openGauss每日一练第１天 |创建表、插入记录、查询记录和删除表基本使用-学习笔记

连接openGauss
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=#
复制
1.创建表
omm=# CREATE TABLE customer_t
( c_customer_sk integer,
c_customer_id char(5),
c_first_name char(6),
c_last_name char(8)
) ;
CREATE TABLE
omm=# \d
List of relations
Schema | Name | Type | Owner | Storage
--------+------------+-------+-------+----------------------------------
public | customer_t | table | omm | {orientation=row,compression=no}
(1 row)

omm=#
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
omm=# select count(*) from customer_t;
count
-------
5
(1 row)

--查看所有记录
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)

--查询表中所有 c_first_name 记录内容
omm=# select c_first_name from customer_t;
c_first_name
--------------
Grace
Joes
Lily
James
Lucy
(5 rows)

--查询表中所有 c_first_name 记录，并去掉重复数据
omm=# SELECT DISTINCT(c_first_name) from customer_t;
c_first_name
--------------
James
Grace
Lucy
Joes
Lily
(5 rows)

--查询所有记录，且按c_customer_id升序排列
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)

--查询c_first_name为Lily的记录
omm=# select * from customer_t where c_first_name = 'Lily';
c_customer_sk | c_customer_id | c_first_name | c_last_name
---------------+---------------+--------------+-------------
4321 | 2 | Lily | Carter
(1 row)
5.删除表
omm=# drop table customer_t;
DROP TABLE
omm=# \d
No relations found.
omm=#

课后作业
1.创建一个表 products

omm=# CREATE TABLE products
omm-# ( product_id integer,
omm(# product_name char(30),
omm(# category char(20)
omm(# ) ;
CREATE TABLE
omm=# COMMENT ON COLUMN products.product_id IS '产品编号';
COMMENT
omm=# COMMENT ON COLUMN products.product_name IS '产品名';
COMMENT
omm=# COMMENT ON COLUMN products.category IS '种类';
COMMENT
omm=# \d+ products
Table "public.products"
Column | Type | Modifiers | Storage | Stats target | Description
--------------+---------------+-----------+----------+--------------+--------------
product_id | integer | | plain | | 产品编号
product_name | character(30) | | extended | | 产品名
category | character(20) | | extended | | 种类
Has OIDs: no
Options: orientation=row, compression=no

2.向表中插入数据，采用一次插入一条和多条记录的方式


omm=# INSERT INTO products VALUES (1502, 'olympus camera','electrncs');
INSERT 0 1
omm=# INSERT INTO products VALUES
omm-# (1601, 'lamaze','toys'),
omm-# (1700, 'wait interface','Books'),
omm-# (1666, 'harry potter','toys');

3.查询表中所有记录及记录数
omm=# select count(*) from products;
count
-------
4
(1 row)

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)
4.查询表中所有 category 记录，并将查询结果按升序排序
omm=# SELECT category from products order by category;

toys
(4 rows)

omm=# category
----------------------
Books
electrncs
toys
5.查询表中 category 为 toys 的记录
omm=# SELECT * from products where category = 'toys';
product_id | product_name | category
------------+--------------------------------+----------------------
1601 | lamaze | toys
1666 | harry potter | toys
(2 rows)
6.删除表 products
omm=# drop table products;
DROP TABLE