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c-treeDB API for VB.Net

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Record/Row Locking


Now we will explore row/record locks using the c-treeDB .NET Visual Basic NAV Framework.

The functionality for this tutorial focuses on inserting/adding rows/records, then updating a single row/record in the customer master table under locking control. The application will pause after a LOCK is placed on a row/record. Another instance of this application should then be launched, which will block, waiting on the lock held by the first instance. Pressing the <Enter> key will enable the first instance to proceed. This will result in removing the lock thereby allowing the second instance to continue execution. Launching two processes provides a visual demonstration of the effects of locking and a basis for experimentation on your own.

As with all other examples in the c-tree tutorial series, this tutorial simplifies the creation and use of a database into four simple steps: Initialize(), Define(), Manage(), and you’re Done() !

Tutorial #3: Locking

Here we demonstrate the enforcement of data integrity by introducing record/row "locking".

  • Initialize() - Connects to the FairCom Database Engine.
  • Define() - Defines and creates a "customer master" (custmast) table/file.
  • Manage() - Adds a few rows/records, manipulates them, and displays the results.
  • Done() - Disconnects from FairCom Database Engine.

Note our simple Main() function:

Imports System

Imports FairCom.CtreeDb

Module Tutorial3HL

Dim MySession As CTSession

Dim MyTable As CTTable

Dim MyRecord As CTRecord


' main()


' The main() function implements the concept of "init, define, manage

' and you're done..."


Sub Main()





Console.WriteLine(ControlChars.NewLine + "Press <ENTER> key to exit . . .")


End Sub

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