About Transaction objects
In a PowerBuilder database connection, a Transaction
object is a special nonvisual object that functions
as the communications area between a PowerBuilder application and
the database. The Transaction object specifies the parameters that
PowerBuilder uses to connect to a database. You must establish the
Transaction object before you can access the database from your
application, as shown in Figure 12-1:
Figure 12-1: Transaction object to access
database
Communicating with the database
In order for a PowerBuilder application to display and manipulate
data, the application must communicate with the database in which
the data resides.
To communicate with the database from your PowerBuilder
application:
-
Assign the appropriate values to the Transaction
object. -
Connect to the database.
-
Assign the Transaction object to the DataWindow
control. -
Perform the database processing.
-
Disconnect from the database.
For information about setting the Transaction
object for a DataWindow control and using the DataWindow to retrieve
and update data, see the DataWindow Programmers Guide.
Default Transaction object
When you start executing an application, PowerBuilder creates
a global default Transaction object named SQLCA (SQL Communications Area). You can
use this default Transaction object in your application or define
additional Transaction objects if your application has multiple
database connections.
Transaction object properties
Each Transaction object has 15 properties, of which:
-
Ten are used to connect to
the database. -
Five are used to receive status information from
the database about the success or failure of each database operation.
(These error-checking properties all begin with SQL.)