openGauss每日一练 | 2.1 openGauss查询、更新和删除基本使用

课后作业

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'),
(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

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

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

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

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

omm=# update products set product_id = product_id - 1000 where product_id > 1600;
UPDATE 3
omm=# select * from products;
 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

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

omm=# delete products where category = 'toys';
DELETE 2
omm=# select * from products;
 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

omm=# delete products;
DELETE 2
omm=# select * from products;
 product_id | product_name | category 
------------+--------------+----------
(0 rows)

7.删除表products

omm=# drop table products;
DROP TABLE

openGauss SQL学习参考资料