ORACLE STUDY NOTES 01

【JSU】LJDragon's Oracle course notes In the first semester, junior year

DML数据操纵语言

DML指:update,delete,insert等语句

eg1:select语句

1. select e.* from emp e where empno = 7369;

eg2:insert语句

--插入数据 insert into 表名 [(列1，列2，……)] values (值1，值2，……);

--省略列列表，默认就是表中的所有列

--列和值必须要个数，顺序，类型相同

1. --增加一个新部门
2. INSERT
   INTO departments (department_id,department_name,manager_id,location_id)
3. VALUES (120,'NEC',206,1700);
4.  
5. INSERT
   INTO departments
6. VALUES (120,'NEC',206,1700);
7.  
8. INSERT
   INTO departments (department_id,department_name)
9. VALUES (120,'NEC');
10.  
11. INSERT
    INTO departments
12. VALUES (120,'NEC',NULL,NULL);

--插入多行 insert into 表名 [(列1，列2，……)] 子查询;

1. INSERT
   INTO new_dept
2. SELECT * FROM dept;

eg3:update语句

--更新数据 update 表名 set 列1=值,列2=值，……[where 子句]

1. update emp
2. set sal = sal+500,
3. hiredate = (hiredate + 30)
4. where empno = 7902

--修改100员工的姓名为张三

1. UPDATE new_emp
2. SET first_name = '三',
3.        last_name = '张'
4. WHERE employee_id = 100;

--修改60号部门员工的工资上浮50元

1. UPDATE new_emp
2. SET salary = salary + 50
3. WHERE department_id = 60;

--修改103号员工的工资和100号员工相同

1. UPDATE new_emp
2. SET salary = (SELECT salary
3.                  FROM new_emp
4.                  WHERE employee_id = 100)
5. WHERE employee_id = 103;

eg4:清空/删除表

truncate table 表名	delete from 表名 where
--快速删除表，清空整个表 --不能带条件 --不记录日志 --删除表空间 --数据不能回滚	--（之前一直都用这个的） --有带条件 --记录日志 --不删除表空间 --数据可以回滚

--清空学生表

1. select * from stu_tmp;
2. truncate
   table stu_tmp;

--删除数据 delete from 表名 [where 子句]

1. --删除103员工
2. DELETE
   FROM new_emp
3. WHERE employee_id = 103;
4.  
5. --删除50号部门员工
6. DELETE
   FROM new_emp
7. WHERE department_id = 50;
8.  
9. --删除部门名称为IT的部门的员工
10. DELETE
    FROM new_emp
11. WHERE department_id = (SELECT department_id
12.                         FROM departments
13.                         WHERE department_name = 'IT');

eg5:合并表merge

merge into 副表表名 别名

using 主表表名 别名 on (主表.主键=副表.主键)

when matched then

更新语句

when not matched then

插入语句

1. --创建两张员工表并合并
2. CREATE
   TABLE emp1
3. AS
4. SELECT employee_id,last_name,salary
5. FROM employees;
6.  
7. CREATE
   TABLE emp2
8. AS
9. SELECT employee_id,last_name,salary
10. FROM employees;
11.  
12. --合并数据
13. MERGE INTO emp2 e2
14. USING emp1 e1 ON (e1.emp=e2.empno)
15. WHEN MATCHED THEN--匹配上，则更新
16.      UPDATE
    SET e2.ename=e1.ename,e2.sal=e1.sal
17. WHEN
    NOT MATCHED THEN--没有匹配上，插入数据
18.      INSERT
    VALUES (e1.empno,e1.ename,e1.sal)

dcl:grant,revoke

dql:select

ddl:create,drop,alter

tcl:commit,rollback

分析函数

--over函数连续求和

1. select t1.empno,t1.sal,t1.deptno,
2. (select
   sum(t.sal) from emp t where t.deptno = t1.deptno)
3. as 工资总和
4. from emp t1;
5. --------------------------------
6. select t1.*,
7. (select
   sum(t.sal) from emp t where t.deptno = t1.deptno)
8. as 工资总和
9. from emp t1;

1. SELECT empno,
2.        sal,
3.        deptno,
4.        sum(sal) over() AS 总个表总和 , --总个表总和
5.        sum(sal) over(order
   by empno) AS 累计显示 , --累计显示
6.        sum(sal) over(partition by deptno) 工资总和1,
7.        sum(sal) over(partition by deptno order
   by empno) 部门工资总和2
8. FROM emp;

1. SELECT empno,
2.        sal,
3.        deptno,
4.        avg(sal) over() ,
5.        avg(sal) over(partition by deptno)
6.        from emp;

1. SELECT empno,
2.        sal,
3.        deptno,
4.        sum(sal) over(ORDER BY deptno) over1,
5.        SUM(sal) over() over2
6. FROM emp;