About controlling updates
When PowerBuilder generates the basic DataWindow object, it defines whether
the data is updatable by default as follows:
- If the DataWindow object contains columns from a single
table and includes that table’s key columns, PowerBuilder defines
all columns as updatable and specifies a nonzero tab order for each
column, allowing users to tab to the columns. - If the DataWindow object contains columns from two or more
tables or from a view, PowerBuilder defines all columns as not being updatable
and sets all tab orders to zero, preventing users from tabbing
to them.
You can accept the default settings or modify the update characteristics
for a DataWindow object.
If using a Stored Procedure or External data source If the data source is Stored Procedure or External, you can
use the GetNextModified method
to write your own update script. For more information,
see the DataWindow Reference.
What you can do
You can:
- Allow updates
in a DataWindow object associated with multiple tables or a view; you can
define one of the tables as being updatable - Prevent updates in a DataWindow object associated with
one table - Prevent updates to specific columns in a DataWindow object that
is associated with an updatable table - Specify which columns uniquely identify a row to
be updated - Specify which columns will be included in the WHERE clause
of the UPDATE or DELETE statement PowerBuilder generates
to update the database - Specify whether PowerBuilder generates an UPDATE statement,
or a DELETE then an INSERT statement,
to update the database when users modify the values in a key
column
Updatability of views Some views are logically updatable; some are not. For the
rules your DBMS follows for updating views, see your DBMS documentation.
To specify update characteristics for a DataWindow object:
-
Select Rows>Update Properties
from the menu bar.The Specify Update Properties dialog box displays.
-
To prevent updates to the data, make sure the
Allow Updates box is not selected.To allow updates, select the Allow Updates box and specify
the other settings as described below. -
Click OK.
Changing tab values
PowerBuilder does not change the tab values associated with
columns after you change the update characteristics of the DataWindow object.
If you have allowed updates to a table in a multitable DataWindow object,
you should change the tab values for the updatable columns so that users can
tab to them.
For more information, see “Defining the tab order
in a DataWindow object”.