how to use composite type

hi,
 I created a composite type as follows, but I couldn't know how to use it.

test=# create type test_type as (id int, name char(20));
CREATE TYPE
test=# create table student( a test_type);
ERROR:  Attribute "a" has composite type test_type

who can tell me? thanks!bigapple
　　　　　　　　
　　　　　　　　　　2002-12-27