https://wiki.postgresql.org/wiki/Enum
建立enum:
pgsql=# CREATE TYPE mood AS ENUM ('sad', 'ok', 'happy'); CREATE TYPE pgsql=#
建表：
pgsql=# CREATE TABLE person ( pgsql(# name text, pgsql(# current_mood mood pgsql(# ); CREATE TABLE pgsql=#
数据输入：
pgsql=# INSERT INTO person VALUES ('Larry', 'sad'); INSERT 0 1 pgsql=# INSERT INTO person VALUES ('Curly', 'ok'); INSERT 0 1 pgsql=# S
查询:
pgsql=# SELECT * FROM person WHERE current_mood > 'sad'; name | current_mood -------+-------------- Curly | ok (1 row) pgsql=#
