Talk about how to ensure that only one user is editing a certain record when processing WEB data updates?

missun

I did not use a timestamp, that is to judge when submitting the data, I used to add a time field to the table that needs to be uniquely updated, this field is used to record the time when the record was last updated, such as the record to be updated now The value of the time field is 2017-01-01 1:00:00, and the predefined timeout interval for the operation is 20 minutes. If the operation time does not exceed the defined timeout interval when compared with the time field in the record, then someone is considered The record, otherwise it is considered that the timeout record can be edited.
Tell me how do you do this kind of operation?

苹果小刀

It seems impossible to control on the page, but the database has a mechanism to ensure concurrency! I do not know what the landlord intends to do?
If you want to guarantee the situation you mentioned, I personally think that you can add a marker column to the database. If it is true, make sure it is editable, otherwise it is not

missun

to苹果小刀:
 There is no need to consider this problem for the addition and deletion of data, mainly to update the data, because it is necessary to ensure that only one person is editing a certain record when editing. Therefore, I use time. If you use a tag column, then the client is abnormal The record will no longer be editable.

yfacmilan

An application object can be set to record the record being edited. When any user edits a record, it is necessary to determine whether the record has an id in the application. Delete the id of the record from the application

dydcool

You can start from the database to consider this issue, such as the use of table locks, record identification, and so on.

养狗的上帝

Create an additional table to record all the edited records. When others open the edited records, they will be tested first, and if they exist, they will be prompted to lock.

It seems not very good to use the database directly ~~ I do n’t know how to control

wangweipeng

Not feasible,

The most basic approach is to use transaction processing

lighter123

Keep following ...

江南小色

This situation is bound to exist and can only be dealt with, not guaranteed.
You can only use transactions. Simply judging in the database will not work. Dirty reading and repeated reading cannot be solved.

rcloud

Pessimistic locking solution

-We can achieve pessimistic locking with only minor changes to the code above.

declare @CardNo varchar (20)
Begin Tran

       -Choose an unused card
        select top 1 @ CardNo = F_CardNo
        from Card with (UPDLOCK) where F_Flag = 0
        
        -Delay 50 seconds to simulate concurrent access.
        waitfor delay '000: 00: 50'

       -Register the card you just selected.

        update Card
        set F_Name = user,
            F_Time = getdate (),
            F_Flag = 1
        where F_CardNo = @ CardNo

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