openGauss每日一练第 1 天 加油

通过第一天的练习,学会了openGauss数据库的创建表、插入记录、查询记录和删除表基本使用

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

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;
5
–查看所有记录

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
(6 rows)
–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;
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

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
3769 | 5 | Grace | White
(6 rows)
–查询c_first_name为Lily的记录

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

drop table customer_t;
DROP TABLE

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

omm=# create table products(product_id integer,product_name Char(30),catgory char(20));
CREATE TABLE
omm=#
omm=# \dt
List of relations
Schema | Name | Type | Owner | Storage
--------+----------+-------+-------+----------------------------------
public | products | table | omm | {orientation=row,compression=no}
(1 row)

omm=# \dt products
(1 row)

omm=# List of relations
Schema | Name | Type | Owner | Storage
--------+----------+-------+-------+----------------------------------
public | products | table | omm | {orientation=row,compression=no}
omm=#

omm=# \d products
Table "public.products"
Column | Type | Modifiers
--------------+---------------+-----------
product_id | integer |
product_name | character(30) |
catgory | character(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
product_id    product_name    category
1502    olympus camera    electrncs
1601    lamaze    toys
1700    wait interface    Books
1666    harry potter    toys

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

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 | catgory
------------+--------------------------------+----------------------
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 catgory from products order by catgory;
catgory
----------------------
Books
electrncs
toys
toys
(4 rows)

5.查询表中category为toys的记录

omm=# select * from products where catgory='toys';
1601 | lamaze | toys
1666 | harry potter | toys
(2 rows)

6.删除表products

omm=# drop table products;
DROP TABLE

第一天学习结束。