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ODBC Driver Guide

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Record/Row Locking

sdk\sql.odbc\tutorials\ODBCTutorial3.c

Now we will explore row/record locks using the c-treeACE SQL ODBC 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 mainline:

/*

* main()

*

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

* and you're done..."

*/

int main(int argc, char* argv[])

{

Initialize();

Define();

Manage();

Done();

printf("\nPress <ENTER> key to exit . . .\n");

getchar();

return(0);

}

We suggest opening the source code with your own editor.

Continue now to review these four steps.

In This Section

Init

Define

Manage

Done

Additional Resources

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