random worker id in vb.net

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Hi

I have a list of workers with 5 numbered id as primary key.
my application can add new workers to this list but instead of letting the user
decide what id to pick for the new worker, I want the system to pick a random id that is not used.
Is there a way to do that without loading my table each time I need to do it?
it's important to have an id with 5 numbers in it that doesn't start with 0..

any suggestions?

thanx

Posted 1-Apr-12 3:22am

danait25

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2 solutions

Solution 1

Why would it be important what worker is selected as long as the worker is not in use. Could you simply use for example a FIFO list for workers not in use and pick the first one.

Posted 1-Apr-12 3:27am

Wendelius

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danait25 2-Apr-12 1:22am

I thought about it but I have already numbers that start with [988##] etc.. so I don't want my numbers to run too fast (although it's probably Hundreds of ids before it's run out..)

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Shahin Khorshidnia · Accepted Answer · 2012-04-01T12:44:00

Let's suppose that the table of Workers is not changing during runtime:
For example you have a collection of Workers

VB

Dim WorkerList As New List(Of Worker)()

Then the application needs to Select all Workers from database once at starting.
Now, you need a field:

VB

Private random As New Random()

And a method:

VB

Public Function GetAWorker(workerList As List(Of Worker)) As Worker
    Dim myWorker As Worker = workerList(random.[Next](0, workerList.Count()))

    workerList.Remove(myWorker)

    Return myWorker
End Function

You must pass the WorkerList to this method and get a random worker.
It removes the selected worker from the the WorkerList because it is Reference Type.
So the application can add unused worker to the list without any interfering.

Note:
If the table of workers may be modified during runtime, then have to check the database, and add new workers to WorkerList before than calling the method.