{"id":152947,"date":"2024-11-02T03:21:20","date_gmt":"2024-11-01T19:21:20","guid":{"rendered":"https:\/\/server.hk\/cnblog\/152947\/"},"modified":"2024-11-02T03:21:21","modified_gmt":"2024-11-01T19:21:21","slug":"%e9%99%a4%e4%ba%86-inner-join-%e5%a4%96%ef%bc%8cmysql-%e4%b8%ad%e9%82%84%e6%9c%89%e5%93%aa%e4%ba%9b%e5%85%b6%e4%bb%96%e9%a1%9e%e5%9e%8b%e7%9a%84-join%ef%bc%9f","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/152947\/","title":{"rendered":"\u9664\u4e86 INNER JOIN \u5916\uff0cMySQL \u4e2d\u9084\u6709\u54ea\u4e9b\u5176\u4ed6\u985e\u578b\u7684 JOIN\uff1f"},"content":{"rendered":"

\u9664\u4e86 INNER JOIN \u5916\uff0cMySQL \u4e2d\u9084\u6709\u54ea\u4e9b\u5176\u4ed6\u985e\u578b\u7684 JOIN\uff1f<\/h1>\n

\u5728\u95dc\u806f\u578b\u8cc7\u6599\u5eab\u4e2d\uff0cJOIN \u662f\u4e00\u500b\u975e\u5e38\u91cd\u8981\u7684\u6982\u5ff5\uff0c\u5b83\u5141\u8a31\u6211\u5011\u5f9e\u591a\u500b\u8868\u4e2d\u6aa2\u7d22\u6578\u64da\u3002MySQL \u63d0\u4f9b\u4e86\u591a\u7a2e JOIN \u985e\u578b\uff0c\u9664\u4e86\u6700\u5e38\u7528\u7684 INNER JOIN\uff0c\u9084\u6709\u5176\u4ed6\u5e7e\u7a2e JOIN \u985e\u578b\uff0c\u6bcf\u7a2e\u90fd\u6709\u5176\u7279\u5b9a\u7684\u7528\u9014\u548c\u7279\u9ede\u3002\u672c\u6587\u5c07\u6df1\u5165\u63a2\u8a0e MySQL \u4e2d\u7684\u5404\u7a2e JOIN \u985e\u578b\uff0c\u5e6b\u52a9\u8b80\u8005\u66f4\u597d\u5730\u7406\u89e3\u5982\u4f55\u5728\u67e5\u8a62\u4e2d\u4f7f\u7528\u5b83\u5011\u3002<\/p>\n

1. LEFT JOIN\uff08\u6216 LEFT OUTER JOIN\uff09<\/h2>\n

LEFT JOIN \u662f\u4e00\u7a2e\u5916\u90e8\u9023\u63a5\uff0c\u5b83\u8fd4\u56de\u5de6\u5074\u8868\u4e2d\u7684\u6240\u6709\u884c\uff0c\u5373\u4f7f\u5728\u53f3\u5074\u8868\u4e2d\u6c92\u6709\u5339\u914d\u7684\u884c\u3002\u9019\u610f\u5473\u8457\u5982\u679c\u5de6\u5074\u8868\u4e2d\u7684\u67d0\u884c\u5728\u53f3\u5074\u8868\u4e2d\u627e\u4e0d\u5230\u5c0d\u61c9\u7684\u884c\uff0c\u5247\u7d50\u679c\u4e2d\u4ecd\u6703\u986f\u793a\u8a72\u884c\uff0c\u4e26\u4e14\u53f3\u5074\u8868\u7684\u6240\u6709\u5217\u5c07\u986f\u793a\u70ba NULL\u3002<\/p>\n

SELECT a.*, b.*\nFROM table_a a\nLEFT JOIN table_b b ON a.id = b.a_id;<\/code><\/pre>\n
\u5728\u9019\u500b\u4f8b\u5b50\u4e2d\uff0c\u7121\u8ad6 table_b \u4e2d\u662f\u5426\u6709\u8207 table_a \u4e2d\u7684\u884c\u5339\u914d\u7684\u884c\uff0ctable_a \u4e2d\u7684\u6240\u6709\u884c\u90fd\u6703\u88ab\u8fd4\u56de\u3002<\/p>\n
2. RIGHT JOIN\uff08\u6216 RIGHT OUTER JOIN\uff09<\/h2>\n
RIGHT JOIN \u8207 LEFT JOIN \u76f8\u5c0d\uff0c\u5b83\u8fd4\u56de\u53f3\u5074\u8868\u4e2d\u7684\u6240\u6709\u884c\uff0c\u5373\u4f7f\u5728\u5de6\u5074\u8868\u4e2d\u6c92\u6709\u5339\u914d\u7684\u884c\u3002\u9019\u610f\u5473\u8457\u5982\u679c\u53f3\u5074\u8868\u4e2d\u7684\u67d0\u884c\u5728\u5de6\u5074\u8868\u4e2d\u627e\u4e0d\u5230\u5c0d\u61c9\u7684\u884c\uff0c\u5247\u7d50\u679c\u4e2d\u4ecd\u6703\u986f\u793a\u8a72\u884c\uff0c\u4e26\u4e14\u5de6\u5074\u8868\u7684\u6240\u6709\u5217\u5c07\u986f\u793a\u70ba NULL\u3002<\/p>\n
SELECT a.*, b.*\nFROM table_a a\nRIGHT JOIN table_b b ON a.id = b.a_id;<\/code><\/pre>\n
\u9019\u500b\u67e5\u8a62\u5c07\u8fd4\u56de table_b \u4e2d\u7684\u6240\u6709\u884c\uff0c\u4e26\u4e14\u5982\u679c table_a \u4e2d\u6c92\u6709\u5339\u914d\u7684\u884c\uff0c\u5247\u76f8\u61c9\u7684\u5217\u5c07\u986f\u793a\u70ba NULL\u3002<\/p>\n
3. FULL JOIN\uff08\u6216 FULL OUTER JOIN\uff09<\/h2>\n
FULL JOIN \u662f\u4e00\u7a2e\u7d50\u5408\u4e86 LEFT JOIN \u548c RIGHT JOIN \u7684\u5916\u90e8\u9023\u63a5\u3002\u5b83\u8fd4\u56de\u5169\u500b\u8868\u4e2d\u7684\u6240\u6709\u884c\uff0c\u7121\u8ad6\u662f\u5426\u6709\u5339\u914d\u7684\u884c\u3002\u5982\u679c\u67d0\u4e00\u5074\u7684\u8868\u4e2d\u6c92\u6709\u5339\u914d\u7684\u884c\uff0c\u5247\u8a72\u5074\u7684\u5217\u5c07\u986f\u793a\u70ba NULL\u3002<\/p>\n
\u9700\u8981\u6ce8\u610f\u7684\u662f\uff0cMySQL \u672c\u8eab\u4e0d\u76f4\u63a5\u652f\u6301 FULL JOIN\uff0c\u4f46\u53ef\u4ee5\u901a\u904e\u7d50\u5408 LEFT JOIN \u548c RIGHT JOIN \u4f86\u5be6\u73fe\uff1a<\/p>\n
SELECT a.*, b.*\nFROM table_a a\nLEFT JOIN table_b b ON a.id = b.a_id\nUNION\nSELECT a.*, b.*\nFROM table_a a\nRIGHT JOIN table_b b ON a.id = b.a_id;<\/code><\/pre>\n
4. CROSS JOIN<\/h2>\n
CROSS JOIN \u6703\u8fd4\u56de\u5169\u500b\u8868\u7684\u7b1b\u5361\u723e\u7a4d\uff0c\u5373\u6bcf\u4e00\u884c\u90fd\u6703\u8207\u53e6\u4e00\u500b\u8868\u4e2d\u7684\u6bcf\u4e00\u884c\u9032\u884c\u7d44\u5408\u3002\u9019\u901a\u5e38\u6703\u7522\u751f\u5927\u91cf\u7684\u7d50\u679c\u96c6\uff0c\u56e0\u6b64\u5728\u4f7f\u7528\u6642\u9700\u8981\u8b39\u614e\u3002<\/p>\n
SELECT a.*, b.*\nFROM table_a a\nCROSS JOIN table_b b;<\/code><\/pre>\n
\u9019\u500b\u67e5\u8a62\u5c07\u8fd4\u56de table_a \u548c table_b \u4e2d\u6240\u6709\u53ef\u80fd\u7684\u884c\u7d44\u5408\u3002<\/p>\n
5. SELF JOIN<\/h2>\n
SELF JOIN \u662f\u4e00\u7a2e\u7279\u6b8a\u7684 JOIN\uff0c\u7576\u4e00\u500b\u8868\u9700\u8981\u8207\u81ea\u8eab\u9032\u884c\u9023\u63a5\u6642\u4f7f\u7528\u3002\u9019\u901a\u5e38\u7528\u65bc\u67e5\u8a62\u5177\u6709\u5c64\u6b21\u7d50\u69cb\u7684\u6578\u64da\uff0c\u4f8b\u5982\u54e1\u5de5\u548c\u5176\u4e0a\u7d1a\u4e4b\u9593\u7684\u95dc\u4fc2\u3002<\/p>\n
SELECT a.name AS Employee, b.name AS Manager\nFROM employees a\nJOIN employees b ON a.manager_id = b.id;<\/code><\/pre>\n
\u5728\u9019\u500b\u4f8b\u5b50\u4e2d\uff0c\u6211\u5011\u67e5\u8a62\u4e86\u6bcf\u4f4d\u54e1\u5de5\u53ca\u5176\u7d93\u7406\u7684\u540d\u7a31\u3002<\/p>\n
\u7e3d\u7d50<\/h2>\n
\u5728 MySQL \u4e2d\uff0c\u9664\u4e86 INNER JOIN \u5916\uff0c\u9084\u6709\u591a\u7a2e JOIN \u985e\u578b\u53ef\u4f9b\u4f7f\u7528\uff0c\u5305\u62ec LEFT JOIN\u3001RIGHT JOIN\u3001FULL JOIN\u3001CROSS JOIN \u548c SELF JOIN\u3002\u6bcf\u7a2e JOIN \u985e\u578b\u90fd\u6709\u5176\u7279\u5b9a\u7684\u7528\u9014\uff0c\u6839\u64da\u9700\u6c42\u9078\u64c7\u5408\u9069\u7684 JOIN \u985e\u578b\u53ef\u4ee5\u6709\u6548\u5730\u63d0\u9ad8\u67e5\u8a62\u6548\u7387\u548c\u6578\u64da\u7684\u53ef\u8b80\u6027\u3002\u4e86\u89e3\u9019\u4e9b JOIN \u7684\u7279\u6027\u548c\u7528\u6cd5\uff0c\u5c0d\u65bc\u6578\u64da\u5eab\u7ba1\u7406\u548c\u67e5\u8a62\u512a\u5316\u81f3\u95dc\u91cd\u8981\u3002<\/p>\n
\u5982\u679c\u60a8\u6b63\u5728\u5c0b\u627e\u9ad8\u6548\u7684 VPS<\/a> \u89e3\u6c7a\u65b9\u6848\uff0cServer.HK \u63d0\u4f9b\u591a\u7a2e\u9078\u64c7\uff0c\u6eff\u8db3\u60a8\u7684\u9700\u6c42\u3002\u7121\u8ad6\u662f \u9999\u6e2f\u4f3a\u670d\u5668<\/a> \u9084\u662f \u4e91\u4f3a\u670d\u5668<\/a>\uff0c\u6211\u5011\u90fd\u80fd\u70ba\u60a8\u63d0\u4f9b\u7a69\u5b9a\u53ef\u9760\u7684\u670d\u52d9\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
\u63a2\u7d22 MySQL \u4e2d\u9664\u4e86 INNER JOIN \u5916\u7684\u5176\u4ed6 JOIN \u985e\u578b\uff0c\u5305\u62ec LEFT JOIN\u3001RIGHT JOIN \u548c FULL OUTER JOIN\uff0c\u4e86\u89e3\u5b83\u5011\u7684\u7528\u6cd5\u548c\u5dee\u7570\u3002<\/p>\n","protected":false},"author":0,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[101],"tags":[],"class_list":["post-152947","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/152947","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/types\/post"}],"replies":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/comments?post=152947"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/152947\/revisions"}],"predecessor-version":[{"id":152948,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/152947\/revisions\/152948"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=152947"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=152947"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=152947"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}