内容
数据库查询、更新和删除基本使用，和第一天的内容比较相似，主要增加数据库的更新操作。
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.创建一个表products
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.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 if exists products;
