💯openGauss每日一练第2天 | 数据库查询、更新和删除基本使用

1.创建一个表products

CREATE TABLE products
(product_id integer,product_name char(30),category char(20));
comment on column products.product_id is '产品编号';
comment on column products.product_name is '产品名';
comment on column products.category is '种类';

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 (product_id,product_name,category) VALUES (1502, 'olympus camera', 'electrncs');
INSERT INTO products 
(product_id,product_name,category) 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;

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;

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;