Этот синтаксис назначит 5 случайных задач каждому человеку:
DECLARE @p table(id int identity, name varchar(40))
DECLARE @t table(id int, taskname varchar(50))
INSERT @p values('Joe'),('Mark'),('Demi'),('Thomas')
INSERT @t(id)
VALUES(1),(2),(3),(4),(5),(6),(7),(8),(9),(10),(11)
,(12),(13),(14),(15),(16),(17),(18),(19),(20)
UPDATE @t set taskname = 'task' + cast(id as varchar(2))
;WITH CTE as
(
SELECT taskname, ntile(4) over(order by newid()) rnd_id
FROM @t
)
SELECT p.name, cte.taskname
FROM CTE
JOIN @p p
ON p.id = cte.rnd_id