self join for employees and their managers : Self Joins « Table Joins « Oracle PL / SQL






self join for employees and their managers

 
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> select * from employees;

EMPLOYEE_ID LAST_NAME                                          EMAIL                          HIRE_DATE JOB_ID                         DEPARTMENT_ID     SALARY MANAGER_ID
----------- -------------------------------------------------- ------------------------------ --------- ------------------------------ ------------- ---------- ----------
       1001 Lawson                                             lawson@g.com                   01-JAN-02 MGR                                        1      30000       1004
       1002 Wells                                              wells@g.com                    01-JAN-02 DBA                                        2      20000       1005
       1003 Bliss                                              bliss@g.com                    01-JAN-02 PROG                                       3      24000       1004
       1004 Kyte                                               tkyte@a.com                    13-JUN-98 MGR                                        4      25000       1005
       1005 Viper                                              sdillon@a .com                 10-JUN-08 PROG                                       1      20000       1006
       1006 Beck                                               clbeck@g.com                   10-JUN-08 PROG                                       2      20000
       1007 Java                                               java01@g.com                   10-JUN-08 PROG                                       3      20000       1006

EMPLOYEE_ID LAST_NAME                                          EMAIL                          HIRE_DATE JOB_ID                         DEPARTMENT_ID     SALARY MANAGER_ID
----------- -------------------------------------------------- ------------------------------ --------- ------------------------------ ------------- ---------- ----------
       1008 Oracle                                             wvelasq@g.com                  10-JUN-08 DBA                                        4      20000       1006

8 rows selected.

SQL>
SQL> select employee_id, last_name, job_id, manager_id
  2        from employees
  3       order by employee_id
  4  /

EMPLOYEE_ID LAST_NAME                                          JOB_ID                         MANAGER_ID
----------- -------------------------------------------------- ------------------------------ ----------
       1001 Lawson                                             MGR                                  1004
       1002 Wells                                              DBA                                  1005
       1003 Bliss                                              PROG                                 1004
       1004 Kyte                                               MGR                                  1005
       1005 Viper                                              PROG                                 1006
       1006 Beck                                               PROG
       1007 Java                                               PROG                                 1006

EMPLOYEE_ID LAST_NAME                                          JOB_ID                         MANAGER_ID
----------- -------------------------------------------------- ------------------------------ ----------
       1008 Oracle                                             DBA                                  1006

8 rows selected.

SQL> select e1.last_name "Employee",
  2             e2.last_name "Reports To"
  3        from employees e1 left outer join employees e2
  4          on e1.manager_id = e2.employee_id
  5       order by e1.employee_id
  6  /

Employee                                           Reports To
-------------------------------------------------- --------------------------------------------------
Lawson                                             Kyte
Wells                                              Viper
Bliss                                              Kyte
Kyte                                               Viper
Viper                                              Beck
Beck
Java                                               Beck

Employee                                           Reports To
-------------------------------------------------- --------------------------------------------------
Oracle                                             Beck

8 rows selected.

SQL>
SQL>
SQL> drop table employees;

Table dropped.

SQL>

 








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