Using Transaction objects to call stored procedures – PB Docs 115

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Using Transaction objects to call stored procedures

SQLCA is a built-in
global variable of type transaction that is used in all PowerBuilder
applications. In your application, you can define a specialized version
of SQLCA that performs certain
processing or calculations on your data.

If your database supports stored procedures, you might already
have defined remote stored procedures to perform these operations.
You can use the remote procedure call (RPC) technique to define
a customized version of the Transaction object that calls these
database stored procedures in your application.

note.gif Result sets You cannot use the RPC technique to access
result sets returned by stored procedures. If the stored procedure
returns one or more result sets, PowerBuilder ignores the values
and returns the output parameters and return value. If your stored
procedure returns a result set, you can use the embedded SQL DECLARE Procedure statement
to call it.

For information about the DECLARE
Procedure statement, see the chapter on SQL statements in the PowerScript
Reference
.

Overview of the RPC procedure

To call database stored procedures from within your PowerBuilder
application, you can use the remote procedure call technique and
PowerScript dot notation (object.function)
to define a customized version of the Transaction object that calls
the stored procedures.

proc.gif To call database stored procedures in your application:

  1. From the Objects tab in the New dialog
    box, define a standard class user object inherited from the built-in
    Transaction object.

  2. In the Script view in the User Object painter,
    use the RPCFUNC keyword to declare the stored
    procedure as an external function or subroutine for the user object.

  3. Save the user object.

  4. In the Application painter, specify the user object
    you defined as the default global variable type for SQLCA.

  5. Code your PowerBuilder application to use the
    user object.

For instructions on using the User Object
and Application painters and the Script view in PowerBuilder, see
the PowerBuilder Users Guide
.

Understanding the example

u_trans_database user object The following sections give step-by-step instructions for
using a Transaction object to call stored procedures in your application.
The example shows how to define and use a standard class user object
named u_trans_database.

The u_trans_database user
object is a descendant of (inherited from) the built-in
Transaction object SQLCA.
A descendant is an object that inherits functionality
(properties, variables, functions, and event scripts) from an ancestor
object. A descendent object is also called a subclass.

GIVE_RAISE stored procedure The u_trans_database user
object calls an Oracle database stored procedure named GIVE_RAISE that
calculates a five percent raise on the current salary. Here is the
Oracle syntax to create the GIVE_RAISE stored
procedure:

note.gif SQL terminator
character The syntax shown here for creating an Oracle stored procedure
assumes that the SQL statement
terminator character is ` (backquote).

Step 1: define the standard class user object

proc.gif To define the standard class user object:

  1. Start PowerBuilder.

  2. Connect to a database that supports stored procedures.

    The rest of this procedure assumes you are connected to an
    Oracle database that contains remote stored procedures on the database
    server.

    For instructions on connecting to an Oracle
    database in PowerBuilder and using Oracle stored procedures, see Connecting
    to Your Database
    .

  3. Click the New button in the PowerBar, or select
    File>New from the menu bar.

    The New dialog box displays.

  4. On the Object tab, select the Standard Class icon
    and click OK to define a new standard class user object.

    The Select Standard Class Type dialog box displays:

    datrnsct.gif

  5. Select transaction as the
    built-in system type that you want your user object to inherit from,
    and click OK.

    The User Object painter workspace displays so that you can
    assign properties (instance variables) and functions to your user
    object:

Step 2: declare the stored procedure as an external function

FUNCTION or SUBROUTINE declaration

You can declare a non-result-set database stored procedure
as an external function or external subroutine in a PowerBuilder
application. If the stored procedure has a return value, declare
it as a function (using the FUNCTION keyword).
If the stored procedure returns nothing or returns VOID,
declare it as a subroutine (using the SUBROUTINE keyword).

RPCFUNC and ALIAS FOR keywords

You must use the RPCFUNC keyword
in the function or subroutine declaration to indicate that this
is a remote procedure call (RPC) for a database stored procedure
rather than for an external function in a dynamic library. Optionally, you
can use the ALIAS FOR “spname“ expression
to supply the name of the stored procedure as it appears in the
database if this name differs from the one you want to use in your
script.

For complete information about the syntax
for declaring stored procedures as remote procedure calls, see the
chapter on calling functions and events in the PowerScript
Reference
.

proc.gif To declare stored procedures as external functions
for the user object:

  1. In the Script view in the User Object painter,
    select [Declare] from the first list and Local
    External Functions from the second list.

  2. Place your cursor in the Declare Local External
    Functions view. From the pop-up menu or the Edit menu, select Paste
    Special>SQL>Remote
    Stored Procedures.

    PowerBuilder loads the stored procedures from your database
    and displays the Remote Stored Procedures dialog box. It lists the
    names of stored procedures in the current database.

    datrnsp.gif

  3. Select the names of one or more stored procedures
    that you want to declare as functions for the user object, and click
    OK.

    PowerBuilder retrieves the stored procedure declarations from
    the database and pastes each declaration into the view.

    For example, here is the declaration that displays on one
    line when you select sp_addlanguage:

  4. Edit the stored procedure declaration as needed
    for your application.

    Use either of the following syntax formats to declare the
    database remote procedure call (RPC) as an external function or
    external subroutine (for details about the syntax, see the PowerScript
    Reference
    ):

    Here is the edited RPC function declaration for sp_addlanguage:

Step 3: save the user object

proc.gif To save the user object:

  1. In the User Object painter, click the Save
    button, or select
    File>Save from the menu bar.

    The Save User Object dialog box displays.

  2. Specify the name of the user object, comments
    that describe its purpose, and the library in which to save the
    user object.

  3. Click OK to save the user object.

    PowerBuilder saves the user object with the name you specified
    in the selected library.

Step 4: specify the default global variable type for SQLCA

In the Application painter, you must specify the user object
you defined as the default global variable type for SQLCA. When you execute your
application, this tells PowerBuilder to use your standard class
user object instead of the built-in system Transaction object.

note.gif Using your own Transaction object instead of SQLCA This procedure assumes that your application uses the default
Transaction object SQLCA,
but you can also declare and create an instance of your own Transaction
object and then write code that calls the user object as a property of
your Transaction object. For instructions, see the chapter on working
with user objects in the PowerBuilder Users Guide
.

proc.gif To specify the default global variable type for SQLCA:

  1. Click the Open button in the PowerBar,
    or select File>Open from the menu bar.

    The Open dialog box displays.

  2. Select Applications from the Object Type drop-down
    list. Choose the application where you want to use your new user
    object and click OK.

    The Application painter workspace displays.

  3. Select the General tab in the Properties view.
    Click the Additional Properties button.

    The Additional Properties dialog box displays.

  4. Click the Variable Types tab to display the Variable
    Types property page.

  5. In the SQLCA box,
    specify the name of the standard class user object you defined in
    Steps 1 through 3:

    datrnapp.gif

  6. Click OK or Apply.

    When you execute your application, PowerBuilder will use the
    specified standard class user object instead of the built-in system
    object type it inherits from.

Step 5: code your application to use the user object

What you have done so far In the previous steps, you defined the GIVE_RAISE remote
stored procedure as an external function for the u_trans_database standard
class user object. You then specified u_trans_database as
the default global variable type for SQLCA.
These steps give your PowerBuilder application access to the properties
and functions encapsulated in the user object.

What you do now You now need to write code that uses the user object to perform
the necessary processing.

In your application script, you can use PowerScript dot notation
to call the stored procedure functions you defined for the user
object, just as you do when using SQLCA for
all other PowerBuilder objects. The dot notation syntax is:

For example, you can call the GIVE_RAISE stored
procedure with code similar to the following:

proc.gif To code your application to use the user object:

  1. Open the object or control for which you
    want to write a script.

  2. Select the event for which you want to write the
    script.

    For instructions on using the Script view,
    see the PowerBuilder Users Guide
    .

  3. Write code that uses the user object to do the
    necessary processing for your application.

    Here is a simple code example that connects to an Oracle database,
    calls the GIVE_RAISE stored procedure
    to calculate the raise, displays a message box with the new salary,
    and disconnects from the database:

  4. Compile the script to save your changes.

note.gif Using error checking An actual script would include error checking after the CONNECT statement, DISCONNECT statement,
and call to the GIVE_RAISE procedure.
For details, see “Error handling after
a SQL statement”.

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Powerbuilder Documentation 11.5
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August 3, 2023
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