oracle分析函数系列之sum(col1) over(partition by col2 order by col3):实现分组汇总或递增汇总

语法:sum(col1) over(partition by col2 order by col3 )

准备数据:

   DEPT_ID   ENAME          SAL
1 1000            A                     2500
2 1000            B                    3500
3 1000           C                   1500
4 1000           D                    2000
5 2000            E                    2500
6 2000           F                    2000
7 2000           G                    3500

主要有四种情况:

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)。

1.有partition by有order by : 在partition by分组下,按照不同的order by col3实现递增汇总..

SQL>>select DEPT_ID,ENAME,SAL,sum(SAL) over(partition by dept_id order by ENAME) AS TOTAL from dept_sal

结果:按照部门分组,按名字排序实现递增汇总.

DEPT_ID ENAME SAL TOTAL

1 1000       A           3500   3500
2 1000       B           3500  7000
3 1000       C          1500   8500
4 1000       D          2000 10500
5 2000       E          2500   2500
6 2000       F          2000   4500
7 2000       G         3500    8000

如果col3重复会只加总一次(当然在本例中这种写法毫无意义):

SQL>> select DEPT_ID,ENAME,SAL,sum(SAL) over(partition by dept_id order by SAL) AS TOTAL from dept_sal

DEPT_ID ENAME SAL TOTAL

11000 C 1500 1500
2 1000 D 2000 3500
3 1000 A 3500 10500
4 1000 B 3500 10500
5 2000 F 2000 2000
6 2000 E 2500 4500
7 2000 G 3500 8000

2.有partition by无order by: 实现分组内所有数据的汇总

SQL>>select DEPT_ID,ENAME,SAL,sum(SAL) over(partition by dept_id) AS TOTAL from dept_sal

DEPT_ID ENAME SAL TOTAL
1 1000 A 3500 10500
2 1000 B 3500 10500
3 1000 C 1500 10500
4 1000 D 2000 10500
5 2000 E 2500 8000
6 2000 F 2000 8000
7 2000 G 3500 8000

3.无partition by有order by : 直接按order by 字段实现递增汇总

SQL>>select DEPT_ID,ENAME,SAL,sum(SAL) over(order by ENAME) AS TOTAL from dept_sal

DEPT_ID ENAME SAL TOTAL
1 1000 A 3500 3500
2 1000 B 3500 7000
3 1000 C 1500 8500
4 1000 D 2000 10500
5 2000 E 2500 13000
6 2000 F 2000 15000
7 2000 G 3500 18500

如果order by 的值相同,会进行汇总,但汇总后显示的值会是一样的,如下:

SQL>>select DEPT_ID,ENAME,SAL,sum(SAL) over(order by DEPT_ID) AS TOTAL from dept_sal

DEPT_ID ENAME SAL TOTAL
1 1000 A 3500 10500
2 1000 B 3500 10500
3 1000 C 1500 10500
4 1000 D 2000 10500
5 2000 E 2500 18500
6 2000 F 2000 18500
7 2000 G 3500 18500

4.无partition by无order by: 所有数据相加.

SQL>>select DEPT_ID,ENAME,SAL,sum(SAL) over() AS TOTAL from dept_sal

DEPT_ID ENAME SAL TOTAL
1 1000 A 3500 18500
2 1000 B 3500 18500
3 1000 C 1500 18500
4 1000 D 2000 18500
5 2000 E 2500 18500
6 2000 F 2000 18500
7 2000 G 3500 18500