Request

[carrielucky]

if I got 10 pc, users are click save button to save the data into database at the same time
Can I know which data will be save into database first?
It is depends on what to save that record into database first?

[PadexArt]

if I got 10 pc, users are click save button to save the data into database at the same time
Can I know which data will be save into database first?
It is depends on what to save that record into database first?

You cannot tell who will get to write first and in most cases you don't care to know either. Besides, allowing multiple users to write data indiscriminately will most likely corrupt your data.

When working with databases you should employ locks and transactions to manage concurrent data access.

The lock and transaction concepts can be applied to data that is not organized in a database but depending on the API you use to access that data it can be much more complicated.

[GCDEF]

A good database ought to handle concurrent users without anything getting corrupted. I don't know of any to guaranty who gets processed first if they all write at the same time.