?? SQL ??: INNER JOIN ? OUTER JOIN
INNER JOIN ??? OUTER JOIN? ???? OUTER JOIN? ??? ?????? ?? ?? ????? INNER JOIN? ?? OUTER JOIN?? ?? ??? ????
??? ?????. ?? INNER JOIN? OUTER JOIN ?? ON? ?? NULL? ? ? ?? ?? ??? ?? ???? OUTER JOIN? ??????. ??? ??? ????? ????? ? ??? ???? ????. INNER JOIN? ??? OUTER JOIN?? ???? ???.
??? ?????.
? 1(???? ???? ??):
SELECT * FROM person LEFT JOIN address ON person.address_id = address.id INNER JOIN email ON person.email_id = email.id
??? ?? ??? ???? ??? ???? ????.
? 2(?? ???):
SELECT * FROM person LEFT JOIN address ON person.address_id = address.id INNER JOIN city ON address.city_id = city.id
? ?? ON ??? NULL? ?? address.city_id? ?????. ?? LEFT OUTER JOIN? ???? person? ?? ???? city ?? address ???? ??????. ?? ????? INNER JOIN? LEFT OUTER JOIN?? ????.
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??? ?? ??? ???? ????? INNER JOIN? OUTER JOIN ?? ???? ?? ????. ?? ?? ???? ???? ??? ?? ??? ??? ??????. ??? RIGHT OUTER JOIN? ? ???? ??? ??? ????? ? ?? ???? ?? ???? ?? LEFT OUTER JOIN? ???? ?? ??? ? ????.
? ??? OUTER JOIN ??? INNER JOIN? OUTER JOIN? ??? ???????? ?? ?????. ??? ??? PHP ??? ????? ?? ?? ??? ?????!
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