Release 10.1A: OpenEdge Development:
ProDataSets

Using the SAVE-WHERE-STRING attribute

As outlined in the previous section, the first step in saving a change is to locate the database buffer the temp-table row was derived from. Progress can always determine how to identify that row, based on the KEYS phrase of the Data-Source or the primary key of the database table, but it is not always trivial for you to determine the same information in your procedures. For this reason, there is a SAVE-WHERE-STRING attribute on the Data-Source to return to you the where-clause you would need to use to retrieve the same record yourself, as shown:

data-source-handle:SAVE-WHERE-STRING( [ buffer-index | buffer-name ] ).

As with SAVE-ROW-CHANGES, SAVE-WHERE-STRING defaults to the first (or only) buffer in the Data-Source. The attribute value is set internally by Progress to be the where-clause phrase (including the initial keyword WHERE) needed to find the database buffer identified by the buffer-index or buffer-name within the Data-Source. This can be useful when you need to build up custom code to retrieve database records of changed buffers, if using the SAVE-ROW-CHANGES method is not adequate. If you specify a buffer-index, it is the sequential position of the buffer within the list of multiple buffers for the Data-Source. If you specify the buffer-name, it must be the name of an after-table buffer in the list of buffers attached to the Data-Source. The buffer must be one that has a before-table, either static or dynamic. The attribute value qualifies field names in the buffer’s temp-table with the before-table name, not the after-table name. This is because this string can be used to find database records based on field values in the before-table rows, as your code is cycling through the before-table, processing each change.

If an error occurs during the database update, the ERROR attribute is set to true for the ProDataSet, the temp-table where the error occurred, and the buffer where the error occurred.

Table 6–2 summarizes all these change methods and the handles they can be used on.

Table 6–2: Change methods

Method name	ProDataSet handle	Temp-table buffer handle	ROW version
GET-CHANGES	Yes	Yes	None
SAVE-ROW-CHANGES	No	No	Only
MERGE-CHANGES	Yes	Yes	MERGE-ROW-CHANGES
ACCEPT-CHANGES	Yes	Yes	ACCEPT-ROW-CHANGES
REJECT-CHANGES	Yes	Yes	REJECT-ROW-CHANGES

In summary:

You execute a method on a ProDataSet handle to affect the entire ProDataSet.
You execute a method on a temp-table buffer handle to affect that one temp-table.
You don’t execute any of these methods on a temp-table handle. However, the TRACKING-CHANGES attribute is on the temp-table handle.
There’s no row-level method for GET-CHANGES. You execute this only for an entire temp-table or ProDataSet.
There’s only a row-level method for saving changes.
The row-level method is executed on the temp-table buffer handle. The name tells Progress whether to act on a single row or the entire table.