0.进入环境

su - omm
gsql -r

1.创建一个表products

CREATE TABLE products
( product_id integer,
product_name char(30),
category char(20)
) ;

2.向表中插入数据，采用一次插入一条和多条记录的方式

一次插入一条

INSERT INTO products VALUES (1502,'olympus camera','electrncs');
-- 回显:
INSERT 0 1

一次加入多条记录

INSERT INTO products VALUES
(1601,'lamaze','toys'),
(1700,'wait interface','Books'),
(1666,'harry potter','toys');
-- 回显:
INSERT 0 3

3.获取表中一条记录、三条记录和所有记录

一条记录

select * from products limit 1;
-- 回显:
product_id |          product_name          |       category
------------+--------------------------------+----------------------
 1502 | olympus camera                 | electrncs
(1 row)

三条记录

select * from products limit 3;
-- 回显:
 product_id |          product_name          |       category
------------+--------------------------------+----------------------
       1502 | olympus camera                 | electrncs
       1601 | lamaze                         | toys
       1700 | wait interface                 | Books
(3 rows)

所有记录

select * from products;
-- 回显:
 product_id |          product_name          |       category
------------+--------------------------------+----------------------
       1502 | olympus camera                 | electrncs
       1601 | lamaze                         | toys
       1700 | wait interface                 | Books
       1666 | harry potter                   | toys
(4 rows)

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;
-- 回显:
UPDATE 3

select * from products;
-- 回显:
 product_id |          product_name          |       category
------------+--------------------------------+----------------------
       1502 | olympus camera                 | electrncs
        601 | lamaze                         | toys
        700 | wait interface                 | Books
        666 | harry potter                   | toys
(4 rows)

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';
-- 回显:
DELETE 2

select * from products;
-- 回显:
 product_id |          product_name          |       category
------------+--------------------------------+----------------------
       1502 | olympus camera                 | electrncs
        700 | wait interface                 | Books
(2 rows)

6.删除products中所有数据，并查看数据是否删除成功

delete from products;
-- 回显:
DELETE 2

select * from products limit 1;
-- 回显:
 product_id | product_name | category
------------+--------------+----------
(0 rows)

7.删除表products

drop table products;

8. 退出

\q