Sybase DC38133-01-0902-01 manual Conflict resolution examples, Resolving date conflicts

group or just for the user contained in the Message Agent connection string.

Using the CURRENT The CURRENT REMOTE USER special constant holds the user ID of the REMOTE USER special remote user sending the message. This can be used in RESOLVE UPDATE

constanttriggers that place reports of conflicts into a table, to identify the user producing a conflict.

Conflict resolution examples

This section describes some ways of using RESOLVE UPDATE triggers to handle conflicts.

Resolving date conflicts

	Suppose a table in a contact management system has a column holding the
	most recent contact with each customer.
	One representative talks with a customer on a Friday, but does not upload his
	changes to the consolidated database until the next Monday. Meanwhile, a
	second representative meets the customer on the Saturday, and updates the
	changes that evening.
	There is no conflict when the Saturday UPDATE is replicated to the
	consolidated database, but when the Monday UPDATE arrives it finds the
	row already changed.
	By default, the Monday UPDATE would proceed, leaving the column with
	the incorrect information that the most recent contact occurred on Friday.
	Update conflicts on this column should be resolved by inserting the most
	recent date in the row.
Implementing the	The following RESOLVE UPDATE trigger chooses the most recent of the
solution	two new values and enters it in the database.
	CREATE TRIGGER contact_date RESOLVE UPDATE
	ON contact
	REFERENCING OLD AS old_name
	NEW AS new_name
	FOR EACH ROW
	BEGIN
	IF new_name.contact_date <
	old_name.contact_date THEN
	SET new_name.contact_date
	= old_name.contact_date
	END IF
	END
	If the value being updated is later than the value that would replace it, the
	new value is reset to leave the entry unchanged.

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