select a.c_name,b.c_name from test a inner join test2 b on
(a.c_gongyi like convert(varchar(100),b.c_id)+',%'
or
a.c_gongyi like '%,'+convert(varchar(100),b.c_id)+',%'
or
a.c_gongyi like '%,'+convert(varchar(100),b.c_id)
or
a.c_gongyi =CONVERT(varchar(100),b.c_id)
)