Count distinct with group by : Group By « Query Select « Oracle PL/SQL Tutorial

SQL> create table offerings
  2  ( course     VARCHAR2(6)
  3  , begindate  DATE
  4  , Coder      NUMBER(4)
  5  , location   VARCHAR2(8)
  6  ) ;

Table created.

SQL> insert into offerings values ('SQL',date '2009-04-12',13,'DALLAS' );

1 row created.

SQL> insert into offerings values ('OAU',date '2009-08-10',4,'CHICAGO');

1 row created.

SQL> insert into offerings values ('SQL',date '2009-10-04',1,'SEATTLE');

1 row created.

SQL> insert into offerings values ('SQL',date '2009-12-13',1,'DALLAS' );

1 row created.

SQL> insert into offerings values ('JAV',date '2009-12-13',4,'SEATTLE');

1 row created.

SQL> insert into offerings values ('XML',date '2000-02-03',1,'DALLAS' );

1 row created.

SQL> insert into offerings values ('JAV',date '2000-02-01',11,'DALLAS' );

1 row created.

SQL> insert into offerings values ('PLS',date '2000-09-11',8,'DALLAS' );

1 row created.

SQL> insert into offerings values ('XML',date '2000-09-18',NULL,'SEATTLE');

1 row created.

SQL> insert into offerings values ('OAU',date '2000-09-27',13,'DALLAS' );

1 row created.

SQL> insert into offerings values ('ERM',date '2001-01-15',NULL, NULL    );

1 row created.

SQL> insert into offerings values ('PRO',date '2001-02-19',NULL,'DALLAS' );

1 row created.

SQL> insert into offerings values ('RSD',date '2001-02-24',8,'CHICAGO');

1 row created.

SQL>
SQL> select Coder
  2  ,      count(distinct course)
  3  ,      count(*)
  4  from   offerings
  5  group  by Coder;

     CODER COUNT(DISTINCTCOURSE)   COUNT(*)
---------- --------------------- ----------
         1                     2          3
         4                     2          2
         8                     2          2
        11                     1          1
        13                     2          2
                               3          3

6 rows selected.

SQL>
SQL>
SQL> drop table offerings;

Table dropped.

2.5.Group By
	2.5.1.	Using Multiple Columns in a Group
	2.5.2.	GROUP by with NULL value
	2.5.3.	Use the aggregate functions with the GROUP BY clause
	2.5.4.	By default, GROUP BY sorts the rows in ascending order
	2.5.5.	Using the ORDER BY Clause to Sort Groups
	2.5.6.	You don't have to include the columns used in the GROUP BY clause in your SELECT clause
	2.5.7.	GROUP BY used on a column without the column name appearing in the result set
	2.5.8.	Any row-level variable (i.e., a column name) in the result set must be mentioned in the GROUP BY clause for the query to make sense.
	2.5.9.	Grouping at Multiple Levels
	2.5.10.	ORA-00979: not a GROUP BY expression
	2.5.11.	Getting Values and Subtotals in One Go
	2.5.12.	Getting Values and Subtotals in One Go with COALESCE
	2.5.13.	Getting Values and Subtotals in One Go with UNION
	2.5.14.	Group all ids with averager value more than
	2.5.15.	Group and count employeem and display only if its count is more than 4
	2.5.16.	Count employee, group by department id and job title
	2.5.17.	Count and group by department id
	2.5.18.	Count distinct with group by
	2.5.19.	Born after '1960-01-01', group by department number with count(*) >= 4;
	2.5.20.	Group by case