-- 1. 创建序列
CREATE SEQUENCE test_i_id_seq;

-- 2. 修改字段默认值
ALTER TABLE test 
ALTER COLUMN i_id SET DEFAULT nextval('test_i_id_seq');

-- 3. 同步序列值
SELECT setval('test_i_id_seq', (SELECT MAX(i_id) FROM test));

-- 4. 设置归属关系
ALTER SEQUENCE test_i_id_seq OWNED BY test.i_id;