Joins with USING Keyword

SQL/92 simplifies the join condition with the USING clause with the following limitations:

The query must use an equijoin. The columns in the equijoin must have the same name.


CREATE TABLE departments
(department_id             number(10)            not null,
 department_name           varchar2(50)      not null,
 CONSTRAINT departments_pk PRIMARY KEY (department_id)
);

insert into departments ( department_id, department_name )values(1,'Data Group' );
insert into departments ( department_id, department_name )values(2,'Purchasing' );
insert into departments ( department_id, department_name )values(3,'Call Center' );
insert into departments ( department_id, department_name )values(4,'Communication' );

CREATE TABLE employees
( employee_id          number(10)      not null,
  last_name            varchar2(50)      not null,
  job_id               varchar2(30),
  department_id        number(10),
  salary               number(6),
  manager_id           number(6),
  CONSTRAINT           employees_pk PRIMARY KEY (employee_id),
  CONSTRAINT           fk_departments FOREIGN KEY (department_id) 
                       REFERENCES departments(department_id)
);
insert into employees( employee_id, last_name, job_id, salary,department_id ,manager_id)
values(                1001,        'Lawson',  'MGR',  30000, 1,             1004);
insert into employees( employee_id, last_name, job_id, salary, department_id ,manager_id)
values(                1002,        'Wells',   'DBA',  20000, 2,             1005 );
insert into employees( employee_id, last_name, job_id, salary, department_id ,manager_id)
values(                1003,        'Bliss',   'PROG', 24000, 3,             1004);
insert into employees( employee_id, last_name, job_id, salary, department_id, manager_id)
values(                1004,        'Kyte',    'MGR',  25000 ,4,             1005);
insert into employees( employee_id, last_name, job_id, salary, department_id, manager_id)
values(                1005,        'Viper',   'PROG', 20000, 1,             1006);
insert into employees( employee_id, last_name, job_id, salary, department_id,manager_id)
values(                1006,        'Beck',    'PROG', 20000, 2,             null);
insert into employees( employee_id, last_name, job_id, salary, department_id, manager_id)
values(                1007,        'Java',    'PROG', 20000, 3,             1006);
insert into employees( employee_id, last_name, job_id, salary, department_id, manager_id)
values(                1008,        'Oracle',  'DBA',  20000, 4,             1006);


SQL> select employee_id, last_name, department_name
  2  from employees INNER JOIN departments
  3  Using (department_id)
  4  ;

EMPLOYEE_ID LAST_NAME                 DEPARTMENT_NAME
----------- --------------------------------------------------
       1001 Lawson                    Data Group
       1002 Wells                     Purchasing
       1003 Bliss                     Call Center
       1004 Kyte                      Communication
       1005 Viper                     Data Group
       1006 Beck                      Purchasing
       1007 Java                      Call Center
       1008 Oracle                    Communication


8 rows selected.

SQL>

With Using keyword style, table alias is not allowed in the select statement for the joining column


SQL> select employee_id, last_name, department_name,departments.department_id
  2  from employees INNER JOIN departments
  3  Using (department_id)
  4  ;
select employee_id, last_name, department_name,departments.department_id
                                               *
ERROR at line 1:
ORA-25154: column part of USING clause cannot have qualifier


SQL>
SQL> select e.employee_id, e.last_name, d.department_name,d.department_id
  2  from employees e INNER JOIN departments d
  3  Using (department_id)
  4  ;
select e.employee_id, e.last_name, d.department_name,d.department_id
                                                     *
ERROR at line 1:
ORA-25154: column part of USING clause cannot have qualifier


SQL>
SQL>
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Join:
  1. Table Join
  2. Using Table name to reference duplicate names
  3. Table Alias
  4. Cartesian Products
  5. Join more than two tables
  6. Join Conditions and Join Types
  7. Outer Joins
  8. Left and Right Outer Joins
  9. Outer join Error
  10. Self Join
  11. Outer Self Join
  12. Inner Joins Using SQL/92
  13. Joins with USING Keyword
  14. Inner Joins with More than Two Tables Using SQL/92
  15. Inner Joins on Multiple Columns Using SQL/92
  16. Outer Joins in SQL/92 Syntax
  17. Self Joins Using SQL/92
  18. Cross Joins Using SQL/92
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