学习目标

学习openGauss导入数据

课程学习

连接数据库
#第一次进入等待15秒
#数据库启动中...

su - omm
gsql -r

1.通过INSERT语句直接写入数据

CREATE TABLE reason_t1
(
r_reason_sk integer,
r_reason_id character(16),
r_reason_desc character(100)
);
insert into reason_t1 values(1, 'AAAAAAAABAAAAAAA', 'reason1');

–没有数值的字段将被填充为字段的缺省值

insert into reason_t1 values(1, 'AAAAAAAABAAAAAAA');

–明确字段为缺省值

insert into reason_t1 values(1, 'AAAAAAAABAAAAAAA', DEFAULT);

–明确整行为缺省值

insert into reason_t1 DEFAULT VALUES;
select * from reason_t1;

–指定表插入数据到当前表

CREATE TABLE reason_t2
(
r_reason_sk integer,
r_reason_id character(16),
r_reason_desc character(100)
);

–将查询结果作为插入的数据

INSERT INTO reason_t2 SELECT * FROM reason_t1;
select * from reason_t2;

2.使用合并方式更新和插入数据

–创建源表products，并插入数据

CREATE TABLE products
( product_id INTEGER,
product_name VARCHAR2(60),
category VARCHAR2(60)
);
INSERT INTO products VALUES
(1502, 'olympus camera', 'electrncs'),
(1601, 'lamaze', 'toys'),
(1666, 'harry potter', 'toys'),
(1700, 'wait interface', 'books');

–创建目标表newproducts，并插入数据

CREATE TABLE newproducts
( product_id INTEGER,
product_name VARCHAR2(60),
category VARCHAR2(60)
);
INSERT INTO newproducts VALUES
(1501, 'vivitar 35mm', 'electrncs'),
(1502, 'olympus ', 'electrncs'),
(1600, 'play gym', 'toys'),
(1601, 'lamaze', 'toys'),
(1666, 'harry potter', 'dvd');

–使用MERGE INTO 语句将源表products的数据合并至目标表newproducts

MERGE INTO newproducts np
USING products p
ON (np.product_id = p.product_id )
WHEN MATCHED THEN
UPDATE SET np.product_name = p.product_name, np.category = p.category
WHEN NOT MATCHED THEN
INSERT VALUES (p.product_id, p.product_name, p.category) ;

–查询合并后的目标表newproducts。

SELECT * FROM newproducts

3.使用COPY实现表和文件间的拷贝

–将表数据输出到stdout

copy reason_t1 to stdout;

–将表数据拷贝到文件

copy reason_t1 to '/home/omm/reason.dat';
CREATE TABLE reason_t3 (LIKE reason_t1);

–将数据从文件拷贝到表

copy reason_t3 from '/home/omm/reason.dat';
select * from reason_t3;

课程作业

1.创建表1并在表中插入数据，分别指定字段和整行为缺省值

CREATE TABLE reason_t1
(
id integer,
name character(16),
class character(100)
);
insert into reason_t1 values(1,'AAAAA');
insert into reason_t1 DEFAULT VALUES;
select * from reason_t1;

2.创建表2并将表1的数据全部导入表2中

CREATE TABLE reason_t2 as select * from reason_t1;

3.创建表3和表4，并合并两个表的数据到表3

--创建表3

CREATE TABLE reason_t3
(
id integer,
name character(16)
);
insert into reason_t3 values (1,'一年级'),(2,'二年级'),(3,'三年级');

--创建表4

CREATE TABLE reason_t4
(
id integer,
name character(16)
);
insert into reason_t4 values (1,'一年级'),(4,'四年级'),(5,'五年级');

–使用MERGE INTO 语句将源表reason_t3的数据合并至目标表reason_t4

MERGE INTO reason_t4 np
USING reason_t3 p
ON (np.id = p.id )
WHEN MATCHED THEN
UPDATE SET np.name = p.name
WHEN NOT MATCHED THEN
INSERT VALUES (p.id, p.name) ;
select * from reason_t4;
select * from reason_t3;

4.将表3的数据输出到文件，再将文件中的数据导入到表5

–将表数据拷贝到文件

copy reason_t3 to '/home/omm/reason_t3.dat';
CREATE TABLE reason_t5 (LIKE reason_t3);

–将数据从文件拷贝到表

copy reason_t5 from '/home/omm/reason_t3.dat';
select * from reason_t5;