Group by case : Group By « Query Select « Oracle PL/SQL Tutorial

SQL> create table emp(
  2           emp_no                 integer         primary key,
  3           lastname               varchar2(20)    not null,
  4           firstname              varchar2(15)    not null,
  5           midinit                varchar2(1),
  6           street                 varchar2(30),
  7           city                   varchar2(20),
  8           state                  varchar2(2),
  9           zip                    varchar2(5),
 10           shortZipCode                   varchar2(4),
 11           area_code              varchar2(3),
 12           phone                  varchar2(8),
 13           salary                 number(5,2),
 14           birthdate              date,
 15           startDate              date,
 16           title                  varchar2(20),
 17           dept_no                integer,
 18           mgr                    integer,
 19           region                 number,
 20           division               number,
 21           total_sales            number
 22  );

Table created.

SQL> -- emp Table Inserts:
SQL> insert into emp(emp_no, lastname, firstname, midinit, street, city, state, zip,shortZipCode, area_code, phone, birthdate, title)values
  2                      (1,'Z','Joy','R','1 Ave','New York','NY','12122','2333','212','200-1111','12-nov-1976','President');

1 row created.

SQL> insert into emp(emp_no, lastname, firstname, midinit, street, city, state, zip,shortZipCode, area_code, phone, salary, birthdate, startDate,title, dept_no, mgr, region, division, total_sales)valu
es
  2                      (2,'X','Lucy','J','1 Street','New York','NY','43552','6633','212','234-4444',7.75,'21-mar-1976','1-feb-1994','Sales Manager',2,1,100,10,40000);

1 row created.

SQL> insert into emp(emp_no, lastname, firstname, midinit, street, city, state, zip,shortZipCode, area_code, phone, salary, birthdate, startDate,title, dept_no, mgr, region, division, total_sales)valu
es
  2                      (3,'Y','Jordan','E','1 Drive','New York','NY','76822','8763','212','222-2222',7.75,'14-feb-1963','15-mar-1995','Sales Clerk',2,2,100,10,10000);

1 row created.

SQL>
SQL> select
  2  case when salary between 6 and 10 then 'Salary 06-10'
  3       when salary between 11 and 15 then 'Salary 11-15'
  4       when salary between 16 and 20 then 'Salary 16-20'
  5       when salary between 21 and 25 then 'Salary 21-25'
  6       else 'Salary OOR'
  7       end
  8       AS bucket,
  9  count(*) num_emps
 10  from emp
 11  group by
 12  case when salary between 6 and 10 then 'Salary 06-10'
 13       when salary between 11 and 15 then 'Salary 11-15'
 14       when salary between 16 and 20 then 'Salary 16-20'
 15       when salary between 21 and 25 then 'Salary 21-25'
 16       else 'Salary OOR'
 17       end
 18  /

BUCKET         NUM_EMPS
------------ ----------
Salary 06-10          2
Salary OOR            1

2 rows selected.

SQL>
SQL> drop table emp;

Table dropped.

SQL>

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