openGauss每日一练第 11天：视图管理

视图就像一个活图的窗口，与基本表不同，是一个虚拟的表。数据库中仅存放视图的定义，而不存放视图对应的数据，这些数据仍存放在原来的基本表中。

课程作业：

1.为系统表PG_DATABASE创建视图，重命名视图并修改owner为jim,

CREATE VIEW tdb_view AS SELECT * FROM PG_DATABASE ;
ALTER VIEW tdb_view RENAME TO tdb_view1;
CREATE USER jim PASSWORD'jim@1234';
ALTER  VIEW tdb_view1 OWNER to jim;

2.创建一个用户表student，并在用户表上创建视图，修改视图schema;

CREATE SCHEMA sym;
CREATE TABLE sym.student
(  c_student_sk             integer,   
  c_student_id             char(5),    
  c_first_name              char(6),    
  c_last_name               char(8) 
) ;
INSERT INTO sym.student VALUES    
(6885, 1, 'Joes', 'Hunter'),    
(4321, 2, 'Lily','Carter'),    
(9527, 3, 'James', 'Cook'),
(9500, 4, 'Lucy', 'Baker');
CREATE VIEW sym.student_view_v1 AS SELECT * FROM sym.student;
ALTER VIEW sym.student_view_v1 SET schema public;
SELECT * FROM public.student_view_v1;

3.使用pg_views查看视图信息

SELECT * FROM pg_views WHERE schemaname = 'public';

4.删除视图、表、用户

drop view tdb_view1;
drop view sym.student_view_v1;
drop table sym.student;
drop schema sym;
drop user jim;