{"id":160135,"date":"2024-11-03T20:34:22","date_gmt":"2024-11-03T12:34:22","guid":{"rendered":"https:\/\/server.hk\/cnblog\/160135\/"},"modified":"2024-11-03T20:34:23","modified_gmt":"2024-11-03T12:34:23","slug":"oceanbase-%e6%95%99%e7%a8%8b%ef%bc%9aoceanbase-first_value","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/160135\/","title":{"rendered":"OceanBase \u6559\u7a0b\uff1aOceanBase FIRST_VALUE"},"content":{"rendered":"<h1 id=\"oceanbase-%e6%95%99%e7%a8%8b%ef%bc%9aoceanbase-first_value-bySLqCWeyK\">OceanBase \u6559\u7a0b\uff1aOceanBase FIRST_VALUE<\/h1>\n<p>\u5728\u7576\u4eca\u7684\u6578\u64da\u5eab\u7ba1\u7406\u7cfb\u7d71\u4e2d\uff0cOceanBase \u4f5c\u70ba\u4e00\u500b\u9ad8\u6027\u80fd\u7684\u5206\u4f48\u5f0f\u6578\u64da\u5eab\uff0c\u8d8a\u4f86\u8d8a\u53d7\u5230\u958b\u767c\u8005\u548c\u4f01\u696d\u7684\u9752\u775e\u3002\u5b83\u4e0d\u50c5\u652f\u6301\u9ad8\u4e26\u767c\u7684\u8b80\u5beb\u64cd\u4f5c\uff0c\u9084\u5177\u5099\u5f37\u5927\u7684\u6578\u64da\u8655\u7406\u80fd\u529b\u3002\u672c\u6587\u5c07\u6df1\u5165\u63a2\u8a0e OceanBase \u4e2d\u7684 FIRST_VALUE \u51fd\u6578\uff0c\u5e6b\u52a9\u8b80\u8005\u7406\u89e3\u5176\u7528\u6cd5\u53ca\u61c9\u7528\u5834\u666f\u3002<\/p>\n<h2 id=\"%e4%bb%80%e9%ba%bc%e6%98%af-first_value-%e5%87%bd%e6%95%b8%ef%bc%9f-bySLqCWeyK\">\u4ec0\u9ebc\u662f FIRST_VALUE \u51fd\u6578\uff1f<\/h2>\n<p>FIRST_VALUE \u51fd\u6578\u662f\u4e00\u500b\u7a97\u53e3\u51fd\u6578\uff0c\u7528\u65bc\u8fd4\u56de\u6307\u5b9a\u7a97\u53e3\u5167\u7684\u7b2c\u4e00\u500b\u503c\u3002\u9019\u5728\u9700\u8981\u5c0d\u6578\u64da\u9032\u884c\u5206\u7d44\u4e26\u63d0\u53d6\u6bcf\u7d44\u7684\u9996\u500b\u6578\u64da\u6642\u975e\u5e38\u6709\u7528\u3002\u5b83\u7684\u57fa\u672c\u8a9e\u6cd5\u5982\u4e0b\uff1a<\/p>\n<pre><code>FIRST_VALUE(value_column) OVER (PARTITION BY partition_column ORDER BY order_column [ROWS BETWEEN ...])<\/code><\/pre>\n<p>\u5728\u9019\u88e1\uff0c<code>value_column<\/code> \u662f\u4f60\u60f3\u8981\u63d0\u53d6\u7684\u5217\uff0c<code>partition_column<\/code> \u662f\u7528\u65bc\u5206\u7d44\u7684\u5217\uff0c\u800c <code>order_column<\/code> \u5247\u662f\u7528\u65bc\u6392\u5e8f\u7684\u5217\u3002\u7a97\u53e3\u7684\u7bc4\u570d\u53ef\u4ee5\u901a\u904e <code>ROWS BETWEEN<\/code> \u5b50\u53e5\u9032\u4e00\u6b65\u5b9a\u7fa9\u3002<\/p>\n<h2 id=\"%e4%bd%bf%e7%94%a8%e7%a4%ba%e4%be%8b-bySLqCWeyK\">\u4f7f\u7528\u793a\u4f8b<\/h2>\n<p>\u5047\u8a2d\u6211\u5011\u6709\u4e00\u500b\u540d\u70ba <code>sales<\/code> \u7684\u8868\uff0c\u8a72\u8868\u5305\u542b\u4ee5\u4e0b\u5217\uff1a<\/p>\n<ul>\n<li><code>id<\/code> &#8211; \u92b7\u552e\u8a18\u9304\u7684\u552f\u4e00\u6a19\u8b58<\/li>\n<li><code>product<\/code> &#8211; \u7522\u54c1\u540d\u7a31<\/li>\n<li><code>amount<\/code> &#8211; \u92b7\u552e\u91d1\u984d<\/li>\n<li><code>sale_date<\/code> &#8211; \u92b7\u552e\u65e5\u671f<\/li>\n<\/ul>\n<p>\u6211\u5011\u5e0c\u671b\u67e5\u8a62\u6bcf\u500b\u7522\u54c1\u7684\u7b2c\u4e00\u7b46\u92b7\u552e\u91d1\u984d\u3002\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b SQL \u67e5\u8a62\uff1a<\/p>\n<pre><code>SELECT \n    product,\n    FIRST_VALUE(amount) OVER (PARTITION BY product ORDER BY sale_date) AS first_sale_amount\nFROM \n    sales;<\/code><\/pre>\n<p>\u9019\u6bb5\u67e5\u8a62\u5c07\u8fd4\u56de\u6bcf\u500b\u7522\u54c1\u7684\u7b2c\u4e00\u7b46\u92b7\u552e\u91d1\u984d\uff0c\u6839\u64da\u92b7\u552e\u65e5\u671f\u9032\u884c\u6392\u5e8f\u3002<\/p>\n<h2 id=\"first_value-%e7%9a%84%e6%87%89%e7%94%a8%e5%a0%b4%e6%99%af-bySLqCWeyK\">FIRST_VALUE \u7684\u61c9\u7528\u5834\u666f<\/h2>\n<p>FIRST_VALUE \u51fd\u6578\u5728\u591a\u7a2e\u5834\u666f\u4e2d\u90fd\u80fd\u767c\u63ee\u4f5c\u7528\uff0c\u4ee5\u4e0b\u662f\u5e7e\u500b\u5e38\u898b\u7684\u61c9\u7528\u5834\u666f\uff1a<\/p>\n<ul>\n<li><strong>\u5831\u544a\u751f\u6210\uff1a<\/strong>\u5728\u751f\u6210\u92b7\u552e\u5831\u544a\u6642\uff0c\u53ef\u4ee5\u4f7f\u7528 FIRST_VALUE \u63d0\u53d6\u6bcf\u500b\u7522\u54c1\u7684\u9996\u6b21\u92b7\u552e\u91d1\u984d\uff0c\u5e6b\u52a9\u5206\u6790\u7522\u54c1\u7684\u5e02\u5834\u8868\u73fe\u3002<\/li>\n<li><strong>\u6578\u64da\u5206\u6790\uff1a<\/strong>\u5728\u6578\u64da\u5206\u6790\u4e2d\uff0cFIRST_VALUE \u53ef\u4ee5\u7528\u4f86\u627e\u51fa\u6bcf\u500b\u5ba2\u6236\u7684\u9996\u6b21\u8cfc\u8cb7\u884c\u70ba\uff0c\u9032\u800c\u5236\u5b9a\u91dd\u5c0d\u6027\u7684\u71df\u92b7\u7b56\u7565\u3002<\/li>\n<li><strong>\u6642\u9593\u5e8f\u5217\u5206\u6790\uff1a<\/strong>\u5728\u8655\u7406\u6642\u9593\u5e8f\u5217\u6578\u64da\u6642\uff0c\u53ef\u4ee5\u4f7f\u7528 FIRST_VALUE \u7372\u53d6\u6bcf\u500b\u6642\u9593\u6bb5\u7684\u9996\u500b\u6578\u64da\u9ede\uff0c\u9019\u5c0d\u65bc\u8da8\u52e2\u5206\u6790\u975e\u5e38\u91cd\u8981\u3002<\/li>\n<\/ul>\n<h2 id=\"%e6%b3%a8%e6%84%8f%e4%ba%8b%e9%a0%85-bySLqCWeyK\">\u6ce8\u610f\u4e8b\u9805<\/h2>\n<p>\u5728\u4f7f\u7528 FIRST_VALUE \u51fd\u6578\u6642\uff0c\u6709\u5e7e\u9ede\u9700\u8981\u6ce8\u610f\uff1a<\/p>\n<ul>\n<li>\u78ba\u4fdd <code>ORDER BY<\/code> \u5b50\u53e5\u7684\u6b63\u78ba\u6027\uff0c\u56e0\u70ba\u5b83\u5c07\u5f71\u97ff\u8fd4\u56de\u7684\u7b2c\u4e00\u500b\u503c\u3002<\/li>\n<li>\u5982\u679c\u7a97\u53e3\u5167\u6c92\u6709\u6578\u64da\uff0cFIRST_VALUE \u5c07\u8fd4\u56de NULL\u3002<\/li>\n<li>\u5728\u5927\u578b\u6578\u64da\u96c6\u4e0a\u4f7f\u7528\u7a97\u53e3\u51fd\u6578\u6642\uff0c\u53ef\u80fd\u6703\u5f71\u97ff\u67e5\u8a62\u6027\u80fd\uff0c\u56e0\u6b64\u9700\u8981\u8b39\u614e\u4f7f\u7528\u3002<\/li>\n<\/ul>\n<h2 id=\"%e7%b8%bd%e7%b5%90-bySLqCWeyK\">\u7e3d\u7d50<\/h2>\n<p>OceanBase \u7684 FIRST_VALUE \u51fd\u6578\u662f\u4e00\u500b\u5f37\u5927\u7684\u5de5\u5177\uff0c\u80fd\u5920\u5e6b\u52a9\u958b\u767c\u8005\u5728\u6578\u64da\u5206\u6790\u548c\u5831\u544a\u751f\u6210\u4e2d\u63d0\u53d6\u95dc\u9375\u6578\u64da\u3002\u901a\u904e\u6b63\u78ba\u4f7f\u7528\u9019\u500b\u51fd\u6578\uff0c\u53ef\u4ee5\u63d0\u9ad8\u6578\u64da\u8655\u7406\u7684\u6548\u7387\u548c\u6e96\u78ba\u6027\u3002\u82e5\u60a8\u5c0d\u65bc\u6578\u64da\u5eab\u7ba1\u7406\u6709\u9032\u4e00\u6b65\u7684\u9700\u6c42\uff0c\u8003\u616e\u4f7f\u7528 <a href=\"https:\/\/server.hk\">\u9999\u6e2fVPS<\/a> \u4f86\u642d\u5efa\u60a8\u7684\u6578\u64da\u5eab\u74b0\u5883\uff0c\u4eab\u53d7\u9ad8\u6548\u7a69\u5b9a\u7684\u670d\u52d9\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u5b66\u4e60\u5982\u4f55\u5728 OceanBase \u4e2d\u4f7f\u7528 FIRST_VALUE \u51fd\u6570\uff0c\u83b7\u53d6\u6570\u636e\u96c6\u4e2d\u7684\u9996\u4e2a\u503c\uff0c\u63d0\u5347\u6570\u636e\u67e5\u8be2\u6548\u7387\u4e0e\u51c6\u786e\u6027\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-160135","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/160135","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=160135"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/160135\/revisions"}],"predecessor-version":[{"id":160136,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/160135\/revisions\/160136"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=160135"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=160135"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=160135"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}