openGauss每日一练第2天|学习数据库查询、更新的基本使用

第2天的内容是学习openGauss数据库查询、更新和删除基本使用，其实没有难度。

课程学习

创建数据表

create table customer (
c_customer_sk integer,
c_customer_id char(5),
c_first_name char(6),
c_last_name char(8)
);

向表中插入记录

insert into customer values
(6885, 1, 'Joes', 'Hunter'),    
(4321, 2, 'Lily','Carter'),    
(9527, 3, 'James', 'Cook'),
(9500, 4, 'Lucy', 'Baker');

查看数据

select * from customer;
select * from customer limit 2;
select c_first_name as c_name from customer;

更新数据

update customer set c_customer_sk = c_customer_sk * 2 where c_customer_sk < 5000;

删除数据

delete from customer where c_first_name = 'Lucy';
delete from customer;

删除表

drop table if exists customer;

课后作业

1

create table products (
product_id integer,
product_name char(20),
category char(30)
);

2

insert into products values (1502, 'olympus camera', 'electronics');
insert into products values
(1601, 'lamaze', 'toys'),
(1700, 'wait interface', 'Books'),
(1666, 'harry potter', 'toys');

3

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

4

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

5

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

6

delete from products;
select * from products;

7

drop table if exists products;