Oracle PL/SQL/Analytical Functions/NULLs Last — различия между версиями
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Admin (обсуждение | вклад) м (1 версия) |
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Текущая версия на 09:55, 26 мая 2010
Содержание
- 1 Control whether nulls are the highest or lowest in a group using NULLS LAST
- 2 If NULLS LAST is left out of the final ORDER BY, the effect will be lost
- 3 If the statement were without NULLS LAST, the values of the NVL"d nulls occur first
- 4 NULLS LAST: place null value at the end
- 5 order by nulls last
Control whether nulls are the highest or lowest in a group using NULLS LAST
SQL> CREATE TABLE all_sales (
2 year INTEGER,
3 month INTEGER,
4 prd_type_id INTEGER,
5 emp_id INTEGER ,
6 amount NUMBER(8, 2)
7 );
Table created.
SQL>
SQL> insert into all_sales (YEAR,MONTH,PRD_TYPE_ID,EMP_ID,AMOUNT)
2 values(2006,1 ,1 ,21 ,16034.84);
1 row created.
SQL> insert into all_sales (YEAR,MONTH,PRD_TYPE_ID,EMP_ID,AMOUNT)
2 values(2006,2 ,1 ,21 ,15644.65);
1 row created.
SQL> insert into all_sales (YEAR,MONTH,PRD_TYPE_ID,EMP_ID,AMOUNT)
2 values(2006,3 ,2 ,21 ,20167.83);
1 row created.
SQL> insert into all_sales (YEAR,MONTH,PRD_TYPE_ID,EMP_ID,AMOUNT)
2 values(2006,4 ,2 ,21 ,25056.45);
1 row created.
SQL> insert into all_sales (YEAR,MONTH,PRD_TYPE_ID,EMP_ID,AMOUNT)
2 values(2006,5 ,2 ,21 ,NULL);
1 row created.
SQL> insert into all_sales (YEAR,MONTH,PRD_TYPE_ID,EMP_ID,AMOUNT)
2 values(2006,6 ,1 ,21 ,15564.66);
1 row created.
SQL> insert into all_sales (YEAR,MONTH,PRD_TYPE_ID,EMP_ID,AMOUNT)
2 values(2006,7 ,1 ,21 ,15644.65);
1 row created.
SQL> insert into all_sales (YEAR,MONTH,PRD_TYPE_ID,EMP_ID,AMOUNT)
2 values(2006,8 ,1 ,21 ,NULL);
1 row created.
SQL> insert into all_sales (YEAR,MONTH,PRD_TYPE_ID,EMP_ID,AMOUNT)
2 values(2006,9 ,1 ,21 ,19654.57);
1 row created.
SQL> insert into all_sales (YEAR,MONTH,PRD_TYPE_ID,EMP_ID,AMOUNT)
2 values(2006,10 ,1 ,21 ,21764.19);
1 row created.
SQL> insert into all_sales (YEAR,MONTH,PRD_TYPE_ID,EMP_ID,AMOUNT)
2 values(2006,11 ,1 ,21 ,13026.73);
1 row created.
SQL> insert into all_sales (YEAR,MONTH,PRD_TYPE_ID,EMP_ID,AMOUNT)
2 values(2006,12 ,2 ,21 ,10034.64);
1 row created.
SQL> insert into all_sales (YEAR,MONTH,PRD_TYPE_ID,EMP_ID,AMOUNT)
2 values(2005,1 ,2 ,22 ,16634.84);
1 row created.
SQL> insert into all_sales (YEAR,MONTH,PRD_TYPE_ID,EMP_ID,AMOUNT)
2 values(2005,1 ,2 ,21 ,26034.84);
1 row created.
SQL> insert into all_sales (YEAR,MONTH,PRD_TYPE_ID,EMP_ID,AMOUNT)
2 values(2005,2 ,1 ,21 ,12644.65);
1 row created.
SQL> insert into all_sales (YEAR,MONTH,PRD_TYPE_ID,EMP_ID,AMOUNT)
2 values(2005,3 ,1 ,21 ,NULL);
1 row created.
SQL> insert into all_sales (YEAR,MONTH,PRD_TYPE_ID,EMP_ID,AMOUNT)
2 values(2005,4 ,1 ,21 ,25026.45);
1 row created.
SQL> insert into all_sales (YEAR,MONTH,PRD_TYPE_ID,EMP_ID,AMOUNT)
2 values(2005,5 ,1 ,21 ,17212.66);
1 row created.
SQL> insert into all_sales (YEAR,MONTH,PRD_TYPE_ID,EMP_ID,AMOUNT)
2 values(2005,6 ,1 ,21 ,15564.26);
1 row created.
SQL> insert into all_sales (YEAR,MONTH,PRD_TYPE_ID,EMP_ID,AMOUNT)
2 values(2005,7 ,2 ,21 ,62654.82);
1 row created.
SQL> insert into all_sales (YEAR,MONTH,PRD_TYPE_ID,EMP_ID,AMOUNT)
2 values(2005,8 ,2 ,21 ,26434.82);
1 row created.
SQL> insert into all_sales (YEAR,MONTH,PRD_TYPE_ID,EMP_ID,AMOUNT)
2 values(2005,9 ,2 ,21 ,15644.65);
1 row created.
SQL> insert into all_sales (YEAR,MONTH,PRD_TYPE_ID,EMP_ID,AMOUNT)
2 values(2005,10 ,2 ,21 ,21264.19);
1 row created.
SQL> insert into all_sales (YEAR,MONTH,PRD_TYPE_ID,EMP_ID,AMOUNT)
2 values(2005,11 ,1 ,21 ,13026.73);
1 row created.
SQL> insert into all_sales (YEAR,MONTH,PRD_TYPE_ID,EMP_ID,AMOUNT)
2 values(2005,12 ,1 ,21 ,NULL);
1 row created.
SQL>
SQL> select * from all_sales;
YEAR MONTH PRD_TYPE_ID EMP_ID AMOUNT
---------- ---------- ----------- ---------- ----------
2006 1 1 21 16034.84
2006 2 1 21 15644.65
2006 3 2 21 20167.83
2006 4 2 21 25056.45
2006 5 2 21
2006 6 1 21 15564.66
2006 7 1 21 15644.65
2006 8 1 21
2006 9 1 21 19654.57
2006 10 1 21 21764.19
2006 11 1 21 13026.73
2006 12 2 21 10034.64
2005 1 2 22 16634.84
2005 1 2 21 26034.84
2005 2 1 21 12644.65
2005 3 1 21
2005 4 1 21 25026.45
2005 5 1 21 17212.66
2005 6 1 21 15564.26
2005 7 2 21 62654.82
2005 8 2 21 26434.82
2005 9 2 21 15644.65
2005 10 2 21 21264.19
2005 11 1 21 13026.73
2005 12 1 21
25 rows selected.
SQL>
SQL> --Control whether nulls are the highest or lowest in a group using NULLS LAST
SQL>
SQL> SELECT
2 prd_type_id, SUM(amount),
3 RANK() OVER (ORDER BY SUM(amount) DESC NULLS LAST) AS rank,
4 DENSE_RANK() OVER (ORDER BY SUM(amount) DESC NULLS LAST) AS
5 dense_rank
6 FROM all_sales
7 GROUP BY prd_type_id
8 ORDER BY prd_type_id;
PRD_TYPE_ID SUM(AMOUNT) RANK DENSE_RANK
----------- ----------- ---------- ----------
1 200809.04 2 2
2 223927.08 1 1
SQL>
SQL> drop table all_sales;
Table dropped.
SQL>
SQL>
If NULLS LAST is left out of the final ORDER BY, the effect will be lost
SQL>
SQL> -- create demo table
SQL> create table Employee(
2 empno Number(3) NOT NULL, -- Employee ID
3 ename VARCHAR2(10 BYTE), -- Employee Name
4 hireDate DATE, -- Date Employee Hired
5 orig_salary Number(8,2), -- Orignal Salary
6 curr_salary Number(8,2), -- Current Salary
7 region VARCHAR2(1 BYTE) -- Region where employeed
8 )
9 /
Table created.
SQL>
SQL>
SQL> -- prepare data for employee table
SQL> insert into Employee(empno, ename, hireDate, orig_salary, curr_salary, region)
2 values(122,"Alison",to_date("19960321","YYYYMMDD"), 45000, NULL, "E")
3 /
1 row created.
SQL> insert into Employee(empno, ename, hireDate, orig_salary, curr_salary, region)
2 values(123, "James",to_date("19781212","YYYYMMDD"), 23000, 32000, "W")
3 /
1 row created.
SQL> insert into Employee(empno, ename, hireDate, orig_salary, curr_salary, region)
2 values(104,"Celia",to_date("19821024","YYYYMMDD"), NULL, 58000, "E")
3 /
1 row created.
SQL> insert into Employee(empno, ename, hireDate, orig_salary, curr_salary, region)
2 values(105,"Robert",to_date("19840115","YYYYMMDD"), 31000, NULL, "W")
3 /
1 row created.
SQL> insert into Employee(empno, ename, hireDate, orig_salary, curr_salary, region)
2 values(116,"Linda", to_date("19870730","YYYYMMDD"), NULL, 53000, "E")
3 /
1 row created.
SQL> insert into Employee(empno, ename, hireDate, orig_salary, curr_salary, region)
2 values(117,"David", to_date("19901231","YYYYMMDD"), 78000, NULL, "W")
3 /
1 row created.
SQL> insert into Employee(empno, ename, hireDate, orig_salary, curr_salary, region)
2 values(108,"Jode", to_date("19960917","YYYYMMDD"), 21000, 29000, "E")
3 /
1 row created.
SQL>
SQL> -- display data in the table
SQL> select * from Employee
2 /
Hit a key to continue
EMPNO ENAME HIREDATE ORIG_SALARY CURR_SALARY R
---------- ---------- --------- ----------- ----------- -
122 Alison 21-MAR-96 45000 E
123 James 12-DEC-78 23000 32000 W
104 Celia 24-OCT-82 58000 E
105 Robert 15-JAN-84 31000 W
116 Linda 30-JUL-87 53000 E
117 David 31-DEC-90 78000 W
108 Jode 17-SEP-96 21000 29000 E
7 rows selected.
SQL>
SQL>
SQL>
SQL> -- If NULLS LAST is left out of the final ORDER BY, the effect will be lost.
SQL>
SQL> SELECT empno, ename, curr_salary,
2 RANK()
3 OVER(ORDER BY curr_salary desc) salary
4 FROM employee
5 ORDER BY curr_salary desc;
Hit a key to continue
EMPNO ENAME CURR_SALARY SALARY
---------- ---------- ----------- ----------
122 Alison 1
105 Robert 1
117 David 1
104 Celia 58000 4
116 Linda 53000 5
123 James 32000 6
108 Jode 29000 7
7 rows selected.
SQL>
SQL>
SQL> -- clean the table
SQL> drop table Employee;
Table dropped.
SQL>
SQL>
If the statement were without NULLS LAST, the values of the NVL"d nulls occur first
SQL>
SQL> -- create demo table
SQL> create table Employee(
2 empno Number(3) NOT NULL, -- Employee ID
3 ename VARCHAR2(10 BYTE), -- Employee Name
4 hireDate DATE, -- Date Employee Hired
5 orig_salary Number(8,2), -- Orignal Salary
6 curr_salary Number(8,2), -- Current Salary
7 region VARCHAR2(1 BYTE) -- Region where employeed
8 )
9 /
Table created.
SQL>
SQL>
SQL> -- prepare data for employee table
SQL> insert into Employee(empno, ename, hireDate, orig_salary, curr_salary, region)
2 values(122,"Alison",to_date("19960321","YYYYMMDD"), 45000, NULL, "E")
3 /
1 row created.
SQL> insert into Employee(empno, ename, hireDate, orig_salary, curr_salary, region)
2 values(123, "James",to_date("19781212","YYYYMMDD"), 23000, 32000, "W")
3 /
1 row created.
SQL> insert into Employee(empno, ename, hireDate, orig_salary, curr_salary, region)
2 values(104,"Celia",to_date("19821024","YYYYMMDD"), NULL, 58000, "E")
3 /
1 row created.
SQL> insert into Employee(empno, ename, hireDate, orig_salary, curr_salary, region)
2 values(105,"Robert",to_date("19840115","YYYYMMDD"), 31000, NULL, "W")
3 /
1 row created.
SQL> insert into Employee(empno, ename, hireDate, orig_salary, curr_salary, region)
2 values(116,"Linda", to_date("19870730","YYYYMMDD"), NULL, 53000, "E")
3 /
1 row created.
SQL> insert into Employee(empno, ename, hireDate, orig_salary, curr_salary, region)
2 values(117,"David", to_date("19901231","YYYYMMDD"), 78000, NULL, "W")
3 /
1 row created.
SQL> insert into Employee(empno, ename, hireDate, orig_salary, curr_salary, region)
2 values(108,"Jode", to_date("19960917","YYYYMMDD"), 21000, 29000, "E")
3 /
1 row created.
SQL>
SQL> -- display data in the table
SQL> select * from Employee
2 /
EMPNO ENAME HIREDATE ORIG_SALARY CURR_SALARY R
---------- ---------- --------- ----------- ----------- -
122 Alison 21-MAR-96 45000 E
123 James 12-DEC-78 23000 32000 W
104 Celia 24-OCT-82 58000 E
105 Robert 15-JAN-84 31000 W
116 Linda 30-JUL-87 53000 E
117 David 31-DEC-90 78000 W
108 Jode 17-SEP-96 21000 29000 E
7 rows selected.
SQL>
SQL>
SQL>
SQL>
SQL>
SQL> SELECT empno, ename, NVL(curr_salary,44444),
2 RANK()
3 OVER(ORDER BY NVL(curr_salary,44444) desc) salary
4 FROM employee
5 ORDER BY curr_salary desc;
EMPNO ENAME NVL(CURR_SALARY,44444) SALARY
---------- ---------- ---------------------- ----------
105 Robert 44444 3
117 David 44444 3
122 Alison 44444 3
104 Celia 58000 1
116 Linda 53000 2
123 James 32000 6
108 Jode 29000 7
7 rows selected.
SQL>
SQL>
SQL>
SQL>
SQL> -- clean the table
SQL> drop table Employee;
Table dropped.
SQL>
SQL>
NULLS LAST: place null value at the end
SQL>
SQL> -- create demo table
SQL> create table Employee(
2 empno Number(3) NOT NULL, -- Employee ID
3 ename VARCHAR2(10 BYTE), -- Employee Name
4 hireDate DATE, -- Date Employee Hired
5 orig_salary Number(8,2), -- Orignal Salary
6 curr_salary Number(8,2), -- Current Salary
7 region VARCHAR2(1 BYTE) -- Region where employeed
8 )
9 /
Table created.
SQL>
SQL>
SQL> -- prepare data for employee table
SQL> insert into Employee(empno, ename, hireDate, orig_salary, curr_salary, region)
2 values(122,"Alison",to_date("19960321","YYYYMMDD"), 45000, NULL, "E")
3 /
1 row created.
SQL> insert into Employee(empno, ename, hireDate, orig_salary, curr_salary, region)
2 values(123, "James",to_date("19781212","YYYYMMDD"), 23000, 32000, "W")
3 /
1 row created.
SQL> insert into Employee(empno, ename, hireDate, orig_salary, curr_salary, region)
2 values(104,"Celia",to_date("19821024","YYYYMMDD"), NULL, 58000, "E")
3 /
1 row created.
SQL> insert into Employee(empno, ename, hireDate, orig_salary, curr_salary, region)
2 values(105,"Robert",to_date("19840115","YYYYMMDD"), 31000, NULL, "W")
3 /
1 row created.
SQL> insert into Employee(empno, ename, hireDate, orig_salary, curr_salary, region)
2 values(116,"Linda", to_date("19870730","YYYYMMDD"), NULL, 53000, "E")
3 /
1 row created.
SQL> insert into Employee(empno, ename, hireDate, orig_salary, curr_salary, region)
2 values(117,"David", to_date("19901231","YYYYMMDD"), 78000, NULL, "W")
3 /
1 row created.
SQL> insert into Employee(empno, ename, hireDate, orig_salary, curr_salary, region)
2 values(108,"Jode", to_date("19960917","YYYYMMDD"), 21000, 29000, "E")
3 /
1 row created.
SQL>
SQL> -- display data in the table
SQL> select * from Employee
2 /
Hit a key to continue
EMPNO ENAME HIREDATE ORIG_SALARY CURR_SALARY R
---------- ---------- --------- ----------- ----------- -
122 Alison 21-MAR-96 45000 E
123 James 12-DEC-78 23000 32000 W
104 Celia 24-OCT-82 58000 E
105 Robert 15-JAN-84 31000 W
116 Linda 30-JUL-87 53000 E
117 David 31-DEC-90 78000 W
108 Jode 17-SEP-96 21000 29000 E
7 rows selected.
SQL>
SQL>
SQL>
SQL>
SQL> -- When nulls are present, there is an option to place nulls first or last with the analytical function.
SQL>
SQL> SELECT empno, ename, curr_salary,
2 ROW_NUMBER() OVER(ORDER BY curr_salary NULLS LAST)
3 salary
4 FROM employee
5 ORDER BY curr_salary;
Hit a key to continue
EMPNO ENAME CURR_SALARY SALARY
---------- ---------- ----------- ----------
108 Jode 29000 1
123 James 32000 2
116 Linda 53000 3
104 Celia 58000 4
117 David 5
122 Alison 6
105 Robert 7
7 rows selected.
SQL>
SQL>
SQL> -- clean the table
SQL> drop table Employee;
Table dropped.
SQL>
SQL>
order by nulls last
SQL>
SQL>
SQL> CREATE TABLE EMP (EMPNO NUMBER(4) NOT NULL,
2 ENAME VARCHAR2(10),
3 JOB VARCHAR2(9),
4 MGR NUMBER(4),
5 HIREDATE DATE,
6 SAL NUMBER(7, 2),
7 COMM NUMBER(7, 2),
8 DEPTNO NUMBER(2));
Table created.
SQL>
SQL> INSERT INTO EMP VALUES (7369, "SMITH", "CLERK", 7902, TO_DATE("17-DEC-1980", "DD-MON-YYYY"), 800, NULL, 20);
1 row created.
SQL> INSERT INTO EMP VALUES (7499, "ALLEN", "SALESMAN", 7698, TO_DATE("20-FEB-1981", "DD-MON-YYYY"), 1600, 300, 30);
1 row created.
SQL> INSERT INTO EMP VALUES (7521, "WARD", "SALESMAN", 7698, TO_DATE("22-FEB-1981", "DD-MON-YYYY"), 1250, 500, 30);
1 row created.
SQL> INSERT INTO EMP VALUES (7566, "JONES", "MANAGER", 7839, TO_DATE("2-APR-1981", "DD-MON-YYYY"), 2975, NULL, 20);
1 row created.
SQL> INSERT INTO EMP VALUES (7654, "MARTIN", "SALESMAN", 7698,TO_DATE("28-SEP-1981", "DD-MON-YYYY"), 1250, 1400, 30);
1 row created.
SQL> INSERT INTO EMP VALUES (7698, "BLAKE", "MANAGER", 7839,TO_DATE("1-MAY-1981", "DD-MON-YYYY"), 2850, NULL, 30);
1 row created.
SQL> INSERT INTO EMP VALUES (7782, "CLARK", "MANAGER", 7839,TO_DATE("9-JUN-1981", "DD-MON-YYYY"), 2450, NULL, 10);
1 row created.
SQL> INSERT INTO EMP VALUES (7788, "SCOTT", "ANALYST", 7566,TO_DATE("09-DEC-1982", "DD-MON-YYYY"), 3000, NULL, 20);
1 row created.
SQL> INSERT INTO EMP VALUES (7839, "KING", "PRESIDENT", NULL,TO_DATE("17-NOV-1981", "DD-MON-YYYY"), 5000, NULL, 10);
1 row created.
SQL> INSERT INTO EMP VALUES (7844, "TURNER", "SALESMAN", 7698,TO_DATE("8-SEP-1981", "DD-MON-YYYY"), 1500, 0, 30);
1 row created.
SQL> INSERT INTO EMP VALUES (7876, "ADAMS", "CLERK", 7788,TO_DATE("12-JAN-1983", "DD-MON-YYYY"), 1100, NULL, 20);
1 row created.
SQL> INSERT INTO EMP VALUES (7900, "JAMES", "CLERK", 7698,TO_DATE("3-DEC-1981", "DD-MON-YYYY"), 950, NULL, 30);
1 row created.
SQL> INSERT INTO EMP VALUES (7902, "FORD", "ANALYST", 7566,TO_DATE("3-DEC-1981", "DD-MON-YYYY"), 3000, NULL, 20);
1 row created.
SQL> INSERT INTO EMP VALUES (7934, "MILLER", "CLERK", 7782,TO_DATE("23-JAN-1982", "DD-MON-YYYY"), 1300, NULL, 10);
1 row created.
SQL>
SQL> select * from emp;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
-------- ---------- --------- -------- --------- -------- -------- ------
7369.00 SMITH CLERK 7902.00 17-DEC-80 800.00 20
7499.00 ALLEN SALESMAN 7698.00 20-FEB-81 1600.00 300.00 30
7521.00 WARD SALESMAN 7698.00 22-FEB-81 1250.00 500.00
7566.00 JONES MANAGER 7839.00 02-APR-81 2975.00 20
7654.00 MARTIN SALESMAN 7698.00 28-SEP-81 1250.00 1400.00 30
7698.00 BLAKE MANAGER 7839.00 01-MAY-81 2850.00
7782.00 CLARK MANAGER 7839.00 09-JUN-81 2450.00 10
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
-------- ---------- --------- -------- --------- -------- -------- ------
7788.00 SCOTT ANALYST 7566.00 09-DEC-82 3000.00 20
7839.00 KING PRESIDENT 17-NOV-81 5000.00 10
7844.00 TURNER SALESMAN 7698.00 08-SEP-81 1500.00 .00 30
7876.00 ADAMS CLERK 7788.00 12-JAN-83 1100.00 20
7900.00 JAMES CLERK 7698.00 03-DEC-81 950.00 30
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
-------- ---------- --------- -------- --------- -------- -------- ------
7902.00 FORD ANALYST 7566.00 03-DEC-81 3000.00 20
7934.00 MILLER CLERK 7782.00 23-JAN-82 1300.00 10
14 rows selected.
SQL>
SQL>
SQL>
SQL> select ename, comm from emp order by comm desc nulls last
2 /
ENAME COMM
---------- --------
MARTIN 1400.00
WARD 500.00
ALLEN 300.00
TURNER .00
SCOTT
KING
ADAMS
JAMES
FORD
MILLER
BLAKE
ENAME COMM
---------- --------
JONES
SMITH
CLARK
14 rows selected.
SQL>
SQL> drop table emp;
Table dropped.
SQL>