MySQL UPDATE and SELECT in one pass

Question

I have a MySQL table of tasks to perform, each row having parameters for a single task.
There are many worker apps (possibly on different machines), performing tasks in

Answer 1

UPDATE tasks
SET guid = %d, params = @params := params
WHERE guid = 0 LIMIT 1;

It will return 1 or 0, depending on whether the values were effectively changed.

SELECT @params AS params;

This one just selects the variable from the connection.

From: here