If NULLS LAST is left out of the final ORDER BY, the effect will be lost : NULLs Last « Analytical Functions « Oracle PL / 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>
           
       








Related examples in the same category

1.Control whether nulls are the highest or lowest in a group using NULLS LAST
2.NULLS LAST: place null value at the end
3.If the statement were without NULLS LAST, the values of the NVL'd nulls occur first
4.order by nulls last