Multiuser database access

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  • cj
    #1

    Multiuser database access

    The program I just finished allows users to pull a set of records from
    sql server and edit them. It is meant to be a one user system but it
    makes me start thinking. Suppose two users use the program at the same
    time. Both get the same starting set of data. Both users change the
    same records but not the same way and they both save. I assume the last
    one to save is the way the record will end up in sql server. Suppose
    that is not correct. What do we do to ensure the second user gets an
    error that that record has changed since they loaded it? Is there
    record locking etc available in VB? How do programmers deal with this
    these days?
    Tags: None
    • Armin Zingler
      #2
      Re: Multiuser database access

      "cj" <cj@nospam.nosp amschrieb
      The program I just finished allows users to pull a set of records
      from sql server and edit them. It is meant to be a one user system
      but it makes me start thinking. Suppose two users use the program
      at the same time. Both get the same starting set of data. Both
      users change the same records but not the same way and they both
      save. I assume the last one to save is the way the record will end
      up in sql server. Suppose that is not correct. What do we do to
      ensure the second user gets an error that that record has changed
      since they loaded it? Is there record locking etc available in VB?
      How do programmers deal with this these days?

      http://msdn2.microsoft.com/en-us/lib...cz(VS.90).aspx



      Armin

        Comment

        • cj
          #3
          Re: Multiuser database access

          Finally an article in MSDN I understand, although I think I'll have to
          try a few things when I get back to the office next week.

          Now this covered optimistic concurrency. Can we do pessimistic
          concurrency in VB? Do you have a link to that?


          Armin Zingler wrote:
          "cj" <cj@nospam.nosp amschrieb
          >The program I just finished allows users to pull a set of records
          >from sql server and edit them. It is meant to be a one user system
          >but it makes me start thinking. Suppose two users use the program
          >at the same time. Both get the same starting set of data. Both
          >users change the same records but not the same way and they both
          >save. I assume the last one to save is the way the record will end
          >up in sql server. Suppose that is not correct. What do we do to
          >ensure the second user gets an error that that record has changed
          >since they loaded it? Is there record locking etc available in VB?
          >How do programmers deal with this these days?
          >
          >
          http://msdn2.microsoft.com/en-us/lib...cz(VS.90).aspx
          >
          >
          >
          Armin

            Comment

            • Armin Zingler
              #4
              Re: Multiuser database access

              "cj" <cj@nospam.nosp amschrieb
              Finally an article in MSDN I understand, although I think I'll have
              to try a few things when I get back to the office next week.
              >
              Now this covered optimistic concurrency. Can we do pessimistic
              concurrency in VB? Do you have a link to that?
              >
              >
              Armin Zingler wrote:
              "cj" <cj@nospam.nosp amschrieb
              The program I just finished allows users to pull a set of
              records from sql server and edit them. It is meant to be a one
              user system but it makes me start thinking. Suppose two users
              use the program at the same time. Both get the same starting
              set of data. Both users change the same records but not the
              same way and they both save. I assume the last one to save is
              the way the record will end up in sql server. Suppose that is
              not correct. What do we do to ensure the second user gets an
              error that that record has changed since they loaded it? Is
              there record locking etc available in VB? How do programmers
              deal with this these days?

              http://msdn2.microsoft.com/en-us/lib...cz(VS.90).aspx

              No, can't provide a link. I'd ask in the ADO.Net group:
              microsoft.publi c.dotnet.framew ork.adonet

              A cross-language question, IMO.


              Armin

                Comment

                • WenYuan Wang [MSFT]
                  #5
                  Re: Multiuser database access

                  Hello cj,

                  Pessimistic locking is not natively supported in ADO.NET. However, we can
                  achieve this type of locking through transactions. The following article is
                  a sample about it.
                  .xyz - Wikipedia
                  http://articles.techrepublic.com.com/5100-22-1049842.html

                  [Pessimistic locking solves ADO.NET concurrency problems]

                  Hope this helps. If there is anything unclear, feel free to update here
                  again. We are glad to assist you.

                  Have a great day,

                  Best regards,
                  Wen Yuan
                  Microsoft Online Community Support
                  =============== =============== =============== =====
                  This posting is provided "AS IS" with no warranties, and confers no rights.

                    Comment

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