Record/Row Locking

..\sdk\sql.php\tutorials\PHP_Tutorial3.php

Now we will explore row/record locks using the <FC_PROD_PHP> Interface.

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.

Like 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 c-treeACE Database Engine.
Define() - Defines and creates a "customer master" (custmast) table/file.
Manage() - Adds a few rows/records; Reads the rows/records back from the database; displays the column/field content. Then demonstrates an update operation under locking control, and a scenario that shows a locking conflict.
Done() - Disconnects from c-treeACE Database Engine.

Note our simple PHP script:

<?php

   print("<html>\n");

   print("<head>\n");

   print("\t<title>PHP Tutorial 3</title>\n");

   print("</head>\n");

   print("<body>\n");

//

   // Implementation of the concept of "init, define, manage and you're done..."

//

   $session = Initialize();

   Defines($session);

   Manage($session);

   Done($session);

We suggest opening the source code with your own editor.

Continue now to review these four steps.

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