记录——Oracle OVER(PARTITION BY

--创建EMP表，插入初始化数据

create table EMP  
(  
  empno    NUMBER(4) not null,  
  ename    VARCHAR2(10),  
  job      VARCHAR2(9),  
  mgr      NUMBER(4),  
  hiredate DATE,  
  sal      NUMBER(7,2),  
  comm     NUMBER(7,2),  
  deptno   NUMBER(2)  
)  
alter table EMP  
  add constraint PK_EMP primary key (EMPNO);  
  
insert into EMP (empno, ename, job, mgr, hiredate, sal, comm, deptno)   
       values (7369, 'SMITH', 'CLERK', 7902, to_date('17-12-1980', 'dd-mm-yyyy'), 800, null, 20);  
insert into EMP (empno, ename, job, mgr, hiredate, sal, comm, deptno)   
       values (7499, 'ALLEN', 'SALESMAN', 7698, to_date('20-02-1981', 'dd-mm-yyyy'), 1600, 300, 30);  
insert into EMP (empno, ename, job, mgr, hiredate, sal, comm, deptno)   
       values (7521, 'WARD', 'SALESMAN', 7698, to_date('22-02-1981', 'dd-mm-yyyy'), 1250, 500, 30);  
insert into EMP (empno, ename, job, mgr, hiredate, sal, comm, deptno)   
       values (7566, 'JONES', 'MANAGER', 7839, to_date('02-04-1981', 'dd-mm-yyyy'), 2975, null, 20);  
insert into EMP (empno, ename, job, mgr, hiredate, sal, comm, deptno)   
       values (7654, 'MARTIN', 'SALESMAN', 7698, to_date('28-09-1981', 'dd-mm-yyyy'), 1250, 1400, 30);  
insert into EMP (empno, ename, job, mgr, hiredate, sal, comm, deptno)   
       values (7698, 'BLAKE', 'MANAGER', 7839, to_date('01-05-1981', 'dd-mm-yyyy'), 2850, null, 30);  
insert into EMP (empno, ename, job, mgr, hiredate, sal, comm, deptno)   
       values (7782, 'CLARK', 'MANAGER', 7839, to_date('09-06-1981', 'dd-mm-yyyy'), 2450, null, 10);  
insert into EMP (empno, ename, job, mgr, hiredate, sal, comm, deptno)   
       values (7788, 'SCOTT', 'ANALYST', 7566, to_date('19-04-1987', 'dd-mm-yyyy'), 3000, null, 20);  
insert into EMP (empno, ename, job, mgr, hiredate, sal, comm, deptno)   
       values (7839, 'KING', 'PRESIDENT', null, to_date('17-11-1981', 'dd-mm-yyyy'), 5000, null, 10);  
insert into EMP (empno, ename, job, mgr, hiredate, sal, comm, deptno)   
       values (7844, 'TURNER', 'SALESMAN', 7698, to_date('08-09-1981', 'dd-mm-yyyy'), 1500, 0, 30);  
insert into EMP (empno, ename, job, mgr, hiredate, sal, comm, deptno)   
       values (7876, 'ADAMS', 'CLERK', 7788, to_date('23-05-1987', 'dd-mm-yyyy'), 1100, null, 20);  
insert into EMP (empno, ename, job, mgr, hiredate, sal, comm, deptno)   
       values (7900, 'JAMES', 'CLERK', 7698, to_date('03-12-1981', 'dd-mm-yyyy'), 950, null, 30);  
insert into EMP (empno, ename, job, mgr, hiredate, sal, comm, deptno)   
       values (7902, 'FORD', 'ANALYST', 7566, to_date('03-12-1981', 'dd-mm-yyyy'), 3000, null, 20);  
insert into EMP (empno, ename, job, mgr, hiredate, sal, comm, deptno)   
       values (7934, 'MILLER', 'CLERK', 7782, to_date('23-01-1982', 'dd-mm-yyyy'), 1300, null, 10);  

问题1：找到每个组分数最高的人

SELECT *
  FROM EMP E2,
       (SELECT MAX(SAL) SAL, E1.DEPTNO FROM EMP E1 GROUP BY DEPTNO) E11
 WHERE E2.SAL = E11.SAL
   AND E2.DEPTNO = E11.DEPTNO;

借用PARTITION BY

SELECT *
  FROM (SELECT MAX(SAL) OVER(PARTITION BY E1.DEPTNO) MAXSAL, E1.*
          FROM EMP E1) E11
 WHERE E11.SAL = E11.MAXSAL;