語法:sum(col1) over(partition by col2 order by col3 )
準備數據:
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
主要有四種情況:
sum(sal) over (partition by deptno order by ename) 按部門“連續”求總和
sum(sal) over (partition by deptno) 按部門求總和
sum(sal) over (order by deptno,ename) 不按部門“連續”求總和
sum(sal) over () 不按部門,求所有員工總和,效果等同於sum(sal)。
1.有partition by有order by : 在partition by分組下,按照不同的order by col3實現遞增彙總..
SQL>>select DEPT_ID,ENAME,SAL,sum(SAL) over(partition by dept_id order by ENAME) AS TOTAL from dept_sal
結果:按照部門分組,按名字排序實現遞增彙總.
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重複會只加總一次(當然在本例中這種寫法毫無意義):
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無order by: 實現分組內所有數據的彙總
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.無partition by有order by : 直接按order by 字段實現遞增彙總
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,會進行彙總,但彙總後顯示的值會是一樣的,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.無partition by無order by: 所有數據相加.
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
轉載自http://blog.csdn.net/rfb0204421/article/details/7672207