postgreSQL让主键自增

1.建表时创建

CREATE TABLE test
(  
  test_id SERIAL primary key ,  
  test_name character varying,  
  contactname character varying,  
  phone character varying,  
  country character varying  
)

2.在已建表的情况下创建

CREATE SEQUENCE test_id_seq  
START WITH 1  
INCREMENT BY 1  
NO MINVALUE  
NO MAXVALUE  
CACHE 1;  
  
alter table test alter column id set default nextval('test_id_seq');