sm_bi_compare

Programming Guide

Compares widgets in the current table view with their before-image values
#include <tmusubs.h>
int sm_bi_compare(void);

Returns

DM_TM_ERR_GENERAL if no transaction or table view is available.

Success—one of the following constants:

· BI_UNCHANGED: Occurrence was not changed.

· BI_DELETED: Occurrence was deleted.

· BI_INSERTED: Occurrence was inserted.

· BI_KEY_NULLED: A primary key field in the occurrence was cleared or set to NULL.

· BI_KEY_CHANGED: A primary key field in the occurrence was changed to a non-NULL/non-empty value.

· BI_UPDATED: A non-primary key field in the occurrence was changed.

Description

sm_bi_compare compares an occurrence value with its before-image and returns a code indicating the status of the comparison. Comparison codes are listed above.
The occurrence is the current occurrence number as determined by sm_tm_inquire("TM_OCC"). A positive occurrence number indicates an onscreen occurrence. A negative occurrence number indicates a deleted occurrence; an occurrence is deleted by the logical key DELL or by a call to sm_i_doccur.
In the standard transaction models, the requests TM_INSERT, TM_UPDATE, and TM_DELETE each call sm_bi_compare. This allows the model to choose the appropriate processing for a changed occurrence.
A special case exists when a row's primary key value is set to empty or NULL. The program can do this in one of the following ways:

Write an empty string to the field.

Call sm_tm_command("CLEAR").

Call sm_tm_clear.

In the standard models both the TM_DELETE and TM_INSERT requests test for BI_KEY_CHANGED and both perform processing for this change. Therefore, if a primary key value changes, the standard models delete the occurrence using the before-image value of the primary key and insert a new occurrence using the onscreen value of the primary key. The model may be changed so that TM_UPDATE handles all updates, including primary key changes.
This function operates on the current table view. It is intended to be called from a transaction model or event function.

Example

/* The following example taken from the standard 
		transaction model for JDB shows the processing for the 
		TM_UPDATE request. */

case TM_UPDATE:
		/* Do nothing, except for updates */
	occ_type = sm_bi_compare();
	if (occ_type != BI_UPDATED)
	{
		break;
	}

	if (!reuse_cursor)
	{
		save_cursor_type = 0;
	}
	reuse_cursor = 0;

	sm_tm_push_model_event(TM_UPDATE_EXEC);
	sm_tm_push_model_event(TM_UPDATE_DECLARE);
	sm_tm_push_model_event(TM_GET_SAVE_CURSOR);
	break;