第二课 openGauss查询、更新和删除基本使用
学习目标
学习openGauss数据库查询、更新和删除基本使用。
课程学习
连接openGauss
#第一次进入等待15秒
#数据库启动中…
su - omm
gsql -r
学习内容
1.创建数据表
CREATE TABLE customer_t
( c_customer_sk integer,
c_customer_id char(5),
c_first_name char(6),
c_last_name char(8)
) ;
2.向表中插入记录
INSERT INTO customer_t VALUES
(6885, 1, ‘Joes’, ‘Hunter’),
(4321, 2, ‘Lily’,‘Carter’),
(9527, 3, ‘James’, ‘Cook’),
(9500, 4, ‘Lucy’, ‘Baker’);
3.查看数据
–获取表中全部记录
select * from customer_t;
–获取表中两条记录
select * from customer_t limit 2;
–查询表中所有c_first_name的字段，并以别名c_name输出
select c_first_name as c_name from customer_t;
4.更新数据
–更新所有记录
update customer_t set c_customer_id = c_customer_id + 100;
–查看数据
select * from customer_t;
–更新c_customer_sk*2 < 5000的记录
update customer_t set c_customer_sk = c_customer_sk * 2 where c_customer_sk < 5000;
–查看数据
select * from customer_t;
5.删除数据
–删除c_first_name为Lucy的记录
delete from customer_t where c_first_name = ‘Lucy’;
–查看数据
select * from customer_t;
–删除所有数据
delete from customer_t;
–查看数据
select * from customer_t;
6.删除表
drop table customer_t;
课后作业
1.创建一个表products
字段名 数据类型 含义
product_id INTEGER 产品编号
product_name Char(20) 产品名
category Char(30) 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
product_id product_name category
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
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
5.删除category为toys的所有记录，并查看products中数据是否删除成功
6.删除products中所有数据，并查看数据是否删除成功
7.删除表products
create table products(
product_id int,
product_name char(30),
category char(20)
);
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');
select * from products limit 1;
select * from products limit 3;
select * from products;
update products set product_id = product_id-100 where product_id>1600;
select * from products;
delete from products where category = 'toys';
select * from products;
delete from products;
select * from products;
drop table products;
课后作业记录
omm=#
omm=# CREATE TABLE customer_t
omm-# ( c_customer_sk integer,
omm(# c_customer_id char(5),
omm(# c_first_name char(6),
omm(# c_last_name char(8)
omm(# ) ;
CREATE TABLE
omm=#
omm=# INSERT INTO customer_t VALUES
omm-# (6885, 1, 'Joes', 'Hunter'),
omm-# (4321, 2, 'Lily','Carter'),
omm-# (9527, 3, 'James', 'Cook'),
omm-# (9500, 4, 'Lucy', 'Baker');
INSERT 0 4
omm=#
omm=# select * from customer_t;
(4 rows)
omm=# c_customer_sk | c_customer_id | c_first_name | c_last_name
---------------+---------------+--------------+-------------
6885 | 1 | Joes | Hunter
4321 | 2 | Lily | Carter
9527 | 3 | James | Cook
9500 | 4 | Lucy | Baker
omm=# select * from customer_t limit 2;
omm=# c_customer_sk | c_customer_id | c_first_name | c_last_name
---------------+---------------+--------------+-------------
6885 | 1 | Joes | Hunter
4321 | 2 | Lily | Carter
(2 rows)
omm=# select c_first_name as c_name from customer_t;
c_name
--------
Joes
Lily
James
Lucy
(4 rows)
omm=#
omm=# update customer_t set c_customer_id = c_customer_id + 100;
UPDATE 4
omm=#
omm=# select * from customer_t;
c_customer_sk | c_customer_id | c_first_name | c_last_name
---------------+---------------+--------------+-------------
6885 | 101 | Joes | Hunter
4321 | 102 | Lily | Carter
9527 | 103 | James | Cook
9500 | 104 | Lucy | Baker
(4 rows)
omm=#
omm=# update customer_t set c_customer_sk = c_customer_sk * 2 where c_customer_sk < 5000;
UPDATE 1
omm=#
omm=# select * from customer_t;
omm=# c_customer_sk | c_customer_id | c_first_name | c_last_name
---------------+---------------+--------------+-------------
6885 | 101 | Joes | Hunter
9527 | 103 | James | Cook
9500 | 104 | Lucy | Baker
8642 | 102 | Lily | Carter
(4 rows)
omm=# delete from customer_t where c_first_name = 'Lucy';
DELETE 1
omm=# select * from customer_t;
c_customer_sk | c_customer_id | c_first_name | c_last_name
---------------+---------------+--------------+-------------
6885 | 101 | Joes | Hunter
9527 | 103 | James | Cook
8642 | 102 | Lily | Carter
(3 rows)
omm=#
omm=# delete from customer_t;
DELETE 3
omm=#
omm=# select * from customer_t;
c_customer_sk | c_customer_id | c_first_name | c_last_name
---------------+---------------+--------------+-------------
(0 rows)
omm=#
omm=# drop table customer_t;
DROP TABLE
omm=#
omm=#
omm=# create table products(
omm(# product_id int,
omm(# product_name char(30),
omm(# category char(20)
omm(# );
CREATE TABLE
omm=#
omm=# INSERT INTO products(product_id,product_name,category) VALUES (1502,'olympus camera','electrncs');
INSERT 0 1
omm=#
omm=# INSERT INTO products(product_id,product_name,category) VALUES
omm-# (1601, 'lamaze', 'toys'),
omm-# (1700, 'wait interface', 'Books'),
omm-# (1666, 'harry potter', 'toys');
INSERT 0 3
omm=#
omm=# select * from products limit 1;
product_id | product_name | category
------------+--------------------------------+----------------------
1502 | olympus camera | electrncs
(1 row)
omm=#
omm=# select * from products limit 3;
1502 | olympus camera | electrncs
1601 | lamaze | toys
1700 | wait interface | Books
(3 rows)
omm=# product_id | product_name | category
------------+--------------------------------+----------------------
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=#
omm=#
omm=# update products set product_id = product_id-100 where product_id>1600;
UPDATE 3
omm=#
omm=# select * from products;
product_id | product_name | category
------------+--------------------------------+----------------------
1502 | olympus camera | electrncs
1501 | lamaze | toys
1600 | wait interface | Books
1566 | harry potter | toys
(4 rows)
omm=#
omm=# delete from products where category = 'toys';
DELETE 2
omm=# select * from products;
product_id | product_name | category
------------+--------------------------------+----------------------
1502 | olympus camera | electrncs
1600 | wait interface | Books
(2 rows)
omm=#
omm=#
omm=# delete from products;
DELETE 2
omm=# select * from products;
product_id | product_name | category
------------+--------------+----------
(0 rows)
omm=#
omm=# drop table products;
DROP TABLE
omm=#
