Oracle 相关

概念

用户、表空间

docker 安装oracle

参考

Oracle命令

sqlplus  # 连接oracle数据库

表操作

新建

• 唯一约束 unique 不可重复
• 非空约束 not null 不能为空必须制定值
• 主键约束 primary key 通常是给id使用的，同时具备了unique和not null约束
• 外键约束 foreign key

CREATE TABLE hero(
id number primary key,
name varchar2(30),
hp number,
mp number,
damage number,
armor number,
speed number);

修改表

增加字段

ALTER TABLE hero ADD(test number);

删除字段

ALTER TABLE hero DROP COLUMN test;

修改字段

ALTER TABLE hero MODIFY(test VARCHER2(200));

删除

DROP TABLE hero;

记录操作

插入记录

• 插入记录需要COMMIT提交

INSERT INTO hero (id, name, hp, mp, damage, armor, speed) VALUES (hero_seq.nextval, 'link', 233, 904, 232, 23, 233);
COMMIT;

自增id

• 创建序列（SEQUENCE）并指定初始值，在插入记录时传递此序列值
• INCREMENT（步长）

CREATE SEQUENCE hero_seq
INCREMENT by 1
START with 1
MAXVALUE 9999999
-------
INSERT INTO hero (id, name, hp, mp, damage, armor, speed) VALUES (hero_seq.nextval, 'link', 233, 904, 232, 23, 233);
COMMIT;

删除记录

• DELETE删除记录可以回滚数据
• ROLLBACK回滚DELETE的数据
• TRUNCATE删除记录不可回滚

DELETE FROM hero WHERE id = 5;
--COMMIT;   -- 提交后不可回滚
SELECT * FROM hero;
ROLLBACK;

TRUNCATE TABLE hero;  -- 不可回滚

更新记录

UPDATE hero SET id = null WHERE id = 99;

字符串连接

• 字符串连接：||
• hr.employees是Oracle自带表

SELECT e.last_name || ' ' || e.first_name as NAME_  FROM hr.employees e

去重复

• DISTINCT

SELECT DISTINCT e.department_id FROM hr.employees e

回滚

• ROLLBACK

 DELETE FROM hero;
 -- 回滚删除的数据
 ROLLBACK;

设置回滚点

• SAVEPOINT ：设置保存点
• ROLLBACK TO

 UPDATE hero SET name = 'TEST A' WHERE id = 13;
 
 SAVEPOINT A
  
 UPDATE hero SET name = 'TEST B' WHERE id = 13;
 
 SAVEPOINT B
 
 DELETE FROM hero WHERE id = 13
 
 SAVEPOINT C
 -- 回滚到保存点A之前的数据
 ROLLBACK TO A

条件查询

like

• %匹配多个或者没有,_匹配有且只有一个

-- job_id 中以N或者K结尾且必须包含L的字段
SELECT * FROM hr.employees e WHERE (e.job_id like '%N' OR e.job_id like '%K') AND e.job_id like '%L%';

BETWEEN

SELECT * FROM hr.employees e WHERE e.salary BETWEEN 2000 AND 3000

IN

SELECT * FROM hr.employees e WHERE e.Employee_Id IN(116, 130);

分组查询

-- 对员工表按部门分组，且计算部门平均工资
SELECT e, AVG(e.salary) FROM hr.employees e GROUP BY e.department_id

分组条件

• HAVING

-- 对员工表按部门分组，且计算部门平均工资,筛选大于5000的部门
SELECT e.department_id, AVG(e.salary) FROM hr.employees e GROUP BY e.department_id HAVING AVG(e.salary) > 5000

分页查询

• rownum：当前行号

SELECT * FROM(
      SELECT e1.* ,rownum r FROM (
            SELECT * FROM hr.employees e ORDER BY e.salary DESC ) e1
      ) e2 WHERE r > 5 AND r <= 10;

连接查询

-- 查询员工名称（e.first_name）和部门名称（d.department_name）
SELECT e.first_name, d.department_name FROM hr.employees e LEFT JOIN hr.departments d ON e.department_id = d.department_id

存储过程

创建

 CREATE OR REPLACE PROCEDURE test_pro(cnt OUT number)
 AS
 BEGIN
      SELECT count(*) INTO cnt FROM hero;
 END;

调用

CALL test_pro()