{"id":35234,"date":"2024-11-26T14:11:12","date_gmt":"2024-11-26T06:11:12","guid":{"rendered":"https:\/\/fwq.ai\/blog\/35234\/"},"modified":"2024-11-26T14:11:12","modified_gmt":"2024-11-26T06:11:12","slug":"%e5%a6%82%e4%bd%95%e5%b7%a7%e5%a6%99%e6%8e%a7%e5%88%b6java-sql%e6%9f%a5%e8%af%a2%e7%9a%84%e8%bf%94%e5%9b%9e%e5%ad%97%e6%ae%b5%e6%95%b0%e9%87%8f%ef%bc%9f","status":"publish","type":"post","link":"https:\/\/fwq.ai\/blog\/35234\/","title":{"rendered":"\u5982\u4f55\u5de7\u5999\u63a7\u5236Java SQL\u67e5\u8be2\u7684\u8fd4\u56de\u5b57\u6bb5\u6570\u91cf\uff1f"},"content":{"rendered":"<p><img decoding=\"async\" src=\"https:\/\/img.php.cn\/upload\/article\/001\/246\/273\/173064223979439.jpg\" class=\"aligncenter\" title=\"\u5982\u4f55\u5de7\u5999\u63a7\u5236Java SQL\u67e5\u8be2\u7684\u8fd4\u56de\u5b57\u6bb5\u6570\u91cf\uff1f\u63d2\u56fe\" alt=\"\u5982\u4f55\u5de7\u5999\u63a7\u5236Java SQL\u67e5\u8be2\u7684\u8fd4\u56de\u5b57\u6bb5\u6570\u91cf\uff1f\u63d2\u56fe\" \/><\/p>\n<p><strong>Java SQL\u67e5\u8be2\uff1a\u5de7\u5999\u63a7\u5236\u8fd4\u56de\u5b57\u6bb5<\/strong><\/p>\n<p>\u5728\u8fdb\u884cSQL\u67e5\u8be2\u65f6\uff0c\u6211\u4eec\u7ecf\u5e38\u9700\u8981\u4ece\u591a\u4e2a\u8868\u4e2d\u83b7\u53d6\u7279\u5b9a\u5b57\u6bb5\u3002\u7136\u800c\uff0c\u5982\u679c\u8fd4\u56de\u5b57\u6bb5\u6570\u91cf\u8fc7\u591a\uff0c\u5219\u4f1a\u5f71\u54cd\u6548\u7387\uff0c\u800c\u8fd4\u56de\u5b57\u6bb5\u6570\u91cf\u4e0d\u8db3\uff0c\u53c8\u65e0\u6cd5\u6ee1\u8db3\u9700\u6c42\u3002\u672c\u7bc7\u6587\u7ae0\u5c06\u4ecb\u7ecd\u5982\u4f55\u5de7\u5999\u63a7\u5236\u8fd4\u56de\u5b57\u6bb5\u6570\u91cf\uff0c\u786e\u4fdd\u67e5\u8be2\u7ed3\u679c\u65e2\u51c6\u786e\u53c8\u9ad8\u6548\u3002<\/p>\n<p>\u95ee\u9898\u4e2d\u9047\u5230\u8fd9\u6837\u7684\u60c5\u51b5\uff1a\u4ece\u591a\u4e2a\u8868\u67e5\u8be2\u5b57\u6bb5\u65f6\uff0c\u5bf9\u4e8e\u67d0\u4e9b\u5b57\u6bb5\uff08\u5982status\uff09\uff0c\u5982\u679c\u660e\u786e\u6307\u5b9a\u5728\u67e5\u8be2\u4e2d\uff0c\u5219\u4f1a\u5728\u7ed3\u679c\u4e2d\u51fa\u73b0\uff1b\u4f46\u5982\u679c\u672a\u6307\u5b9a\uff0c\u5219\u4f1a\u5728\u7ed3\u679c\u4e2d\u8fd4\u56denull\u503c\u3002\u800c\u5bf9\u4e8ename\u5b57\u6bb5\uff0c\u65e0\u8bba\u662f\u5426\u5728\u67e5\u8be2\u4e2d\u6307\u5b9a\uff0c\u90fd\u4e0d\u4f1a\u51fa\u73b0\u5728\u7ed3\u679c\u4e2d\u3002<\/p>\n<p>\u8981\u89e3\u51b3\u8fd9\u4e2a\u95ee\u9898\uff0c\u9700\u8981\u4f7f\u7528SQL\u5173\u952e\u5b57<strong>LEFT JOIN<\/strong>\u3002LEFT JOIN\u5141\u8bb8\u6211\u4eec\u4ece\u5de6\u8868\uff08\u5373\u7b2c\u4e00\u4e2a\u8868\uff09\u4e2d\u83b7\u53d6\u6240\u6709\u884c\uff0c\u5373\u4f7f\u5728\u53f3\u8868\uff08\u5373\u7b2c\u4e8c\u4e2a\u8868\uff09\u4e2d\u6ca1\u6709\u5339\u914d\u7684\u884c\u3002\u56e0\u6b64\uff0c\u5bf9\u4e8estatus\u5b57\u6bb5\uff0c\u6211\u4eec\u53ef\u4ee5\u4f7f\u7528LEFT JOIN\u5c06\u5de6\u8868\u548c\u53f3\u8868\u8fde\u63a5\u8d77\u6765\uff0c\u5e76\u4f7f\u7528<strong>IS NULL<\/strong>\u6761\u4ef6\u6765\u8fc7\u6ee4\u51fa\u53f3\u8868\u4e2dstatus\u5b57\u6bb5\u4e3anull\u7684\u884c\u3002\u8fd9\u6837\uff0c\u5728\u7ed3\u679c\u4e2d\u5c31\u4e0d\u4f1a\u51fa\u73b0\u5bf9\u4e8estatus\u5b57\u6bb5\u7684null\u503c\u3002<\/p>\n<p><span>\u7acb\u5373\u5b66\u4e60<\/span>\u201c\u201d\uff1b<\/p>\n<p>\u800c\u5bf9\u4e8ename\u5b57\u6bb5\uff0c\u7531\u4e8e\u5728\u67e5\u8be2\u4e2d\u672a\u6307\u5b9a\uff0c\u56e0\u6b64\u4e0d\u4f1a\u51fa\u73b0\u5728\u7ed3\u679c\u4e2d\u3002\u8981\u8fd4\u56dename\u5b57\u6bb5\uff0c\u53ea\u9700\u8981\u5728\u67e5\u8be2\u4e2d\u660e\u786e\u6307\u5b9a\u5373\u53ef\u3002<\/p>\n<p>\u7efc\u4e0a\uff0c\u53ef\u4ee5\u901a\u8fc7\u5de7\u5999\u4f7f\u7528LEFT JOIN\u548cIS NULL\u6761\u4ef6\uff0c\u4ee5\u53ca\u5728\u67e5\u8be2\u4e2d\u660e\u786e\u6307\u5b9a\u6240\u9700\u7684\u5b57\u6bb5\uff0c\u6765\u7075\u6d3b\u63a7\u5236\u8fd4\u56de\u5b57\u6bb5\u7684\u6570\u91cf\uff0c\u4f7f\u67e5\u8be2\u7ed3\u679c\u65e2\u51c6\u786e\u53c8\u9ad8\u6548\u3002<\/p>\n<p>\u4ee5\u4e0a\u5c31\u662f\u5982\u4f55\u5de7\u5999\u63a7\u5236Java SQL\u67e5\u8be2\u7684\u8fd4\u56de\u5b57\u6bb5\u6570\u91cf\uff1f\u7684\u8be6\u7ec6\u5185\u5bb9\uff0c\u66f4\u591a\u8bf7\u5173\u6ce8\u7c73\u4e91\u5176\u5b83\u76f8\u5173\u6587\u7ae0\uff01<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Java SQL\u67e5\u8be2\uff1a\u5de7\u5999\u63a7\u5236\u8fd4\u56de\u5b57\u6bb5 \u5728\u8fdb\u884cSQL\u67e5\u8be2\u65f6\uff0c\u6211\u4eec\u7ecf\u5e38\u9700\u8981\u4ece\u591a\u4e2a\u8868\u4e2d\u83b7\u53d6\u7279\u5b9a\u5b57\u6bb5\u3002\u7136\u800c\uff0c\u5982\u679c\u8fd4\u56de\u5b57\u6bb5\u6570\u91cf\u8fc7\u591a\uff0c\u5219\u4f1a\u5f71\u54cd\u6548\u7387\uff0c\u800c\u8fd4\u56de\u5b57\u6bb5\u6570\u91cf\u4e0d\u8db3\uff0c\u53c8\u65e0\u6cd5\u6ee1\u8db3\u9700\u6c42\u3002\u672c\u7bc7\u6587\u7ae0\u5c06\u4ecb\u7ecd\u5982\u4f55\u5de7\u5999\u63a7\u5236\u8fd4\u56de\u5b57\u6bb5\u6570\u91cf\uff0c\u786e\u4fdd\u67e5\u8be2\u7ed3\u679c\u65e2\u51c6\u786e\u53c8\u9ad8\u6548\u3002 \u95ee\u9898\u4e2d\u9047\u5230\u8fd9\u6837\u7684\u60c5\u51b5\uff1a\u4ece\u591a\u4e2a\u8868\u67e5\u8be2\u5b57\u6bb5\u65f6\uff0c\u5bf9\u4e8e\u67d0\u4e9b\u5b57\u6bb5\uff08\u5982status\uff09\uff0c\u5982\u679c\u660e\u786e\u6307\u5b9a\u5728\u67e5\u8be2\u4e2d\uff0c\u5219\u4f1a\u5728\u7ed3\u679c\u4e2d\u51fa\u73b0\uff1b\u4f46\u5982\u679c\u672a\u6307\u5b9a\uff0c\u5219\u4f1a\u5728\u7ed3\u679c\u4e2d\u8fd4\u56denull\u503c\u3002\u800c\u5bf9\u4e8ename\u5b57\u6bb5\uff0c\u65e0\u8bba\u662f\u5426\u5728\u67e5\u8be2\u4e2d\u6307\u5b9a\uff0c\u90fd\u4e0d\u4f1a\u51fa\u73b0\u5728\u7ed3\u679c\u4e2d\u3002 \u8981\u89e3\u51b3\u8fd9\u4e2a\u95ee\u9898\uff0c\u9700\u8981\u4f7f\u7528SQL\u5173\u952e\u5b57LEFT JOIN\u3002LEFT JOIN\u5141\u8bb8\u6211\u4eec\u4ece\u5de6\u8868\uff08\u5373\u7b2c\u4e00\u4e2a\u8868\uff09\u4e2d\u83b7\u53d6\u6240\u6709\u884c\uff0c\u5373\u4f7f\u5728\u53f3\u8868\uff08\u5373\u7b2c\u4e8c\u4e2a\u8868\uff09\u4e2d\u6ca1\u6709\u5339\u914d\u7684\u884c\u3002\u56e0\u6b64\uff0c\u5bf9\u4e8estatus\u5b57\u6bb5\uff0c\u6211\u4eec\u53ef\u4ee5\u4f7f\u7528LEFT JOIN\u5c06\u5de6\u8868\u548c\u53f3\u8868\u8fde\u63a5\u8d77\u6765\uff0c\u5e76\u4f7f\u7528IS NULL\u6761\u4ef6\u6765\u8fc7\u6ee4\u51fa\u53f3\u8868\u4e2dstatus\u5b57\u6bb5\u4e3anull\u7684\u884c\u3002\u8fd9\u6837\uff0c\u5728\u7ed3\u679c\u4e2d\u5c31\u4e0d\u4f1a\u51fa\u73b0\u5bf9\u4e8estatus\u5b57\u6bb5\u7684null\u503c\u3002 \u7acb\u5373\u5b66\u4e60\u201c\u201d\uff1b \u800c\u5bf9\u4e8ename\u5b57\u6bb5\uff0c\u7531\u4e8e\u5728\u67e5\u8be2\u4e2d\u672a\u6307\u5b9a\uff0c\u56e0\u6b64\u4e0d\u4f1a\u51fa\u73b0\u5728\u7ed3\u679c\u4e2d\u3002\u8981\u8fd4\u56dename\u5b57\u6bb5\uff0c\u53ea\u9700\u8981\u5728\u67e5\u8be2\u4e2d\u660e\u786e\u6307\u5b9a\u5373\u53ef\u3002 \u7efc\u4e0a\uff0c\u53ef\u4ee5\u901a\u8fc7\u5de7\u5999\u4f7f\u7528LEFT JOIN\u548cIS NULL\u6761\u4ef6\uff0c\u4ee5\u53ca\u5728\u67e5\u8be2\u4e2d\u660e\u786e\u6307\u5b9a\u6240\u9700\u7684\u5b57\u6bb5\uff0c\u6765\u7075\u6d3b\u63a7\u5236\u8fd4\u56de\u5b57\u6bb5\u7684\u6570\u91cf\uff0c\u4f7f\u67e5\u8be2\u7ed3\u679c\u65e2\u51c6\u786e\u53c8\u9ad8\u6548\u3002 \u4ee5\u4e0a\u5c31\u662f\u5982\u4f55\u5de7\u5999\u63a7\u5236Java SQL\u67e5\u8be2\u7684\u8fd4\u56de\u5b57\u6bb5\u6570\u91cf\uff1f\u7684\u8be6\u7ec6\u5185\u5bb9\uff0c\u66f4\u591a\u8bf7\u5173\u6ce8\u7c73\u4e91\u5176\u5b83\u76f8\u5173\u6587\u7ae0\uff01<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[16],"tags":[],"class_list":["post-35234","post","type-post","status-publish","format-standard","hentry","category-16"],"_links":{"self":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts\/35234","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/comments?post=35234"}],"version-history":[{"count":0,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts\/35234\/revisions"}],"wp:attachment":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/media?parent=35234"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/categories?post=35234"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/tags?post=35234"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}