--创建枚举类型。
CREATE TYPE mood AS ENUM ('sad', 'old_value', 'happy');
--创建表
CREATE TABLE person (
name VARCHAR(20),
current_mood mood
);
--插入数据
INSERT INTO person VALUES ('Moe', 'happy');
--查询
SELECT * FROM person WHERE current_mood = 'happy';
--结果
name | current_mood
------+--------------
Moe | happy
(1 row)
--添加列
ALTER TYPE mood ADD VALUE 'new_value';
ALTER TYPE mood ADD VALUE 'new_value' BEFORE 'old_value';
ALTER TYPE mood ADD VALUE 'new_value' AFTER 'old_value';
ALTER TYPE mood ADD VALUE IF NOT EXISTS 'archived' AFTER 'old_value';
--删除列
到目前为止,Postgres没有提供从枚举中删除值的方法.
--删除枚举
DROP TYPE mood;
--查看数据库的所有枚举类型-
SELECT n.nspname AS enum_schema,
t.typname AS enum_name,
e.enumlabel AS enum_value
FROM pg_type t
JOIN pg_enum e ON t.oid = e.enumtypid
JOIN pg_catalog.pg_namespace n ON n.oid = t.typnamespace