SQL>
SQL>
SQL> CREATE TABLE employees
2 ( employee_id number(10) not null,
3 last_name varchar2(50) not null,
4 email varchar2(30),
5 hire_date date,
6 job_id varchar2(30),
7 department_id number(10),
8 salary number(6),
9 manager_id number(6)
10 );
Table created.
SQL>
SQL>
SQL> insert into employees( employee_id, last_name, email, hire_date, job_id, salary,department_id ,manager_id)
2 values ( 1001, 'Lawson', 'lawson@g.com', '01-JAN-2002','MGR', 30000,1 ,1004);
1 row created.
SQL>
SQL> insert into employees( employee_id, last_name, email, hire_date, job_id, salary, department_id ,manager_id)
2 values ( 1002, 'Wells', 'wells@g.com', '01-JAN-2002', 'DBA', 20000,2, 1005 );
1 row created.
SQL>
SQL> insert into employees( employee_id, last_name, email, hire_date, job_id, salary, department_id ,manager_id)
2 values( 1003, 'Bliss', 'bliss@g.com', '01-JAN-2002', 'PROG', 24000,3 ,1004);
1 row created.
SQL>
SQL> insert into employees( employee_id, last_name, email, hire_date, job_id, salary, department_id, manager_id)
2 values( 1004, 'Kyte', 'tkyte@a.com', SYSDATE-3650, 'MGR',25000 ,4, 1005);
1 row created.
SQL>
SQL> insert into employees( employee_id, last_name, email, hire_date, job_id, salary, department_id, manager_id)
2 values( 1005, 'Viper', 'sdillon@a .com', SYSDATE, 'PROG', 20000, 1, 1006);
1 row created.
SQL>
SQL> insert into employees( employee_id, last_name, email, hire_date, job_id, salary, department_id,manager_id)
2 values( 1006, 'Beck', 'clbeck@g.com', SYSDATE, 'PROG', 20000, 2, null);
1 row created.
SQL>
SQL> insert into employees( employee_id, last_name, email, hire_date, job_id, salary, department_id, manager_id)
2 values( 1007, 'Java', 'java01@g.com', SYSDATE, 'PROG', 20000, 3, 1006);
1 row created.
SQL>
SQL> insert into employees( employee_id, last_name, email, hire_date, job_id, salary, department_id, manager_id)
2 values( 1008, 'Oracle', 'wvelasq@g.com', SYSDATE, 'DBA', 20000, 4, 1006);
1 row created.
SQL>
SQL>
SQL> set autotrace on
SQL> set timing on
SQL>
SQL> select employee_id,
2 count(*) total_orders
3 from employees
4 group by employee_id
5 /
EMPLOYEE_ID TOTAL_ORDERS
----------- ------------
1003 1
1006 1
1001 1
1002 1
1007 1
1004 1
1005 1
1008 1
8 rows selected.
Elapsed: 00:00:00.11
Execution Plan
----------------------------------------------------------
Plan hash value: 1192169904
--------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
--------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 8 | 104 | 3 (34)| 00:00:01 |
| 1 | HASH GROUP BY | | 8 | 104 | 3 (34)| 00:00:01 |
| 2 | TABLE ACCESS FULL| EMPLOYEES | 8 | 104 | 2 (0)| 00:00:01 |
--------------------------------------------------------------------------------
Note
-----
- dynamic sampling used for this statement
Statistics
----------------------------------------------------------
28 recursive calls
0 db block gets
9 consistent gets
0 physical reads
0 redo size
574 bytes sent via SQL*Net to client
380 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
8 rows processed
SQL> set autotrace off
SQL> set timing off
SQL>
SQL> drop table employees;
Table dropped.
SQL>