学习openGauss定义数据类型,课后作业打卡；

1.创建一个复合类型，重命名复合类型，为复合类型增加属性、删除属性

create type my_type as (fuhe01 int,fuhe02 char(20));
alter type my_type rename to my_type_new;
alter type my_type_new add attribute fuhe03 int;
alter type my_type_new drop attribute fuhe01;
\d my_type_new

2.创建一个枚举类型，新增标签值，重命名标签值

create type type_meiju as enum ('tab1','tab2','tab3');
select * from pg_enum;
alter type type_meiju add value if not exists 'tab4' before 'tab3';
alter type type_meiju rename value 'tab4' to 'tab5';
omm=# select * from pg_enum;
 enumtypid | enumsortorder | enumlabel 
-----------+---------------+-----------
     16393 |             1 | tab1
     16393 |             2 | tab2
     16393 |             3 | tab3
     16393 |           2.5 | tab5
(4 rows)

3.使用新创建的类型创建表

create table t_ddzj (id int,name my_type_new,type type_meiju);
insert into t_ddzj values (1,('china',1),'tab1');
insert into t_ddzj values (2,('beijing',2),'tab3');
insert into t_ddzj values (2,('shanghai',2));
insert into t_ddzj values (3,('guangzhou',3));
select * from t_ddzj;
select id,(name).fuhe02,type from t_ddzj;

4.删除类型

drop type my_type_new cascade;
drop type type_meiju cascade;

omm=# drop type my_type_new cascade;
NOTICE:  drop cascades to table t_ddzj column name
DROP TYPE
omm=# drop type type_meiju cascade;
NOTICE:  drop cascades to table t_ddzj column type
DROP TYPE