{"id":200336,"date":"2025-05-06T12:46:23","date_gmt":"2025-05-06T04:46:23","guid":{"rendered":"https:\/\/server.hk\/cnblog\/200336\/"},"modified":"2025-05-06T12:46:23","modified_gmt":"2025-05-06T04:46:23","slug":"%e5%a6%82%e4%bd%95%e4%bd%bf%e7%94%a8%e8%81%94%e8%a1%a8%e6%9f%a5%e8%af%a2%e8%8e%b7%e5%8f%96%e6%89%80%e6%9c%89%e7%ad%96%e7%95%a5%e4%bf%a1%e6%81%af%ef%bc%8c%e5%8d%b3%e4%bd%bf%e5%ae%83%e4%bb%ac%e6%b2%a1","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/200336\/","title":{"rendered":"\u5982\u4f55\u4f7f\u7528\u8054\u8868\u67e5\u8be2\u83b7\u53d6\u6240\u6709\u7b56\u7565\u4fe1\u606f\uff0c\u5373\u4f7f\u5b83\u4eec\u6ca1\u6709\u4e0e\u7ec4\u5173\u8054\uff1f"},"content":{"rendered":"<p><b><\/b> <\/p>\n<h1>\u5982\u4f55\u4f7f\u7528\u8054\u8868\u67e5\u8be2\u83b7\u53d6\u6240\u6709\u7b56\u7565\u4fe1\u606f\uff0c\u5373\u4f7f\u5b83\u4eec\u6ca1\u6709\u4e0e\u7ec4\u5173\u8054\uff1f<\/h1>\n<p>\u4e00\u5206\u8015\u8018\uff0c\u4e00\u5206\u6536\u83b7\uff01\u65e2\u7136\u6253\u5f00\u4e86\u8fd9\u7bc7\u6587\u7ae0\uff0c\u5c31\u575a\u6301\u770b\u4e0b\u53bb\u5427\uff01\u6587\u4e2d\u5185\u5bb9\u5305\u542b\u7b49\u7b49\u77e5\u8bc6\u70b9&#8230;\u5e0c\u671b\u4f60\u80fd\u5728\u9605\u8bfb\u672c\u6587\u540e\uff0c\u80fd\u771f\u771f\u5b9e\u5b9e\u5b66\u5230\u77e5\u8bc6\u6216\u8005\u5e2e\u4f60\u89e3\u51b3\u5fc3\u4e2d\u7684\u7591\u60d1\uff0c\u4e5f\u6b22\u8fce\u5927\u4f6c\u6216\u8005\u65b0\u4eba\u670b\u53cb\u4eec\u591a\u7559\u8a00\u8bc4\u8bba\uff0c\u591a\u7ed9\u5efa\u8bae\uff01\u8c22\u8c22\uff01<\/p>\n<p><img decoding=\"async\" src=\"https:\/\/www.17golang.com\/uploads\/20241102\/1730515363672591a3383aa.jpg\" class=\"aligncenter\"><\/p>\n<p><strong>\u8054\u8868\u67e5\u8be2\u7684\u5999\u7528\uff1a\u4ece\u6570\u636e\u5e93\u7684\u5927\u4f6c\u90a3\u91cc\u5b66\u4e60<\/strong><\/p>\n<p>\u5728\u5904\u7406\u591a\u8868\u6570\u636e\u5173\u8054\u65f6\uff0c\u8054\u5408\u67e5\u8be2\u662f\u4e0d\u53ef\u6216\u7f3a\u7684\u624b\u6bb5\u3002\u4eca\u5929\uff0c\u6211\u4eec\u5c31\u5411\u6570\u636e\u5e93\u5927\u4f6c\u8bf7\u6559\u4e00\u4e2a\u8054\u5408\u67e5\u8be2\u7684\u95ee\u9898\u3002<\/p>\n<p>\u95ee\u9898\uff1a\u6211\u4eec\u6709\u4e09\u4e2a\u8868\uff1astrategy\u3001group \u548c strategy_group\uff0c\u5176\u4e2d strategy_group \u662f strategy \u548c group \u7684 id \u8054\u7cfb\u5bf9\u5e94\u8868\u3002<\/p>\n<p>sql \u67e5\u8be2\u8bed\u53e5\uff1a<\/p>\n<pre>select \n    *\nfrom \n    strategy\ninner join \n    strategy_group on strategy.id = strategy_group.strategy_id\ninner join \n    group on strategy_group.group_id = group.id;<\/pre>\n<p>\u6311\u6218\uff1a\u8fd9\u4e2a\u67e5\u8be2\u53ea\u8fd4\u56de\u6709 group \u8054\u7cfb\u7684 strategy \u4fe1\u606f\u3002\u6211\u4eec\u5e0c\u671b\u80fd\u591f\u67e5\u8be2\u6240\u6709 strategy\uff0c\u5373\u4f7f\u5b83\u4eec\u6ca1\u6709\u4e0e group \u8054\u7cfb\uff0c\u5e76\u4e14 gatewaymac \u503c\u5e94\u8be5\u8bbe\u7f6e\u4e3a `null\u3002<\/p>\n<p>\u89e3\u51b3\u529e\u6cd5\uff1a\u5927\u4f6c\u4eec\u5efa\u8bae\u4f7f\u7528 left join\uff0c\u5b83\u53ef\u4ee5\u4fdd\u7559\u88ab\u62fc\u8868\u5b57\u6bb5\u4e3a\u7a7a\u7684\u6570\u636e\u3002\u5f53 left join \u65f6\u6ca1\u6709\u5bf9\u5e94\u503c\u7684\u6570\u636e\u5b57\u6bb5\u5c31\u662f\u7a7a\u503c null\u3002<\/p>\n<p>\u6539\u8fdb\u540e\u7684 sql \u67e5\u8be2\u8bed\u53e5\uff1a<\/p>\n<pre>SELECT \n    strategy.*,\n    IF(gatewaymac IS NULL, 'defaultValue', gatewaymac) AS gatewaymac\nFROM \n    strategy\nLEFT JOIN \n    strategy_group ON strategy.id = strategy_group.strategy_id\nLEFT JOIN \n    group ON strategy_group.group_id = group.id;<\/pre>\n<p>\u8fd9\u4e2a\u67e5\u8be2\u5c06\u8fd4\u56de\u6240\u6709 strategy \u4fe1\u606f\uff0c\u5305\u62ec\u6ca1\u6709\u4e0e group \u8054\u7cfb\u7684 strategy\u3002gatewaymac \u5b57\u6bb5\u5bf9\u4e8e\u6ca1\u6709 group \u8054\u7cfb\u7684 strategy \u5c06\u88ab\u8bbe\u7f6e\u4e3a `defaultvalue\u3002<\/p>\n<p>\u4eca\u5929\u5173\u4e8e\u300a\u5982\u4f55\u4f7f\u7528\u8054\u8868\u67e5\u8be2\u83b7\u53d6\u6240\u6709\u7b56\u7565\u4fe1\u606f\uff0c\u5373\u4f7f\u5b83\u4eec\u6ca1\u6709\u4e0e\u7ec4\u5173\u8054\uff1f\u300b\u7684\u5185\u5bb9\u4ecb\u7ecd\u5c31\u5230\u6b64\u7ed3\u675f\uff0c\u5982\u679c\u6709\u4ec0\u4e48\u7591\u95ee\u6216\u8005\u5efa\u8bae\uff0c\u53ef\u4ee5\u5728\u4e3b\u673a\u5b9d\u8d1d\u516c\u4f17\u53f7\u4e0b\u591a\u591a\u56de\u590d\u4ea4\u6d41\uff1b\u6587\u4e2d\u82e5\u6709\u4e0d\u6b63\u4e4b\u5904\uff0c\u4e5f\u5e0c\u671b\u56de\u590d\u7559\u8a00\u4ee5\u544a\u77e5\uff01<\/p>\n<dl>\n<dt>\n <\/dt>\n<\/dl>\n","protected":false},"excerpt":{"rendered":"<p>\u5982\u4f55\u4f7f\u7528\u8054\u8868\u67e5\u8be2\u83b7\u53d6\u6240\u6709\u7b56\u7565\u4fe1\u606f&#46;&#46;&#46;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[101],"tags":[],"class_list":["post-200336","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/200336","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"}],"author":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/comments?post=200336"}],"version-history":[{"count":0,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/200336\/revisions"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=200336"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=200336"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=200336"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}