Skip to main content
PreetiGupta15-Moonstone
15-Moonstone
July 6, 2016
Question

system generated number for primary key in the datatable

  • July 6, 2016
  • 6 replies
  • 5595 views

I want to generate sequential number for my number field in the data table. Is this possible?

thanks.

      6 replies

      ttielebein5-Regular Member
      5-Regular Member
      July 6, 2016

      Hello,

      I have done this before by creating a property on the datatable which I just increment by one each time I successfully add a new entry. The property serves to function just like a nextVal would within an actual database.

      Hope this helps!

      Tori

        rpallares1-Visitor
        1-Visitor
        February 8, 2017

        Hi,

        A better solution for primary keys is to use the GUID type.

        It's not incremential (that prevent bad joins and improve security) and you have a function to get a new GUID:

        var uuid =  generateGUID();

        Regards

          jkaczynski1-Visitor
          1-Visitor
          February 8, 2017

          Hi Rafael PALLARES,

          The GUID is only theoretically​ unique. The better solution is suggested by Tori.

          Hi PREETI GUPTA​,

          If I have more than one DataTable that should have uniquely generated ID's, I'm usually creating another DataTable with fields:

          • DataTable name - here I store the name of DataTable I'm generating ID for,
          • ID - the incremented value of last ID.

          And one service that gets the DataTableName parameter, returns appropriate ID and increments it the same time.

          Regards,

          J.

          rpallares1-Visitor
          1-Visitor
          February 9, 2017

          Hi,

          In effect, the GUID object is only theorically unique (Universally unique identifier - Wikipedia)

          BUT, that probability is :

          Only after generating 1 billion UUIDs every second for the next 100 years, the probability of creating just one duplicate would be about 50%. Or, to put it another way, the probability of one duplicate would be about 50% if every person on earth owned 600 million UUIDs.

          You have much more chances to reach the INTEGER or LONG type limit and have a collision.

          I highlight the fact that all the ThinWorx system use GUID massively for its objects.

          And how do you prevent concurrency accesses to your parameter you increment and use it as primary key?

          I persist and I suggest to use a GUID object. That's made for it.

          Regards.

            Terms & ConditionsAccessibility statement