LEFT OUTER JOIN of RIGHT OUTER JOIN vinden met ORACLE JOIN (+)

Verduidelijk hoe u de rechter en linker outer join correct kunt vinden met een voorbeeld

Ik zal proberen het verschil tussen Oracle outer join-syntaxis te laten zien en de ANSI/ISO-syntaxis .

LINKER BUITENSTE JOIN -

SELECT e.last_name,
  d.department_name
FROM employees e,
  departments d
WHERE e.department_id = d.department_id(+);

SELECT e.last_name,
  d.department_name
FROM employees e
LEFT OUTER JOIN departments d
ON (e.department_id = d.department_id);

RIGHT OUTER JOIN -

SELECT e.last_name,
  d.department_name
FROM employees e,
  departments d
WHERE e.department_id(+) = d.department_id;

SELECT e.last_name,
  d.department_name
FROM employees e
RIGHT OUTER JOIN departments d
ON (e.department_id = d.department_id);

VOLLEDIGE OUTER JOIN -

Vóór de native ondersteuning van hash full outerjoin in 11gR1, zou Oracle de FULL OUTER JOIN op de volgende manier intern converteren -

SELECT e.last_name,
  d.department_name
FROM employees e,
  departments d
WHERE e.department_id = d.department_id(+)
UNION ALL
SELECT NULL,
  d.department_name
FROM departments d
WHERE NOT EXISTS
  (SELECT 1 FROM employees e WHERE e.department_id = d.department_id
  );

SELECT e.last_name,
  d.department_name
FROM employees e
FULL OUTER JOIN departments d
ON (e.department_id = d.department_id);

Kijk hier eens naar.