    ) -- TimeIn and TimeOut wholly covers existing window

If you get a 0 returned, there are no conflicts

来源：https://stackoverflow.com/questions/56644537/detect-conflict-time-using-query-in-vb-net