Internal transaction management
What it does
When the DataWindow control uses internal transaction
management, it handles connecting, disconnecting, commits, and
rollbacks. It automatically performs connects and disconnects as
needed; any errors that occur cause an automatic rollback.
Whenever the DataWindow needs to access the database (such as
when a Retrieve or Update method is executed), the DataWindow issues
an internal CONNECT statement, does the appropriate data access, then
issues an internal DISCONNECT.
Whether to use it
When not to use it
Do not use internal transaction management when:
-
Your application requires the best possible
performanceInternal transaction management is slow and uses
considerable system resources because it must connect and
disconnect for every database access. -
You want control over when a transaction is committed or
rolled backBecause internal transaction management must disconnect
after a database access, any changes are always committed
immediately.
When to use it
If the number of available connections at your site is limited,
you might want to use internal transaction management because
connections are not held open.
Internal transaction management is appropriate in simple
situations when you are doing pure retrievals (such as in reporting)
and do not need to hold database locks — when application control
over committing or rolling back transactions is not an issue.
How it works
PowerBuilder
To use internal transaction management, you specify connection
values for a transaction object, which could be the automatically
instantiated SQLCA. Then you call the SetTrans method, which copies
the values from a specified transaction object to the DataWindow
control’s internal transaction object.
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SQLCA.DBMS = ProfileString("myapp.ini", & "database", "DBMS", " ") ... // Set more connection parameters dw_employee.SetTrans(SQLCA) dw_employee.Retrieve( ) |
Connecting to the database
When you use SetTrans, you do not need to explicitly code a
CONNECT or DISCONNECT statement in a script. CONNECT and DISCONNECT
statements are automatically issued when needed.
For more information about PowerBuilder transaction objects, see
the section called “Using Transaction Objects” in Application Techniques.