第一课 openGauss创建表、插入记录、查询记录和删除表基本使用
学习目标
学习openGauss数据库创建表、插入记录、查询记录和删除表基本使用
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
root@modb:~#
root@modb:~# su - omm
omm@modb:~$ gsql -r
gsql ((openGauss 2.0.0 build 78689da9) compiled at 2021-03-31 21:03:52 commit 0 last mr )
Non-SSL connection (SSL connection is recommended when requiring high-security)
Type "help" for help.
omm=#
学习内容如下
1.创建数据库
CREATE TABLE customer_t
( c_customer_sk integer,
c_customer_id char(5),
c_first_name char(6),
c_last_name char(8)
) ;
2.向表中插入一条记录
–列出表中各列字段
INSERT INTO customer_t (c_customer_sk, c_customer_id, c_first_name,c_last_name) VALUES (3769, 5, ‘Grace’,‘White’);
–如果已经知道表中字段的顺序，也可不列出表中的字段，和上条语法等效
INSERT INTO customer_t VALUES (3769, 5, ‘Grace’,‘White’);
3.向表中插入多条记录
INSERT INTO customer_t (c_customer_sk, c_customer_id, c_first_name,c_last_name) VALUES
(6885, 1, ‘Joes’, ‘Hunter’),
(4321, 2, ‘Lily’,‘Carter’),
(9527, 3, ‘James’, ‘Cook’),
(9500, 4, ‘Lucy’, ‘Baker’);
4.查看数据
–查看表中记录数
select count(*) from customer_t;
–查看所有记录
select * from customer_t;
–查询表中所有c_first_name记录
select c_first_name from customer_t;
–查询表中所有c_first_name记录，并去掉重复数据
SELECT DISTINCT(c_first_name) from customer_t;
–查询所有记录，且按c_customer_id升序排列
select * from customer_t order by c_customer_id;
–查询c_first_name为Lily的记录
select * from customer_t where c_first_name = ‘Lily’;
5.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(30) 产品名
category Char(20) 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.查询表中所有记录及记录数
4.查询表中所有category记录，并将查询结果按升序排序
5.查询表中category为toys的记录
6.删除表products
课后作业脚本如下
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;
select count(*) from products;
select category from products order by category;
select * from products where category='toys';
drop table products;
课后练习记录
root@modb:~#
root@modb:~# su - oom
su: user oom does not exist
root@modb:~#
root@modb:~# su - omm
omm@modb:~$ gsql -r
failed to connect Unknown:5432.
omm@modb:~$ #第一次进入等待15秒
omm@modb:~$ #数据库启动中...
omm@modb:~$ su - omm
Password:
su: Authentication failure
omm@modb:~$
omm@modb:~$ exit
logout
root@modb:~#
root@modb:~#
root@modb:~#
root@modb:~# su - omm
omm@modb:~$ gsql -r
gsql ((openGauss 2.0.0 build 78689da9) compiled at 2021-03-31 21:03:52 commit 0 last mr )
Non-SSL connection (SSL connection is recommended when requiring high-security)
Type "help" for help.
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=# INSERT INTO customer_t (c_customer_sk, c_customer_id, c_first_name,c_last_name) VALUES (3769, 5, 'Grace','White');
INSERT 0 1
omm=#
omm=# INSERT INTO customer_t (c_customer_sk, c_customer_id, c_first_name,c_last_name) 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 count(*) from customer_t;
count
-------
5
(1 row)
omm=# select * from customer_t;
c_customer_sk | c_customer_id | c_first_name | c_last_name
---------------+---------------+--------------+-------------
3769 | 5 | Grace | White
6885 | 1 | Joes | Hunter
4321 | 2 | Lily | Carter
9527 | 3 | James | Cook
9500 | 4 | Lucy | Baker
(5 rows)
omm=# select c_first_name from customer_t;
c_first_name
--------------
Grace
Joes
Lily
James
Lucy
(5 rows)
omm=# SELECT DISTINCT(c_first_name) from customer_t;
c_first_name
--------------
James
Grace
Lucy
Joes
Lily
(5 rows)
omm=# select * from customer_t order by c_customer_id;
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
3769 | 5 | Grace | White
(5 rows)
omm=# select * from customer_t where c_first_name = 'Lily';
(1 row)
omm=# c_customer_sk | c_customer_id | c_first_name | c_last_name
---------------+---------------+--------------+-------------
4321 | 2 | Lily | Carter
omm=#
omm=# drop table customer_t;
DROP TABLE
omm=#
omm=#
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;
product_id | product_name | category
------------+--------------------------------+----------------------
1502 | olympus camera | electrncs
1601 | lamaze | toys
1700 | wait interface | Books
1666 | harry potter | toys
(4 rows)
omm=#
omm=# select count(*) from products;
count
-------
4
(1 row)
omm=#
omm=# select * from products order by product_id;
product_id | product_name | category
------------+--------------------------------+----------------------
1502 | olympus camera | electrncs
1601 | lamaze | toys
1666 | harry potter | toys
1700 | wait interface | Books
(4 rows)
omm=#
omm=# select category from products order by category;
category
----------------------
Books
electrncs
toys
toys
(4 rows)
omm=#
omm=# select * from products where category='toys';
product_id | product_name | category
------------+--------------------------------+----------------------
1601 | lamaze | toys
1666 | harry potter | toys
(2 rows)
omm=#
omm=# drop table products;
DROP TABLE
omm=#
omm=#
