Count all employees by even/odd employee id : COUNT « Aggregate Functions « Oracle PL/SQL Tutorial

SQL>
SQL> create table emp
  2  ( empno      NUMBER(4)    constraint E_PK primary key
  3  , ename      VARCHAR2(8)
  4  , init       VARCHAR2(5)
  5  , job        VARCHAR2(8)
  6  , mgr        NUMBER(4)
  7  , bdate      DATE
  8  , sal        NUMBER(6,2)
  9  , comm       NUMBER(6,2)
 10  , deptno     NUMBER(2)    default 10
 11  ) ;

Table created.

SQL> insert into emp values(1,'Tom','N',   'TRAINER', 13,date '1965-12-17',  800 , NULL,  20);

1 row created.

SQL> insert into emp values(2,'Jack','JAM', 'Tester',6,date '1961-02-20',  1600, 300,   30);

1 row created.

SQL> insert into emp values(3,'Wil','TF' ,  'Tester',6,date '1962-02-22',  1250, 500,   30);

1 row created.

SQL> insert into emp values(4,'Jane','JM',  'Designer', 9,date '1967-04-02',  2975, NULL,  20);

1 row created.

SQL> insert into emp values(5,'Mary','P',  'Tester',6,date '1956-09-28',  1250, 1400,  30);

1 row created.

SQL> insert into emp values(6,'Black','R',   'Designer', 9,date '1963-11-01',  2850, NULL,  30);

1 row created.

SQL> insert into emp values(7,'Chris','AB',  'Designer', 9,date '1965-06-09',  2450, NULL,  10);

1 row created.

SQL> insert into emp values(8,'Smart','SCJ', 'TRAINER', 4,date '1959-11-26',  3000, NULL,  20);

1 row created.

SQL> insert into emp values(9,'Peter','CC',   'Designer',NULL,date '1952-11-17',  5000, NULL,  10);

1 row created.

SQL> insert into emp values(10,'Take','JJ', 'Tester',6,date '1968-09-28',  1500, 0,     30);

1 row created.

SQL> insert into emp values(11,'Ana','AA',  'TRAINER', 8,date '1966-12-30',  1100, NULL,  20);

1 row created.

SQL> insert into emp values(12,'Jane','R',   'Manager',   6,date '1969-12-03',  800 , NULL,  30);

1 row created.

SQL> insert into emp values(13,'Fake','MG',   'TRAINER', 4,date '1959-02-13',  3000, NULL,  20);

1 row created.

SQL> insert into emp values(14,'Mike','TJA','Manager',   7,date '1962-01-23',  1300, NULL,  10);

1 row created.

SQL>
SQL> select case mod(empno,2)
  2              when 0 then 'EVEN '
  3                     else 'ODD  '
  4         end  as empno
  5  ,      sum(sal)
  6  from   emp
  7  group  by mod(empno,2);

EMPNO   SUM(SAL)
----- ----------
EVEN       14025
ODD        14850

SQL>
SQL> drop table emp;

Table dropped.

12.3.COUNT
	12.3.1.	COUNT(x) gets the number of rows returned by a query.
	12.3.2.	Passes ROWID to COUNT() and gets the number of rows
	12.3.3.	COUNT() with null
	12.3.4.	Using an aggregate with the GROUP BY clause to count by city
	12.3.5.	COUNT(1) from a table
	12.3.6.	Count column with table alias
	12.3.7.	Count distinct column value
	12.3.8.	Compare the difference between count(*) and count(distinct course)
	12.3.9.	Count employees in the same department
	12.3.10.	JOIN with AND and aggregate function
	12.3.11.	count(*) - count(onhand)
	12.3.12.	count(*) vs count(column name)
	12.3.13.	Count all employees by even/odd employee id
	12.3.14.	Count date field value, and calculation