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Oracle 序號函數

width clerk spa 每一個 order mit sco rom group

Oracle提供的序號函數:
以emp表為例:
1: rownum 最簡單的序號 但是在order by之前就確定值.
select rownum,t.* from emp t order by ename

行數 ROWNUM EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
1 11 7876 ADAMS CLERK 7788 1987-5-23 1100   20
2 2 7499 ALLEN SALESMAN 7698 1981-2-20 1600 300 30
3 6 7698 BLAKE MANAGER 7839 1981-5-1 2850   30
4 7 7782 CLARK MANAGER 7839 1981-6-9 2450   10
5 13 7902 FORD ANALYST 7566 1981-12-3 3000   20
6 12 7900 JAMES CLERK 7698 1981-12-3 950   30
7 4 7566 JONES MANAGER 7839 1981-4-2 2975   20
8 9 7839 KING PRESIDENT   1981-11-17 5000   10
9 5 7654 MARTIN SALESMAN 7698 1981-9-28 1250 1400 30
10 14 7934 MILLER CLERK 7782 1982-1-23 1300   10
11 8 7788 SCOTT ANALYST 7566 1987-4-19 3000   20
12 1 7369 SMITH CLERK 7902 1980-12-17 800   20
13 10 7844 TURNER SALESMAN 7698 1981-9-8 1500 0 30
14 3 7521 WARD SALESMAN 7698 1981-2-22 1250 500 30


2: row_number() over( order by 字段名1,字段名2,...字段名n ) 先排序再確定序號.
select row_number() over( order by ename ) as rm, t.* from emp t

行數 RM EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
1 1 7876 ADAMS CLERK 7788 1987-5-23 1100   20
2 2 7499 ALLEN SALESMAN 7698 1981-2-20 1600 300 30
3 3 7698 BLAKE MANAGER 7839 1981-5-1 2850   30
4 4 7782 CLARK MANAGER 7839 1981-6-9 2450   10
5 5 7902 FORD ANALYST 7566 1981-12-3 3000   20
6 6 7900 JAMES CLERK 7698 1981-12-3 950   30
7 7 7566 JONES MANAGER 7839 1981-4-2 2975   20
8 8 7839 KING PRESIDENT   1981-11-17 5000   10
9 9 7654 MARTIN SALESMAN 7698 1981-9-28 1250 1400 30
10 10 7934 MILLER CLERK 7782 1982-1-23 1300   10
11 11 7788 SCOTT ANALYST 7566 1987-4-19 3000   20
12 12 7369 SMITH CLERK 7902 1980-12-17 800   20
13 13 7844 TURNER SALESMAN 7698 1981-9-8 1500 0 30
14 14 7521 WARD SALESMAN 7698 1981-2-22 1250 500 30



3: 和上面的不同之處在於PARTITION分區.在每一個小分區內部取序號.
select row_number() over(PARTITION BY deptno order by sal ) as rm, t.* from emp t

行數 RM EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
1 1 7934 MILLER CLERK 7782 1982-1-23 1300   10
2 2 7782 CLARK MANAGER 7839 1981-6-9 2450   10
3 3 7839 KING PRESIDENT   1981-11-17 5000   10
4 1 7369 SMITH CLERK 7902 1980-12-17 800   20
5 2 7876 ADAMS CLERK 7788 1987-5-23 1100   20
6 3 7566 JONES MANAGER 7839 1981-4-2 2975   20
7 4 7788 SCOTT ANALYST 7566 1987-4-19 3000   20
8 5 7902 FORD ANALYST 7566 1981-12-3 3000   20
9 1 7900 JAMES CLERK 7698 1981-12-3 950   30
10 2 7521 WARD SALESMAN 7698 1981-2-22 1250 500 30
11 3 7654 MARTIN SALESMAN 7698 1981-9-28 1250 1400 30
12 4 7844 TURNER SALESMAN 7698 1981-9-8 1500 0 30
13 5 7499 ALLEN SALESMAN 7698 1981-2-20 1600 300 30
14 6 7698 BLAKE MANAGER 7839 1981-5-1 2850   30



4: rank()在這裏表示針對每個部門員工的工資取序號.
select rank() over(PARTITION BY deptno order by sal ) as rnk, t.* from emp t;

行數 RNK EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
1 1 7934 MILLER CLERK 7782 1982-1-23 1300   10
2 2 7782 CLARK MANAGER 7839 1981-6-9 2450   10
3 3 7839 KING PRESIDENT   1981-11-17 5000   10
4 1 7369 SMITH CLERK 7902 1980-12-17 800   20
5 2 7876 ADAMS CLERK 7788 1987-5-23 1100   20
6 3 7566 JONES MANAGER 7839 1981-4-2 2975   20
7 4 7788 SCOTT ANALYST 7566 1987-4-19 3000   20
8 4 7902 FORD ANALYST 7566 1981-12-3 3000   20
9 1 7900 JAMES CLERK 7698 1981-12-3 950   30
10 2 7521 WARD SALESMAN 7698 1981-2-22 1250 500 30
11 2 7654 MARTIN SALESMAN 7698 1981-9-28 1250 1400 30
12 4 7844 TURNER SALESMAN 7698 1981-9-8 1500 0 30
13 5 7499 ALLEN SALESMAN 7698 1981-2-20 1600 300 30
14 6 7698 BLAKE MANAGER 7839 1981-5-1 2850   30



5: 從例子中可以看到dense_rank()和rank()的唯一區別就是:
dense_rank()中並列第二名後是第三名.
rank()中並列第二名後是第四名.
select dense_rank() over(PARTITION BY deptno order by sal ) as dense_rnk, t.* from emp t;

行數 DENSE_RNK EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
1 1 7934 MILLER CLERK 7782 1982-1-23 1300   10
2 2 7782 CLARK MANAGER 7839 1981-6-9 2450   10
3 3 7839 KING PRESIDENT   1981-11-17 5000   10
4 1 7369 SMITH CLERK 7902 1980-12-17 800   20
5 2 7876 ADAMS CLERK 7788 1987-5-23 1100   20
6 3 7566 JONES MANAGER 7839 1981-4-2 2975   20
7 4 7788 SCOTT ANALYST 7566 1987-4-19 3000   20
8 4 7902 FORD ANALYST 7566 1981-12-3 3000   20
9 1 7900 JAMES CLERK 7698 1981-12-3 950   30
10 2 7521 WARD SALESMAN 7698 1981-2-22 1250 500 30
11 2 7654 MARTIN SALESMAN 7698 1981-9-28 1250 1400 30
12 3 7844 TURNER SALESMAN 7698 1981-9-8 1500 0 30
13 4 7499 ALLEN SALESMAN 7698 1981-2-20 1600 300 30
14 5 7698 BLAKE MANAGER 7839 1981-5-1 2850   30

Oracle 序號函數