openGauss每日一练第12天 | 学习心得体会

数据类型

这一节课是讲数据库的复合类型，这个比较厉害。

1.练习

CREATE TYPE compfoo AS (f1 int, f2 text);
CREATE TABLE t1_compfoo(a int, b compfoo);
INSERT INTO t1_compfoo values(1,(1,'demo'));
SELECT (b).f1 FROM t1_compfoo;
\d compfoo
CREATE TYPE bugstatus AS ENUM ('create', 'modify', 'closed');

ALTER TYPE compfoo RENAME TO compfoo1;

ALTER TYPE compfoo1 ADD ATTRIBUTE f3 int;
\d compfoo1
select * from t1_compfoo;

ALTER TYPE compfoo1 drop ATTRIBUTE f1;
\d compfoo1
select * from t1_compfoo;

ALTER TYPE bugstatus ADD VALUE IF NOT EXISTS 'regress' BEFORE 'closed';

DROP TYPE compfoo1;
DROP TYPE compfoo1 cascade;
drop type bugstatus;

2.作业

CREATE TYPE jdliu AS(f1 int, f2 int);
ALTER TYPE jdliu RENAME TO jdl;
ALTER TYPE jdl ADD ATTRIBUTE f3 int;
ALTER TYPE jdl DROP ATTRIBUTE f3;

CREATE TYPE ee AS ENUM ('1', '2', '3');
ALTER TYPE ee ADD VALUE IF NOT EXISTS '2.x' before '3';

DROP TYPE ee;