PLSQL中over(partition by . order by .)的运用_SQL

PLSQL中over(partition by .. order by ..)的使用

SQL> select deptno,ename,sal
?? 2?? from emp
?? 3?? order by deptno;

DEPTNO ENAME????????? SAL
---------- ---------- ----------
?????? 10 CLARK????????? 2450
????????? KING????????? 5000
????????? MILLER?????????? 1300

?????? 20 SMITH????????? 800
????????? ADAMS????????? 1100
????????? FORD????????? 3000
????????? SCOTT????????? 3000
????????? JONES????????? 2975

?????? 30 ALLEN????????? 1600
????????? BLAKE????????? 2850
????????? MARTIN?????????? 1250
????????? JAMES????????? 950
????????? TURNER?????????? 1500
????????? WARD????????? 1250

已选择14行。

2.先来一个简单的，注意over(...)条件的不同，
使用 sum(sal) over (order by ename)... 查询员工的薪水“连续”求和,
注意over (order?? by ename)如果没有order by 子句，求和就不是“连续”的，
放在一起，体会一下不同之处：

SQL> select deptno,ename,sal,
?? 2?? sum(sal) over (order by ename) 连续求和,
?? 3?? sum(sal) over () 总和,??????????????? -- 此处sum(sal) over () 等同于sum(sal)
?? 4?? 100*round(sal/sum(sal) over (),4) "份额(%)"
?? 5?? from emp
?? 6?? /

DEPTNO ENAME????????? SAL 连续求和??? 总和份额(%)
---------- ---------- ---------- ---------- ---------- ----------
?????? 20 ADAMS????????? 1100??? 1100??? 29025??? 3.79
?????? 30 ALLEN????????? 1600??? 2700??? 29025??? 5.51
?????? 30 BLAKE????????? 2850??? 5550??? 29025??? 9.82
?????? 10 CLARK????????? 2450??? 8000??? 29025??? 8.44
?????? 20 FORD????????? 3000??? 11000??? 29025??? 10.34
?????? 30 JAMES????????? 950??? 11950??? 29025??? 3.27
?????? 20 JONES????????? 2975??? 14925??? 29025??? 10.25
?????? 10 KING????????? 5000??? 19925??? 29025??? 17.23
?????? 30 MARTIN?????????? 1250??? 21175??? 29025??? 4.31
?????? 10 MILLER?????????? 1300??? 22475??? 29025??? 4.48
?????? 20 SCOTT????????? 3000??? 25475??? 29025??? 10.34
?????? 20 SMITH????????? 800??? 26275??? 29025??? 2.76
?????? 30 TURNER?????????? 1500??? 27775??? 29025??? 5.17
?????? 30 WARD????????? 1250??? 29025??? 29025??? 4.31

已选择14行。

3.使用子分区查出各部门薪水连续的总和。注意按部门分区。注意over(...)条件的不同，
sum(sal) over (partition by deptno order by ename) 按部门“连续”求总和
sum(sal) over (partition by deptno) 按部门求总和
sum(sal) over (order by deptno，ename) 不按部门“连续”求总和
sum(sal) over () 不按部门，求所有员工总和，效果等同于sum(sal)。

SQL> select deptno,ename,sal,
?? 2?? sum(sal) over (partition by deptno order by ename) 部门连续求和,--各部门的薪水"连续"求和
?? 3?? sum(sal) over (partition by deptno) 部门总和,?? -- 部门统计的总和，同一部门总和不变
?? 4?? 100*round(sal/sum(sal) over (partition by deptno),4) "部门份额(%)",
?? 5?? sum(sal) over (order by deptno,ename) 连续求和, --所有部门的薪水"连续"求和
?? 6?? sum(sal) over () 总和,?? -- 此处sum(sal) over () 等同于sum(sal)，所有员工的薪水总和
?? 7?? 100*round(sal/sum(sal) over (),4) "总份额(%)"
?? 8?? from emp
?? 9?? /

DEPTNO ENAME SAL 部门连续求和部门总和部门份额(%) 连续求和总和?? 总份额(%)
------ ------ ----- ------------ ---------- ----------- ---------- ------ ----------
10 CLARK 2450?????? 2450??? 8750?????? 28??? 2450?? 29025??? 8.44
?? KING 5000?????? 7450??? 8750??? 57.14??? 7450?? 29025??? 17.23
?? MILLER?? 1300?????? 8750??? 8750??? 14.86??? 8750?? 29025??? 4.48

20 ADAMS 1100?????? 1100??? 10875??? 10.11??? 9850?? 29025??? 3.79
?? FORD 3000?????? 4100??? 10875??? 27.59??? 12850?? 29025??? 10.34
?? JONES 2975?????? 7075??? 10875??? 27.36??? 15825?? 29025??? 10.25
?? SCOTT 3000??????? 10075??? 10875??? 27.59??? 18825?? 29025??? 10.34
?? SMITH 800??????? 10875??? 10875??????? 7.36??? 19625?? 29025??? 2.76

30 ALLEN 1600?????? 1600??? 9400??? 17.02??? 21225?? 29025??? 5.51
?? BLAKE 2850?????? 4450??? 9400??? 30.32??? 24075?? 29025??? 9.82
?? JAMES 950?????? 5400??? 9400??? 10.11??? 25025?? 29025??? 3.27
?? MARTIN?? 1250?????? 6650??? 9400??????? 13.3??? 26275?? 29025??? 4.31
?? TURNER?? 1500?????? 8150??? 9400??? 15.96??? 27775?? 29025??? 5.17
?? WARD 1250?????? 9400??? 9400??????? 13.3??? 29025?? 29025??? 4.31

已选择14行。

4.来一个综合的例子，求和规则有按部门分区的，有不分区的例子
SQL> select deptno,ename,sal,sum(sal) over (partition by deptno order by sal) dept_sum,
?? 2?? sum(sal) over (order by deptno,sal) sum
?? 3?? from emp;

DEPTNO ENAME????????? SAL DEPT_SUM??????? SUM
---------- ---------- ---------- ---------- ----------
?????? 10 MILLER?????????? 1300??? 1300??? 1300
????????? CLARK????????? 2450??? 3750??? 3750
????????? KING????????? 5000??? 8750??? 8750

?????? 20 SMITH????????? 800??????? 800??? 9550
????????? ADAMS????????? 1100??? 1900??? 10650
????????? JONES????????? 2975??? 4875??? 13625
????????? SCOTT????????? 3000??? 10875??? 19625
????????? FORD????????? 3000??? 10875??? 19625

?????? 30 JAMES????????? 950??????? 950??? 20575
????????? WARD????????? 1250??? 3450??? 23075
????????? MARTIN?????????? 1250??? 3450??? 23075
????????? TURNER?????????? 1500??? 4950??? 24575
????????? ALLEN????????? 1600??? 6550??? 26175
????????? BLAKE????????? 2850??? 9400??? 29025

已选择14行。

5.来一个逆序的，即部门从大到小排列，部门里各员工的薪水从高到低排列，累计和的规则不变。

SQL> select deptno,ename,sal,
?? 2?? sum(sal) over (partition by deptno order by deptno desc,sal desc) dept_sum,
?? 3?? sum(sal) over (order by deptno desc,sal desc) sum
?? 4?? from emp;

DEPTNO ENAME????????? SAL DEPT_SUM??????? SUM
---------- ---------- ---------- ---------- ----------
?????? 30 BLAKE????????? 2850??? 2850??? 2850
????????? ALLEN????????? 1600??? 4450??? 4450
????????? TURNER?????????? 1500??? 5950??? 5950
????????? WARD????????? 1250??? 8450??? 8450
????????? MARTIN?????????? 1250??? 8450??? 8450
????????? JAMES????????? 950??? 9400??? 9400

?????? 20 SCOTT????????? 3000??? 3000??? 15400??????????? 3000??? 6000?? 15400
????????? FORD????????? 3000??? 6000??? 15400
????????? JONES????????? 2975??? 8975??? 18375
????????? ADAMS????????? 1100??? 10075??? 19475
????????? SMITH????????? 800??? 10875??? 20275

?????? 10 KING????????? 5000??? 5000??? 25275
????????? CLARK????????? 2450??? 7450??? 27725
????????? MILLER?????????? 1300??? 8750??? 29025

已选择14行。

6.体会：在"... from emp;"后面不要加order?? by 子句，使用的分析函数的(partition by deptno order by sal)
里已经有排序的语句了，如果再在句尾添加排序子句，一致倒罢了，不一致，结果就令人费劲了。如：

SQL> select deptno,ename,sal,sum(sal) over (partition by deptno order by sal) dept_sum,
?? 2?? sum(sal) over (order by deptno,sal) sum
?? 3?? from emp
?? 4?? order by deptno desc;

DEPTNO ENAME????????? SAL DEPT_SUM??????? SUM
---------- ---------- ---------- ---------- ----------
?????? 30 JAMES????????? 950??????? 950??? 20575
????????? WARD????????? 1250??? 3450??? 23075
????????? MARTIN?????????? 1250??? 3450??? 23075
????????? TURNER?????????? 1500??? 4950??? 24575
????????? ALLEN????????? 1600??? 6550??? 26175
????????? BLAKE????????? 2850??? 9400??? 29025

?????? 10 MILLER?????????? 1300??? 1300??? 1300
????????? CLARK????????? 2450??? 3750??? 3750
????????? KING????????? 5000??? 8750??? 8750

已选择14行

1 楼 helloqidi 2010-05-24

非常感谢，学习了