前言：
最近参加了由opengauss、墨天轮、鲲鹏社区一起推出的活动《每日一练 opengauss 3.0.0 数据库在线实训课程》，共21天，墨天轮提供实操环境，特此记录学习笔记。
活动详情：https://www.modb.pro/db/551619
主题
学习查看表的相关信息
学习笔记
1.测试环境准备
–首先创建一张测试表。
drop table if exists test;
create table test(
id bigint,
name varchar(50) not null,
age int default 20,
primary key(id)
);
2.在gsql中查看表的定义、模式和所有者
\d+ test;
\dt+ test;
3.查看某个模式下有哪些表
SELECT table_name FROM information_schema.tables WHERE table_schema='public';
4.查看一个表下有哪些约束
select conname, connamespace, contype, conkey
from pg_constraint
where conrelid in ( select oid
from pg_class
where relname='test');
\d test
查看一个表属于数据库的哪个模式
\x
SELECT * FROM information_schema.tables WHERE table_name='test';
课后作业
1.创建表和约束
|
omm=# drop database if exists musicdb;
NOTICE: database “musicdb” does not exist, skipping
DROP DATABASE
omm=# create tablespace khzy_tbs relative location ‘tablespace/khzy_tbs1’;
CREATE TABLESPACE
omm=# create database khzy with tablespace = khzy_tbs;
CREATE DATABASE
omm=# drop table if exists khzy1;
NOTICE: table “khzy1” does not exist, skipping
DROP TABLE
omm=# create table khzy1(id bigint,name varchar(50) not null,age int default 46,primary key(id));
NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index “khzy1_pkey” for table “khzy1”
CREATE TABLE
omm=#
|
2.使用\d tableNmae命令查看表的定义、模式和所有者
|
omm=# \d+ khzy1;
Table “public.khzy1”
Column | Type | Modifiers | Storage | Stats target | Description
--------±----------------------±-----------±---------±-------------±------------
id | bigint | not null | plain | |
name | character varying(50) | not null | extended | |
age | integer | default 46 | plain | |
Indexes:
“khzy1_pkey” PRIMARY KEY, btree (id) TABLESPACE pg_default
Has OIDs: no
Options: orientation=row, compression=no
omm=# \dt+ khzy1;
List of relations
Schema | Name | Type | Owner | Size | Storage | Description
--------±------±------±------±--------±---------------------------------±------------
public | khzy1 | table | omm | 0 bytes | {orientation=row,compression=no} |
(1 row)
omm=#
|
3.查看某个模式下有哪些表
|
omm=# SELECT table_name FROM information_schema.tables WHERE table_schema=‘public’;
table_name
–~----------
khzy1
(1 row)
omm=#
|
4.查看一个表下有哪些约束
|
omm=# select conname, connamespace, contype, conkey from pg_constraint where conrelid in ( select oid from pg_class where relname=‘khzy1’);
conname | connamespace | contype | conkey
------------±-------------±--------±-------
khzy1_pkey | 2200 | p | {1}
(1 row)
omm=# \d khzy1
Table “public.khzy1”
Column | Type | Modifiers
--------±----------------------±-----------
id | bigint | not null
name | character varying(50) | not null
age | integer | default 46
Indexes:
“khzy1_pkey” PRIMARY KEY, btree (id) TABLESPACE pg_default
omm=#
|
5.查看一个表属于数据库的哪个模式
|
omm=# \x
Expanded display is on.
omm=# SELECT * FROM information_schema.tables WHERE table_name=‘khzy1’;
-[ RECORD 1 ]----------------±----------
table_catalog | omm
table_schema | public
table_name | khzy1
table_type | BASE TABLE
self_referencing_column_name |
reference_generation |
user_defined_type_catalog |
user_defined_type_schema |
user_defined_type_name |
is_insertable_into | YES
is_typed | NO
commit_action |
omm=#
|
总结
通过第15天的学习，对表有了进一步的了解，知道了表的约束，模式等。
