{"id":160143,"date":"2024-11-03T20:38:19","date_gmt":"2024-11-03T12:38:19","guid":{"rendered":"https:\/\/server.hk\/cnblog\/160143\/"},"modified":"2024-11-03T20:38:20","modified_gmt":"2024-11-03T12:38:20","slug":"oceanbase-%e6%95%99%e7%a8%8b%ef%bc%9aoceanbase-greatest","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/160143\/","title":{"rendered":"OceanBase \u6559\u7a0b\uff1aOceanBase GREATEST"},"content":{"rendered":"<h1 id=\"oceanbase-%e6%95%99%e7%a8%8b%ef%bc%9aoceanbase-greatest-YeWZnHUYWx\">OceanBase \u6559\u7a0b\uff1aOceanBase GREATEST<\/h1>\n<p>\u5728\u7576\u4eca\u7684\u6578\u64da\u5eab\u6280\u8853\u4e2d\uff0cOceanBase \u4f5c\u70ba\u4e00\u500b\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\u652f\u6301\u5927\u898f\u6a21\u7684\u5728\u7dda\u4ea4\u6613\u8655\u7406\uff08OLTP\uff09\u548c\u5728\u7dda\u5206\u6790\u8655\u7406\uff08OLAP\uff09\u3002\u5728\u9019\u7bc7\u6587\u7ae0\u4e2d\uff0c\u6211\u5011\u5c07\u6df1\u5165\u63a2\u8a0e OceanBase \u4e2d\u7684 GREATEST \u51fd\u6578\uff0c\u4e26\u63d0\u4f9b\u4e00\u4e9b\u5be6\u7528\u7684\u793a\u4f8b\u4f86\u5e6b\u52a9\u60a8\u66f4\u597d\u5730\u7406\u89e3\u5176\u7528\u6cd5\u3002<\/p>\n<h2 id=\"%e4%bb%80%e9%ba%bc%e6%98%af-greatest-%e5%87%bd%e6%95%b8%ef%bc%9f-YeWZnHUYWx\">\u4ec0\u9ebc\u662f GREATEST \u51fd\u6578\uff1f<\/h2>\n<p>GREATEST \u51fd\u6578\u662f\u4e00\u500b\u7528\u65bc\u6bd4\u8f03\u591a\u500b\u503c\u4e26\u8fd4\u56de\u5176\u4e2d\u6700\u5927\u7684\u503c\u7684 SQL \u51fd\u6578\u3002\u5728 OceanBase \u4e2d\uff0c\u9019\u500b\u51fd\u6578\u53ef\u4ee5\u7528\u4f86\u8655\u7406\u6578\u5b57\u3001\u65e5\u671f\u548c\u5b57\u7b26\u4e32\u7b49\u6578\u64da\u985e\u578b\u3002\u9019\u4f7f\u5f97 GREATEST \u51fd\u6578\u5728\u6578\u64da\u67e5\u8a62\u548c\u5831\u544a\u4e2d\u975e\u5e38\u6709\u7528\uff0c\u7279\u5225\u662f\u5728\u9700\u8981\u5f9e\u591a\u500b\u5019\u9078\u503c\u4e2d\u9078\u64c7\u6700\u5927\u503c\u7684\u60c5\u6cc1\u4e0b\u3002<\/p>\n<h2 id=\"greatest-%e5%87%bd%e6%95%b8%e7%9a%84%e8%aa%9e%e6%b3%95-YeWZnHUYWx\">GREATEST \u51fd\u6578\u7684\u8a9e\u6cd5<\/h2>\n<pre><code>GREATEST(value1, value2, ..., valueN)<\/code><\/pre>\n<p>\u5728\u9019\u88e1\uff0cvalue1\u3001value2 \u5230 valueN \u662f\u8981\u9032\u884c\u6bd4\u8f03\u7684\u503c\u3002GREATEST \u51fd\u6578\u5c07\u8fd4\u56de\u9019\u4e9b\u503c\u4e2d\u7684\u6700\u5927\u8005\u3002\u5982\u679c\u6240\u6709\u7684\u503c\u90fd\u662f NULL\uff0c\u5247\u8fd4\u56de NULL\u3002<\/p>\n<h2 id=\"%e4%bd%bf%e7%94%a8-greatest-%e5%87%bd%e6%95%b8%e7%9a%84%e7%a4%ba%e4%be%8b-YeWZnHUYWx\">\u4f7f\u7528 GREATEST \u51fd\u6578\u7684\u793a\u4f8b<\/h2>\n<h3 id=\"%e7%a4%ba%e4%be%8b-1%ef%bc%9a%e6%af%94%e8%bc%83%e6%95%b8%e5%ad%97-YeWZnHUYWx\">\u793a\u4f8b 1\uff1a\u6bd4\u8f03\u6578\u5b57<\/h3>\n<p>\u5047\u8a2d\u6211\u5011\u6709\u4e00\u500b\u540d\u70ba <code>sales<\/code> \u7684\u8868\uff0c\u8a72\u8868\u5305\u542b\u4e0d\u540c\u7522\u54c1\u7684\u92b7\u552e\u6578\u64da\u3002\u6211\u5011\u60f3\u8981\u627e\u51fa\u6bcf\u500b\u7522\u54c1\u7684\u6700\u9ad8\u92b7\u552e\u984d\u3002\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b\u67e5\u8a62\uff1a<\/p>\n<pre><code>SELECT product_id, GREATEST(sales_q1, sales_q2, sales_q3) AS max_sales\nFROM sales;<\/code><\/pre>\n<p>\u9019\u500b\u67e5\u8a62\u5c07\u8fd4\u56de\u6bcf\u500b\u7522\u54c1\u5728\u4e09\u500b\u5b63\u5ea6\u4e2d\u7684\u6700\u9ad8\u92b7\u552e\u984d\u3002<\/p>\n<h3 id=\"%e7%a4%ba%e4%be%8b-2%ef%bc%9a%e6%af%94%e8%bc%83%e6%97%a5%e6%9c%9f-YeWZnHUYWx\">\u793a\u4f8b 2\uff1a\u6bd4\u8f03\u65e5\u671f<\/h3>\n<p>\u5982\u679c\u6211\u5011\u60f3\u8981\u627e\u51fa\u67d0\u500b\u4e8b\u4ef6\u7684\u6700\u65b0\u65e5\u671f\uff0c\u53ef\u4ee5\u4f7f\u7528 GREATEST \u51fd\u6578\u4f86\u6bd4\u8f03\u591a\u500b\u65e5\u671f\u3002\u4f8b\u5982\uff1a<\/p>\n<pre><code>SELECT event_id, GREATEST(start_date, end_date) AS latest_date\nFROM events;<\/code><\/pre>\n<p>\u9019\u5c07\u8fd4\u56de\u6bcf\u500b\u4e8b\u4ef6\u7684\u6700\u65b0\u65e5\u671f\uff0c\u7121\u8ad6\u662f\u958b\u59cb\u65e5\u671f\u9084\u662f\u7d50\u675f\u65e5\u671f\u3002<\/p>\n<h3 id=\"%e7%a4%ba%e4%be%8b-3%ef%bc%9a%e6%af%94%e8%bc%83%e5%ad%97%e7%ac%a6%e4%b8%b2-YeWZnHUYWx\">\u793a\u4f8b 3\uff1a\u6bd4\u8f03\u5b57\u7b26\u4e32<\/h3>\n<p>GREATEST \u51fd\u6578\u4e5f\u53ef\u4ee5\u7528\u65bc\u5b57\u7b26\u4e32\u6bd4\u8f03\uff0c\u6839\u64da\u5b57\u6bcd\u9806\u5e8f\u8fd4\u56de\u6700\u5927\u503c\u3002\u4f8b\u5982\uff1a<\/p>\n<pre><code>SELECT GREATEST('apple', 'banana', 'cherry') AS max_fruit;<\/code><\/pre>\n<p>\u9019\u5c07\u8fd4\u56de <code>cherry<\/code>\uff0c\u56e0\u70ba\u5728\u5b57\u6bcd\u9806\u5e8f\u4e2d\u5b83\u662f\u6700\u5927\u7684\u3002<\/p>\n<h2 id=\"%e6%b3%a8%e6%84%8f%e4%ba%8b%e9%a0%85-YeWZnHUYWx\">\u6ce8\u610f\u4e8b\u9805<\/h2>\n<p>\u5728\u4f7f\u7528 GREATEST \u51fd\u6578\u6642\uff0c\u6709\u5e7e\u9ede\u9700\u8981\u6ce8\u610f\uff1a<\/p>\n<ul>\n<li>\u5982\u679c\u4efb\u4f55\u4e00\u500b\u503c\u70ba NULL\uff0c\u5247 GREATEST \u51fd\u6578\u5c07\u5ffd\u7565\u8a72\u503c\u3002<\/li>\n<li>\u5c0d\u65bc\u5b57\u7b26\u4e32\u6bd4\u8f03\uff0cGREATEST \u51fd\u6578\u662f\u57fa\u65bc\u5b57\u6bcd\u9806\u5e8f\u9032\u884c\u6bd4\u8f03\u7684\u3002<\/li>\n<li>\u5728\u8655\u7406\u65e5\u671f\u6642\uff0c\u78ba\u4fdd\u65e5\u671f\u683c\u5f0f\u4e00\u81f4\uff0c\u4ee5\u907f\u514d\u4e0d\u5fc5\u8981\u7684\u932f\u8aa4\u3002<\/li>\n<\/ul>\n<h2 id=\"%e7%b8%bd%e7%b5%90-YeWZnHUYWx\">\u7e3d\u7d50<\/h2>\n<p>OceanBase \u7684 GREATEST \u51fd\u6578\u662f\u4e00\u500b\u5f37\u5927\u7684\u5de5\u5177\uff0c\u53ef\u4ee5\u5e6b\u52a9\u958b\u767c\u8005\u5728\u6578\u64da\u67e5\u8a62\u4e2d\u5feb\u901f\u627e\u5230\u6700\u5927\u503c\u3002\u7121\u8ad6\u662f\u8655\u7406\u6578\u5b57\u3001\u65e5\u671f\u9084\u662f\u5b57\u7b26\u4e32\uff0cGREATEST \u51fd\u6578\u90fd\u80fd\u63d0\u4f9b\u6709\u6548\u7684\u89e3\u6c7a\u65b9\u6848\u3002\u5c0d\u65bc\u9700\u8981\u9ad8\u6548\u6578\u64da\u8655\u7406\u7684\u4f01\u696d\u4f86\u8aaa\uff0c\u9078\u64c7\u5408\u9069\u7684\u6578\u64da\u5eab\u7cfb\u7d71\u81f3\u95dc\u91cd\u8981\u3002\u5982\u679c\u60a8\u6b63\u5728\u5c0b\u627e\u53ef\u9760\u7684 <a href=\"https:\/\/server.hk\">\u9999\u6e2fVPS<\/a> \u89e3\u6c7a\u65b9\u6848\uff0cServer.HK \u63d0\u4f9b\u591a\u7a2e\u9078\u64c7\u4ee5\u6eff\u8db3\u60a8\u7684\u9700\u6c42\u3002\u7121\u8ad6\u662f <a href=\"https:\/\/server.hk\">\u96f2\u4f3a\u670d\u5668<\/a> \u9084\u662f <a href=\"https:\/\/server.hk\">\u9999\u6e2f\u4f3a\u670d\u5668<\/a>\uff0c\u6211\u5011\u90fd\u80fd\u70ba\u60a8\u63d0\u4f9b\u7a69\u5b9a\u7684\u6027\u80fd\u548c\u512a\u8cea\u7684\u670d\u52d9\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Discover how to use OceanBase GREATEST in our comprehensive tutorial, enhancing your database skills with practical examples and expert tips.<\/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-160143","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/160143","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=160143"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/160143\/revisions"}],"predecessor-version":[{"id":160144,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/160143\/revisions\/160144"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=160143"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=160143"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=160143"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}