{"id":160525,"date":"2024-11-03T22:49:17","date_gmt":"2024-11-03T14:49:17","guid":{"rendered":"https:\/\/server.hk\/cnblog\/160525\/"},"modified":"2024-11-03T22:49:18","modified_gmt":"2024-11-03T14:49:18","slug":"oceanbase-%e6%95%99%e7%a8%8b%ef%bc%9aoceanbase-%e7%a9%ba%e6%a2%9d%e4%bb%b6","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/160525\/","title":{"rendered":"OceanBase \u6559\u7a0b\uff1aOceanBase \u7a7a\u689d\u4ef6"},"content":{"rendered":"<h1 id=\"oceanbase-%e6%95%99%e7%a8%8b%ef%bc%9aoceanbase-%e7%a9%ba%e6%a2%9d%e4%bb%b6-pAXfykIEgo\">OceanBase \u6559\u7a0b\uff1aOceanBase \u7a7a\u689d\u4ef6<\/h1>\n<p>\u5728\u7576\u4eca\u7684\u6578\u64da\u5eab\u6280\u8853\u4e2d\uff0cOceanBase \u4f5c\u70ba\u4e00\u6b3e\u9ad8\u6027\u80fd\u7684\u5206\u4f48\u5f0f\u6578\u64da\u5eab\u7cfb\u7d71\uff0c\u8d8a\u4f86\u8d8a\u53d7\u5230\u958b\u767c\u8005\u548c\u4f01\u696d\u7684\u9752\u775e\u3002\u5b83\u7531\u963f\u91cc\u5df4\u5df4\u96c6\u5718\u958b\u767c\uff0c\u65e8\u5728\u89e3\u6c7a\u5927\u898f\u6a21\u6578\u64da\u8655\u7406\u7684\u9700\u6c42\u3002\u672c\u6587\u5c07\u6df1\u5165\u63a2\u8a0e OceanBase \u7684\u7a7a\u689d\u4ef6\uff08NULL Condition\uff09\u53ca\u5176\u5728\u67e5\u8a62\u4e2d\u7684\u61c9\u7528\u3002<\/p>\n<h2 id=\"%e4%bb%80%e9%ba%bc%e6%98%af%e7%a9%ba%e6%a2%9d%e4%bb%b6%ef%bc%88null-condition%ef%bc%89%ef%bc%9f-pAXfykIEgo\">\u4ec0\u9ebc\u662f\u7a7a\u689d\u4ef6\uff08NULL Condition\uff09\uff1f<\/h2>\n<p>\u5728\u6578\u64da\u5eab\u4e2d\uff0c\u7a7a\u689d\u4ef6\u662f\u6307\u4e00\u500b\u5b57\u6bb5\u7684\u503c\u70ba NULL\uff0c\u9019\u8868\u793a\u8a72\u5b57\u6bb5\u6c92\u6709\u4efb\u4f55\u6578\u64da\u3002NULL \u8207\u7a7a\u5b57\u7b26\u4e32\u6216\u96f6\u4e0d\u540c\uff0c\u5b83\u4ee3\u8868\u7f3a\u5931\u7684\u6578\u64da\u3002\u5728 OceanBase \u4e2d\uff0c\u8655\u7406 NULL \u503c\u662f\u975e\u5e38\u91cd\u8981\u7684\uff0c\u56e0\u70ba\u5b83\u5011\u53ef\u80fd\u5f71\u97ff\u67e5\u8a62\u7684\u7d50\u679c\u548c\u6027\u80fd\u3002<\/p>\n<h2 id=\"oceanbase-%e4%b8%ad%e7%9a%84-null-%e5%80%bc%e8%99%95%e7%90%86-pAXfykIEgo\">OceanBase \u4e2d\u7684 NULL \u503c\u8655\u7406<\/h2>\n<p>\u5728 OceanBase \u4e2d\uff0cNULL \u503c\u7684\u8655\u7406\u9075\u5faa SQL \u6a19\u6e96\u3002\u4ee5\u4e0b\u662f\u4e00\u4e9b\u5e38\u898b\u7684 NULL \u503c\u8655\u7406\u65b9\u6cd5\uff1a<\/p>\n<ul>\n<li><strong>IS NULL \u548c IS NOT NULL<\/strong>\uff1a\u9019\u662f\u6aa2\u67e5\u5b57\u6bb5\u662f\u5426\u70ba NULL \u7684\u57fa\u672c\u65b9\u6cd5\u3002<\/li>\n<li><strong>COALESCE \u51fd\u6578<\/strong>\uff1a\u8a72\u51fd\u6578\u8fd4\u56de\u7b2c\u4e00\u500b\u975e NULL \u7684\u503c\uff0c\u5e38\u7528\u65bc\u66ff\u4ee3 NULL \u503c\u3002<\/li>\n<li><strong>NULLIF \u51fd\u6578<\/strong>\uff1a\u8a72\u51fd\u6578\u6bd4\u8f03\u5169\u500b\u8868\u9054\u5f0f\uff0c\u5982\u679c\u76f8\u7b49\u5247\u8fd4\u56de NULL\uff0c\u5426\u5247\u8fd4\u56de\u7b2c\u4e00\u500b\u8868\u9054\u5f0f\u3002<\/li>\n<\/ul>\n<h2 id=\"%e4%bd%bf%e7%94%a8%e7%a4%ba%e4%be%8b-pAXfykIEgo\">\u4f7f\u7528\u793a\u4f8b<\/h2>\n<p>\u4ee5\u4e0b\u662f\u4e00\u4e9b\u5728 OceanBase \u4e2d\u4f7f\u7528\u7a7a\u689d\u4ef6\u7684 SQL \u67e5\u8a62\u793a\u4f8b\uff1a<\/p>\n<pre><code>-- \u67e5\u8a62\u6240\u6709\u5b57\u6bb5\u70ba NULL \u7684\u8a18\u9304\nSELECT * FROM users WHERE email IS NULL;\n\n-- \u4f7f\u7528 COALESCE \u51fd\u6578\u66ff\u4ee3 NULL \u503c\nSELECT id, COALESCE(email, '\u672a\u63d0\u4f9b') AS email FROM users;\n\n-- \u4f7f\u7528 NULLIF \u51fd\u6578\nSELECT id, NULLIF(phone, '') AS phone FROM users;<\/code><\/pre>\n<h2 id=\"%e7%a9%ba%e6%a2%9d%e4%bb%b6%e7%9a%84%e6%80%a7%e8%83%bd%e8%80%83%e9%87%8f-pAXfykIEgo\">\u7a7a\u689d\u4ef6\u7684\u6027\u80fd\u8003\u91cf<\/h2>\n<p>\u5728\u8655\u7406\u5927\u91cf\u6578\u64da\u6642\uff0cNULL \u503c\u53ef\u80fd\u6703\u5f71\u97ff\u67e5\u8a62\u6027\u80fd\u3002\u4ee5\u4e0b\u662f\u4e00\u4e9b\u512a\u5316\u5efa\u8b70\uff1a<\/p>\n<ul>\n<li><strong>\u7d22\u5f15\u8a2d\u8a08<\/strong>\uff1a\u5728\u8a2d\u8a08\u7d22\u5f15\u6642\uff0c\u8003\u616e\u5230 NULL \u503c\u7684\u5f71\u97ff\uff0c\u907f\u514d\u5728\u7d93\u5e38\u70ba NULL \u7684\u5b57\u6bb5\u4e0a\u5efa\u7acb\u7d22\u5f15\u3002<\/li>\n<li><strong>\u67e5\u8a62\u512a\u5316<\/strong>\uff1a\u5728\u67e5\u8a62\u4e2d\u76e1\u91cf\u907f\u514d\u4f7f\u7528 IS NULL\uff0c\u7279\u5225\u662f\u5728\u5927\u8868\u4e2d\uff0c\u9019\u53ef\u80fd\u6703\u5c0e\u81f4\u5168\u8868\u6383\u63cf\u3002<\/li>\n<li><strong>\u6578\u64da\u6e05\u7406<\/strong>\uff1a\u5b9a\u671f\u6aa2\u67e5\u548c\u6e05\u7406 NULL \u503c\uff0c\u78ba\u4fdd\u6578\u64da\u7684\u5b8c\u6574\u6027\u548c\u6e96\u78ba\u6027\u3002<\/li>\n<\/ul>\n<h2 id=\"%e7%b5%90%e8%ab%96-pAXfykIEgo\">\u7d50\u8ad6<\/h2>\n<p>OceanBase \u4f5c\u70ba\u4e00\u6b3e\u5f37\u5927\u7684\u5206\u4f48\u5f0f\u6578\u64da\u5eab\u7cfb\u7d71\uff0c\u5c0d\u65bc\u7a7a\u689d\u4ef6\u7684\u8655\u7406\u81f3\u95dc\u91cd\u8981\u3002\u4e86\u89e3\u5982\u4f55\u6709\u6548\u5730\u8655\u7406 NULL \u503c\uff0c\u4e0d\u50c5\u80fd\u63d0\u9ad8\u67e5\u8a62\u7684\u6e96\u78ba\u6027\uff0c\u9084\u80fd\u512a\u5316\u6027\u80fd\u3002\u96a8\u8457\u6578\u64da\u91cf\u7684\u589e\u9577\uff0c\u5c0d\u65bc NULL \u503c\u7684\u7ba1\u7406\u5c07\u6210\u70ba\u6578\u64da\u5eab\u7ba1\u7406\u4e2d\u7684\u4e00\u500b\u91cd\u8981\u8ab2\u984c\u3002<\/p>\n<p>\u5982\u679c\u60a8\u5c0d\u65bc <a href=\"https:\/\/server.hk\">\u9999\u6e2f VPS<\/a> \u670d\u52d9\u6709\u8208\u8da3\uff0c\u6216\u60f3\u4e86\u89e3\u66f4\u591a\u95dc\u65bc <a href=\"https:\/\/server.hk\">\u96f2\u4f3a\u670d\u5668<\/a> \u7684\u8cc7\u8a0a\uff0c\u6b61\u8fce\u8a2a\u554f\u6211\u5011\u7684\u7db2\u7ad9\u4ee5\u7372\u53d6\u66f4\u591a\u8a73\u7d30\u8cc7\u6599\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u63a2\u7d22 OceanBase \u6559\u7a0b\uff0c\u4e86\u89e3\u5982\u4f55\u4f7f\u7528\u7a7a\u689d\u4ef6\u9032\u884c\u9ad8\u6548\u67e5\u8a62\uff0c\u63d0\u5347\u6578\u64da\u5eab\u6027\u80fd\u8207\u7ba1\u7406\u6280\u5de7\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-160525","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/160525","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=160525"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/160525\/revisions"}],"predecessor-version":[{"id":160526,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/160525\/revisions\/160526"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=160525"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=160525"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=160525"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}