About DataStores – PB Docs 126

About DataStores

A DataStore is a nonvisual DataWindow control. DataStores
act just like DataWindow controls except that they do not have many
of the visual characteristics associated with DataWindow controls.
Like a DataWindow control, a DataStore has a DataWindow object associated
with it.

note.png Availability

In PowerBuilder, a DataStore is a nonvisual object. The Web
control for ActiveX does not support DataStores.

The Web DataWindow server component uses an instance of a
custom DataStore object to hold the DataWindow definition and data.
See “Using a custom DataStore
object “

When to use a DataStore

DataStores are useful when you need to access data but do
not need the visual presentation of a DataWindow control. DataStores
allow you to:

  • Perform
    background processing against the database without having to hide
    DataWindow controls in a window

    Suppose that the DataWindow object displayed in a DataWindow
    control is suitable for online display but not for printing. In
    this case, you could define a second DataWindow object for printing
    that has the same result set description and assign this object
    to a DataStore. You could then share data between the DataStore
    and the DataWindow control. Whenever the user asked to print the
    data in the window, you could print the contents of the DataStore.

  • Hold data used to show multiple views
    of the same information

    When a window shows multiple views of the same information,
    you can use a DataStore to hold the result set. By sharing data
    between a DataStore and one or more DataWindow controls, you can
    provide different views of the same information without retrieving
    the data more than once.

  • Manipulate table rows without using
    embedded SQL statements

    In places where an application calls for row manipulation
    without the need for display, you can use DataStores to handle the
    database processing instead of embedded SQL statements. DataStores
    typically perform faster at execution time than embedded SQL statements.
    Also, because the SQL is stored with the DataWindow object when
    you use a DataStore, you can easily reuse the SQL.

  • Perform database access on an application

    In a multitier application, the objects in a remote server
    can use DataStores to interact with the database. DataStores let
    you take advantage of the computer resources provided by a server
    machine, removing the need to perform database operations on each

DataStore methods

Most of the methods and events available for DataWindows are
also available for DataStores. However, some of the methods that
handle online interaction with the user are not available. For example,
DataStores support the Retrieve, Update, InsertRow, and DeleteRow
methods, but not GetClickedRow and SetRowFocusIndicator.

Prompting for information

When you are working with DataStores, you cannot use functionality
that causes a dialog box to display to prompt the user for more
information. Here are some examples of ways to overcome this restriction:

SetSort and SetFilter

You can use the SetSort and SetFilter methods to specify
sort and filter criteria for a DataStore object, just as you would
with a DataWindow control. However, when you are working with a
DataWindow control, if you pass a NULL value to either SetSort or
SetFilter, the DataWindow prompts the user to enter information.
When you are working with a DataStore, you must supply a valid format
when you call the method. Moreover, you must supply a valid format
when you share data between a DataStore and a DataWindow control;
you cannot pass the NULL value to the DataWindow control rather
than the DataStore.

Prompt for Criteria

You can define your DataWindow objects so that the user is
prompted for retrieval criteria before the DataWindow retrieves
data. This feature works with DataWindow controls only. It is not
supported with DataStores.


When you use the SaveAs method with a DataWindow object, you can
pass an empty string for the filename argument so that the user
is prompted for a file name to save to. If you are working with
a DataStore, you must supply the filename argument.

Prompt for Printing

For DataWindow controls, you can specify that a print setup
dialog box display at execution time, either by checking the Prompt Before
Printing check box on the DataWindow object’s Print Specifications property
page, or by setting the DataWindow object’s Print.Prompt
property in a script. This is not supported with DataStores.

Retrieval arguments

If you call the Retrieve method for a DataWindow control that
has a DataWindow object that expects an argument, but do not specify
the argument in the method call, the DataWindow prompts the user
for a retrieval argument. This behavior is not supported with DataStores.

DataStores have some visual methods

Many of the methods and events that pertain to the visual
presentation of the data in a DataWindow do not apply to DataStores.
However, because you can print the contents of a DataStore and also
import data into a DataStore, DataStores have some visually oriented
events and methods. For example, DataStores support the SetBorderStyle
and SetSeriesStyle methods so that you can control the presentation
of the data at print time. Similarly, DataStores support the ItemError
event, because data imported from a string or file that does not
pass the validation rules for a column triggers this event.

For a complete list of the methods and events
for the DataStore object and information about each method, see
the DataWindow Reference.

DataStores require no visual overhead

Unlike DataWindow controls, DataStores do not require any
visual overhead in a window. Using a DataStore is therefore more
efficient than hiding a DataWindow control in a window.

Document get from Powerbuilder help
Thank you for watching.
Was this article helpful?
Notify of
Inline Feedbacks
View all comments
Would love your thoughts, please comment.x