openGauss每日一练第2天|课后练习

数据库连接及环境检查

切换用户至omm用户（gaussdb的所有者）

su - omm

gsql连接数据库,并检查当前会话连接信息:

gsql -r
\conninfo

检查当前用户下的表

omm=# \d
No relations found.
omm=#

课后练习

1.创建一个表products

字段名 数据类型 含义
product_id INTEGER 产品编号
product_name Char(30) 产品名
category Char(20) 种类

--创建一个简单表并加表及字段注释

create table products
(product_id integer,
product_name char(30),
category char(20)
);
comment on table products is '产品'; 
comment on column products.product_id is '产品编号';
comment on column products.product_name is '产品名称';
comment on column products.category is '产品种类';

\d+
\d+ products

2.向表中插入数据，采用一次插入一条和多条记录的方式

INSERT INTO products VALUES (1502,'olympus camera','electrncs');
				 
INSERT INTO products VALUES    
(1601,'lamaze','toys'),    
(1700,'wait interface','Books'),    
(1666,'harry potter','toys'); 

3.获取表中一条记录、三条记录和所有记录

select * from products limit 1;
select * from products limit 3;
select * from products;

4.将满足product_id > 1600的记录的product_id更新为product_id – 1000，并查看products中所有记录是否更新成功

update products set product_id = product_id-1000 where product_id > 1600;
select * from products where product_id > 1600;
select * from products;

5.删除category为toys的所有记录，并查看products中数据是否删除成功

delete from products where category = 'toys';
select * from products where category = 'toys';
select * from products;

6.删除products中所有数据，并查看数据是否删除成功

delete from products;
select * from products;

7.删除表products

drop table products;
\d