{"id":965,"date":"2025-05-20T08:52:19","date_gmt":"2025-05-20T08:52:19","guid":{"rendered":"https:\/\/office.chm.kr\/?page_id=965"},"modified":"2025-05-20T08:52:19","modified_gmt":"2025-05-20T08:52:19","slug":"my-sql-join","status":"publish","type":"page","link":"https:\/\/office.chm.kr\/?page_id=965","title":{"rendered":"My SQL JOIN"},"content":{"rendered":"\n

\uc6f9\uc5d0\uc11c \uac8c\uc2dc\ud310\uc744 \ub9cc\ub4e4\uc5b4\ubcf4\uac8c \ub418\uba74\uc11c DataBase<\/code>\ub97c \uc811\ud558\uac8c \ub418\uc5c8\ub2e4. \uac01 \uc8fc\uc81c\uc5d0 \ub530\ub77c \ud14c\uc774\ube14\uc744 \ub098\ub204\uc5b4 \uc791\uc131\ud55c \ud6c4, \uc815\ubcf4\ub97c \uac00\uc838\uc624\ub294 \uacbd\uc6b0 \ud14c\uc774\ube14\uc744 \ud569\uce58\ub294 \uacbd\uc6b0\uac00 \uc788\uc5c8\ub2e4. \uc774\ub54c JOIN<\/code>\uc744 \uc0ac\uc6a9\ud558\uac8c \ub418\ub294\ub370, \uadf8 \uc911 \ub9ce\uc774 \uc0ac\uc6a9\ud558\ub294 \uac83\uc774 LEFT JOIN<\/code>\uacfc INNER JOIN<\/code>\uc774\uc5c8\ub2e4. \uc774 \ub458\uc758 \ucc28\uc774\uc5d0 \ub300\ud574 \uc54c\uc544\ubcf4\uc790.<\/p>\n\n\n\n

\n\n\n\n

\uc544\ub798\ub294 \uc608\uc81c\ub85c \uc0ac\uc6a9\ud560 \ud14c\uc774\ube14\uc774\ub2e4. DBMS<\/code>\ub294 MariaDB<\/code>\ub97c \uc0ac\uc6a9\ud588\ub2e4.<\/p>\n\n\n\n

SELECT * FROM topic;\n+-----+------------+------------------+-----------+\n| tid | title      | description      | author_id |\n+-----+------------+------------------+-----------+\n|   1 | HTML       | HTML is ...      | 1         |\n|   2 | CSS        | CSS is ...       | 2         |\n|   3 | JavaScript | JavaScript is .. | 1         |\n|   4 | Database   | Database is ...  | NULL      |\n+-----+------------+------------------+-----------+\n\nSELECT * FROM author;\n+-----+----------+--------+------------+\n| aid | name     | city   | profile_id |\n+-----+----------+--------+------------+\n|   1 | egoing   | seoul  |          1 |\n|   2 | leezche  | jeju   |          2 |\n|   3 | blackdew | namhae |          3 |\n+-----+----------+--------+------------+<\/code><\/pre>\n\n\n\n
\uad50\uc9d1\ud569, \ud569\uc9d1\ud569\uc5d0 \ub300\ud55c \uc124\uba85\uc740 \uc544\ub798 \uc774\ubbf8\uc9c0\ub97c \ucc38\uace0\ud574\ub77c.<\/p>\n\n\n\n
\"INNER<\/figure>\n\n\n\n
\n\n\n\n
OUTER JOIN - \ud569\uc9d1\ud569<\/code><\/h2>\n\n\n\n
LEFT JOIN<\/code>\uc740 OUTER JOIN<\/code>\uc758 \uc77c\uc885\uc774\ub2e4. \ub530\ub77c\uc11c LEFT OUTER JOIN<\/code>\uc774\ub77c\uace0 \ubcfc \uc218 \uc788\ub2e4.
OUTER JOIN<\/code>\uc740 \ud569\uc9d1\ud569<\/strong>\uc744 \uc758\ubbf8\ud55c\ub2e4.<\/p>\n\n\n\n
\uc5ec\uae30\uc11c LEFT JOIN<\/code>\uc740 \uc67c\ucabd\uc758 \ubaa8\ub4e0 \ud589\uc744 \uc870\ud68c<\/strong>\ud55c\ub2e4. \ub530\ub77c\uc11c topic<\/code>\ud14c\uc774\ube14\uc758 author_id<\/code> \ud544\ub4dc\uc758 \uac12\uc774 NULL<\/code>\uc774\uba74, author<\/code> \ud14c\uc774\ube14\uc740 \ud574\ub2f9 \ud589\uc774 \uc874\uc7ac\ud558\uc9c0 \uc54a\uc73c\ubbc0\ub85c \ud574\ub2f9 \ud589\uc758 \ud544\ub4dc \uac12\ub4e4\uc740 NULL<\/code>\ub85c \ucc44\uc6cc\uc9c4\ub2e4.<\/p>\n\n\n\n
SELECT * FROM topic LEFT JOIN author ON topic.author_id = author.aid;\n+-----+------------+------------------+-----------+------+---------+-------+------------+\n| tid | title      | description      | author_id | aid  | name    | city  | profile_id |\n+-----+------------+------------------+-----------+------+---------+-------+------------+\n|   1 | HTML       | HTML is ...      | 1         |    1 | egoing  | seoul |          1 |\n|   2 | CSS        | CSS is ...       | 2         |    2 | leezche | jeju  |          2 |\n|   3 | JavaScript | JavaScript is .. | 1         |    1 | egoing  | seoul |          1 |\n|   4 | Database   | Database is ...  | NULL      | NULL | NULL    | NULL  |       NULL |\n+-----+------------+------------------+-----------+------+---------+-------+------------+<\/code><\/pre>\n\n\n\n
\n\n\n\n
INNER JOIN - \uad50\uc9d1\ud569<\/code><\/h2>\n\n\n\n
\ub9d0 \uadf8\ub300\ub85c \uad50\uc9d1\ud569<\/strong>\uc744 \ub098\ud0c0\ub0b8\ub2e4. \ub530\ub77c\uc11c \uacb9\uce58\uc9c0 \uc54a\ub294 \ud589\uc774 \uc874\uc7ac\ud560 \uacbd\uc6b0, \uadf8 \ud589\uc740 \uacb0\uacfc\uc5d0\uc11c \uc81c\uc678<\/strong>\ub41c\ub2e4.
\uacb0\uacfc\ub97c \ubcf4\uba74 author_id<\/code>\uac00 NULL<\/code>\uc778 \ud589\uc774 \uacb0\uacfc\uc5d0\uc11c \uc81c\uc678\ub41c \uac83\uc744 \uc54c \uc218 \uc788\ub2e4.<\/p>\n\n\n\n
SELECT * FROM topic INNER JOIN author ON topic.author_id = author.aid;\n+-----+------------+------------------+-----------+-----+---------+-------+------------+\n| tid | title      | description      | author_id | aid | name    | city  | profile_id |\n+-----+------------+------------------+-----------+-----+---------+-------+------------+\n|   1 | HTML       | HTML is ...      | 1         |   1 | egoing  | seoul |          1 |\n|   2 | CSS        | CSS is ...       | 2         |   2 | leezche | jeju  |          2 |\n|   3 | JavaScript | JavaScript is .. | 1         |   1 | egoing  | seoul |          1 |\n+-----+------------+------------------+-----------+-----+---------+-------+------------+<\/code><\/pre>\n\n\n\n
\n\n\n\n
\uc131\ub2a5 \ucc28\uc774<\/h2>\n\n\n\n
\ub450 \ud14c\uc774\ube14\uc5d0\uc11c JOIN<\/code>\uc744 \uc704\ud55c \uae30\uc900 \uc5f4\uc774 \uc11c\ub85c \uac12\uc744 \uac00\uc9c0\uace0 \uc788\ub294 \uacbd\uc6b0<\/strong> \uc870\ud68c\uc5d0\uc11c \ub204\ub77d\ub418\ub294 \ud589\uc740 \uc874\uc7ac\ud558\uc9c0 \uc54a\ub294\ub2e4.<\/strong><\/p>\n\n\n\n
\uadf8\ub807\ub2e4\uba74 LEFT JOIN<\/code>\uacfc INNER JOIN<\/code>\uc740 \uac19\uc740 \uc870\ud68c \uacb0\uacfc\ub97c \ubcf4\uc778\ub2e4. \uc774\ub54c, INNER JOIN<\/code>\uc774 \uc0c1\ub300\uc801\uc73c\ub85c \uc131\ub2a5\uc774 \uc88b\ub2e4<\/strong>\uace0 \ud55c\ub2e4.<\/p>\n\n\n\n
\uad50\uc9d1\ud569\ub9cc \uace0\ub824\ud558\ub2e4\ubcf4\ub2c8 \ube60\ub97c \uac83 \uac19\uae34 \ud558\ub2e4.<\/p>\n\n\n\n
\n\n\n\n
\uc815\ub9ac<\/h2>\n\n\n\n
\n
LEFT JOIN<\/code>\uc740 \ud569\uc9d1\ud569<\/strong>, INNER JOIN<\/code>\uc740 \uad50\uc9d1\ud569<\/strong>\uc774\ub2e4.
\uacb0\uacfc\uac00 \uac19\ub2e4\uba74 LEFT JOIN<\/code> \ub300\uc2e0 INNER JOIN<\/code>\uc744 \uc0ac\uc6a9\ud558\uc790.<\/p>\n<\/blockquote>\n","protected":false},"excerpt":{"rendered":"
\uc6f9\uc5d0\uc11c \uac8c\uc2dc\ud310\uc744 \ub9cc\ub4e4\uc5b4\ubcf4\uac8c \ub418\uba74\uc11c DataBase\ub97c \uc811\ud558\uac8c \ub418\uc5c8\ub2e4. \uac01 \uc8fc\uc81c\uc5d0 \ub530\ub77c \ud14c\uc774\ube14\uc744 \ub098\ub204\uc5b4 \uc791\uc131\ud55c \ud6c4, \uc815\ubcf4\ub97c \uac00\uc838\uc624\ub294 \uacbd\uc6b0 \ud14c\uc774\ube14\uc744 \ud569\uce58\ub294 \uacbd\uc6b0\uac00 \uc788\uc5c8\ub2e4. \uc774\ub54c JOIN\uc744 \uc0ac\uc6a9\ud558\uac8c \ub418\ub294\ub370, \uadf8 \uc911 \ub9ce\uc774 \uc0ac\uc6a9\ud558\ub294 \uac83\uc774 LEFT JOIN\uacfc INNER JOIN\uc774\uc5c8\ub2e4. \uc774 \ub458\uc758 \ucc28\uc774\uc5d0 \ub300\ud574 \uc54c\uc544\ubcf4\uc790. \uc544\ub798\ub294 \uc608\uc81c\ub85c \uc0ac\uc6a9\ud560 \ud14c\uc774\ube14\uc774\ub2e4. DBMS\ub294 MariaDB\ub97c \uc0ac\uc6a9\ud588\ub2e4. \uad50\uc9d1\ud569, \ud569\uc9d1\ud569\uc5d0 \ub300\ud55c \uc124\uba85\uc740 \uc544\ub798 \uc774\ubbf8\uc9c0\ub97c \ucc38\uace0\ud574\ub77c. OUTER JOIN – \ud569\uc9d1\ud569 LEFT JOIN\uc740 OUTER JOIN\uc758 \uc77c\uc885\uc774\ub2e4.… \ub354 \ubcf4\uae30 »My SQL JOIN<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"neve_meta_sidebar":"","neve_meta_container":"","neve_meta_enable_content_width":"","neve_meta_content_width":0,"neve_meta_title_alignment":"","neve_meta_author_avatar":"","neve_post_elements_order":"","neve_meta_disable_header":"","neve_meta_disable_footer":"","neve_meta_disable_title":"","_themeisle_gutenberg_block_has_review":false,"footnotes":""},"class_list":["post-965","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/office.chm.kr\/index.php?rest_route=\/wp\/v2\/pages\/965","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/office.chm.kr\/index.php?rest_route=\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/office.chm.kr\/index.php?rest_route=\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/office.chm.kr\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/office.chm.kr\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=965"}],"version-history":[{"count":1,"href":"https:\/\/office.chm.kr\/index.php?rest_route=\/wp\/v2\/pages\/965\/revisions"}],"predecessor-version":[{"id":966,"href":"https:\/\/office.chm.kr\/index.php?rest_route=\/wp\/v2\/pages\/965\/revisions\/966"}],"wp:attachment":[{"href":"https:\/\/office.chm.kr\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=965"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}