Or more generally, using an outer join:

CREATE TABLE MyProducts (ProdID int, ProdGrp char(7))

INSERT INTO MyProducts VALUES

(11, '*')

,(12, '*')

,(13, 'Group A')

,(14, 'Group B')

,(15, 'Group C')

CREATE TABLE MyGroups (ProdGrp char(6), ProdGrpDesc char(7))

INSERT INTO MyGroups VALUES

('A Prod','Group A'),

('B Prod','Group B'),

('C Prod','Group C')

SELECT p.ProdID, p.ProdGrp

FROM MyProducts p

LEFT JOIN MyGroups g

ON p.ProdGrp = '*'

John