PowerBuilder follows this order of precedence to supply the data in your DataWindow object:
If you have saved data in the DataWindow object, PowerBuilder uses the saved rows from the DataWindow object and does not retrieve data from the database.
PowerBuilder uses the data in the cache, if there is any.
If there is no data in the cache yet, PowerBuilder retrieves data from the database automatically, with one exception. If the Retrieve on Preview option is off, you have to request retrieval explicitly, as described next.
If you do not want PowerBuilder to retrieve data from the database automatically when the Preview view opens, you can clear the Retrieve on Preview option. The Preview view shows the DataWindow object without retrieving data.
To be able to preview without retrieving data
automatically:
Select Design>Options from the menu bar.
The DataWindow Options dialog box displays.
Clear the Retrieve on Preview check box on the General page.
When this check box is cleared, your request to preview the DataWindow object does not result in automatic data retrieval from the database.
Retrieve on Preview check box is available in the DataWindow wizards
During the initial creation of a DataWindow object, you can set the
Retrieve on Preview option.
When PowerBuilder first retrieves data, it stores the data internally. When it refreshes the Preview view, PowerBuilder displays the stored data instead of retrieving rows from the database again. This can save you a lot of time, since data retrieval can be time consuming.
Because PowerBuilder accesses the cache and does not automatically retrieve data every time you preview, you might not have what you want when you preview. The data you see in preview and the data in the database can be out of sync.
For example, if you are working with live data that changes frequently or with statistics based on changing data and you spend time designing the DataWindow object, the data you are looking at may no longer match the database. In this case, retrieve again just before printing.
You can explicitly request retrieval at any time.
To retrieve rows from the database:
Do one of the following:
Click the Retrieve button in the PainterBar.
Select Rows>Retrieve from the menu bar.
Select Retrieve from the Preview view’s pop-up menu.
Supplying argument values or criteria
If the DataWindow object has retrieval arguments or is set up to
prompt for criteria, you are prompted to supply values for the arguments
or to specify criteria.
PowerBuilder retrieves the rows. As PowerBuilder retrieves, the Retrieve button changes to a Cancel button. You can click the Cancel button to stop the retrieval at any time.
The Data view displays data that can be used to populate a DataWindow object. When the ShareData pop-up menu item in the Data view is checked, changes you make in the Data view are reflected in the Preview view and vice versa.
These other options can affect retrieval:
Retrieve Rows As Needed Lets you specify that only the rows needed to display the current portion of the DataWindow object should be retrieved. When you scroll downward, additional rows are retrieved. This can speed up reporting in certain situations.
Retrieve Rows to Disk Lets you specify that PowerBuilder should save retrieved data on your hard disk in a temporary file rather than keep the data in memory. When you preview the DataWindow object, PowerBuilder swaps rows of data from the temporary file into memory as needed.
For information, see “Saving retrieved rows to disk”.
