{"id":160161,"date":"2024-11-03T20:47:19","date_gmt":"2024-11-03T12:47:19","guid":{"rendered":"https:\/\/server.hk\/cnblog\/160161\/"},"modified":"2024-11-03T20:47:20","modified_gmt":"2024-11-03T12:47:20","slug":"oceanbase-%e6%95%99%e7%a8%8b%ef%bc%9aoceanbase-length","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/160161\/","title":{"rendered":"OceanBase \u6559\u7a0b\uff1aOceanBase LENGTH"},"content":{"rendered":"<h1 id=\"oceanbase-%e6%95%99%e7%a8%8b%ef%bc%9aoceanbase-length-ieMCLqKARp\">OceanBase \u6559\u7a0b\uff1aOceanBase LENGTH<\/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\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 LENGTH \u51fd\u6578\uff0c\u4e26\u63d0\u4f9b\u4e00\u4e9b\u5be6\u7528\u7684\u793a\u4f8b\u548c\u61c9\u7528\u5834\u666f\u3002<\/p>\n<h2 id=\"%e4%bb%80%e9%ba%bc%e6%98%af-length-%e5%87%bd%e6%95%b8%ef%bc%9f-ieMCLqKARp\">\u4ec0\u9ebc\u662f LENGTH \u51fd\u6578\uff1f<\/h2>\n<p>LENGTH \u51fd\u6578\u662f OceanBase \u4e2d\u7684\u4e00\u500b\u5b57\u7b26\u4e32\u51fd\u6578\uff0c\u7528\u65bc\u8a08\u7b97\u5b57\u7b26\u4e32\u7684\u5b57\u5143\u6578\u3002\u9019\u500b\u51fd\u6578\u5c0d\u65bc\u8655\u7406\u6587\u672c\u6578\u64da\u6642\u975e\u5e38\u6709\u7528\uff0c\u7279\u5225\u662f\u5728\u9700\u8981\u9a57\u8b49\u6216\u5206\u6790\u5b57\u7b26\u4e32\u9577\u5ea6\u7684\u60c5\u6cc1\u4e0b\u3002<\/p>\n<h2 id=\"%e8%aa%9e%e6%b3%95-ieMCLqKARp\">\u8a9e\u6cd5<\/h2>\n<pre><code>\nLENGTH(string)\n<\/code><\/pre>\n<p>\u5728\u9019\u88e1\uff0c<code>string<\/code> \u662f\u8981\u8a08\u7b97\u9577\u5ea6\u7684\u5b57\u7b26\u4e32\u3002\u8a72\u51fd\u6578\u8fd4\u56de\u4e00\u500b\u6574\u6578\uff0c\u8868\u793a\u5b57\u7b26\u4e32\u4e2d\u7684\u5b57\u5143\u6578\u3002<\/p>\n<h2 id=\"%e4%bd%bf%e7%94%a8%e7%a4%ba%e4%be%8b-ieMCLqKARp\">\u4f7f\u7528\u793a\u4f8b<\/h2>\n<p>\u4ee5\u4e0b\u662f\u4e00\u4e9b\u4f7f\u7528 LENGTH \u51fd\u6578\u7684\u793a\u4f8b\uff1a<\/p>\n<h3 id=\"%e7%a4%ba%e4%be%8b-1%ef%bc%9a%e5%9f%ba%e6%9c%ac%e7%94%a8%e6%b3%95-ieMCLqKARp\">\u793a\u4f8b 1\uff1a\u57fa\u672c\u7528\u6cd5<\/h3>\n<pre><code>\nSELECT LENGTH('Hello, World!') AS length_of_string;\n<\/code><\/pre>\n<p>\u9019\u500b\u67e5\u8a62\u5c07\u8fd4\u56de\u5b57\u7b26\u4e32 &#8220;Hello, World!&#8221; \u7684\u9577\u5ea6\uff0c\u7d50\u679c\u70ba 13\u3002<\/p>\n<h3 id=\"%e7%a4%ba%e4%be%8b-2%ef%bc%9a%e8%a8%88%e7%ae%97%e8%a1%a8%e4%b8%ad%e5%ad%97%e6%ae%b5%e7%9a%84%e9%95%b7%e5%ba%a6-ieMCLqKARp\">\u793a\u4f8b 2\uff1a\u8a08\u7b97\u8868\u4e2d\u5b57\u6bb5\u7684\u9577\u5ea6<\/h3>\n<p>\u5047\u8a2d\u6211\u5011\u6709\u4e00\u500b\u540d\u70ba <code>users<\/code> \u7684\u8868\uff0c\u8a72\u8868\u5305\u542b\u4e00\u500b <code>username<\/code> \u5b57\u6bb5\uff0c\u6211\u5011\u53ef\u4ee5\u4f7f\u7528 LENGTH \u51fd\u6578\u4f86\u8a08\u7b97\u6bcf\u500b\u7528\u6236\u540d\u7684\u9577\u5ea6\uff1a<\/p>\n<pre><code>\nSELECT username, LENGTH(username) AS username_length\nFROM users;\n<\/code><\/pre>\n<p>\u9019\u5c07\u8fd4\u56de\u6bcf\u500b\u7528\u6236\u540d\u53ca\u5176\u5c0d\u61c9\u7684\u9577\u5ea6\u3002<\/p>\n<h3 id=\"%e7%a4%ba%e4%be%8b-3%ef%bc%9a%e9%81%8e%e6%bf%be%e9%95%b7%e5%ba%a6-ieMCLqKARp\">\u793a\u4f8b 3\uff1a\u904e\u6ffe\u9577\u5ea6<\/h3>\n<p>\u6211\u5011\u9084\u53ef\u4ee5\u4f7f\u7528 LENGTH \u51fd\u6578\u4f86\u904e\u6ffe\u51fa\u7279\u5b9a\u9577\u5ea6\u7684\u5b57\u7b26\u4e32\u3002\u4f8b\u5982\uff0c\u67e5\u8a62\u6240\u6709\u7528\u6236\u540d\u9577\u5ea6\u5927\u65bc 5 \u7684\u7528\u6236\uff1a<\/p>\n<pre><code>\nSELECT username\nFROM users\nWHERE LENGTH(username) &gt; 5;\n<\/code><\/pre>\n<h2 id=\"%e6%b3%a8%e6%84%8f%e4%ba%8b%e9%a0%85-ieMCLqKARp\">\u6ce8\u610f\u4e8b\u9805<\/h2>\n<ul>\n<li>\u5728\u8a08\u7b97\u5b57\u7b26\u4e32\u9577\u5ea6\u6642\uff0cLENGTH \u51fd\u6578\u8a08\u7b97\u7684\u662f\u5b57\u5143\u6578\uff0c\u800c\u4e0d\u662f\u5b57\u7bc0\u6578\u3002\u9019\u610f\u5473\u8457\u5c0d\u65bc\u67d0\u4e9b\u591a\u5b57\u7bc0\u5b57\u7b26\uff08\u5982\u4e2d\u6587\u5b57\u7b26\uff09\uff0cLENGTH \u51fd\u6578\u7684\u8fd4\u56de\u503c\u53ef\u80fd\u6703\u5c0f\u65bc\u5b57\u7bc0\u6578\u3002<\/li>\n<li>\u5728\u4f7f\u7528 LENGTH \u51fd\u6578\u6642\uff0c\u8acb\u78ba\u4fdd\u5b57\u7b26\u4e32\u4e0d\u70ba NULL\uff0c\u5426\u5247\u5c07\u8fd4\u56de NULL\u3002<\/li>\n<\/ul>\n<h2 id=\"%e7%b5%90%e8%ab%96-ieMCLqKARp\">\u7d50\u8ad6<\/h2>\n<p>LENGTH \u51fd\u6578\u5728 OceanBase \u4e2d\u662f\u4e00\u500b\u975e\u5e38\u5be6\u7528\u7684\u5de5\u5177\uff0c\u80fd\u5920\u5e6b\u52a9\u958b\u767c\u8005\u548c\u6578\u64da\u5206\u6790\u5e2b\u5feb\u901f\u7372\u53d6\u5b57\u7b26\u4e32\u7684\u9577\u5ea6\u3002\u7121\u8ad6\u662f\u5728\u6578\u64da\u6e05\u7406\u3001\u9a57\u8b49\u9084\u662f\u5206\u6790\u904e\u7a0b\u4e2d\uff0c\u9019\u500b\u51fd\u6578\u90fd\u80fd\u63d0\u4f9b\u91cd\u8981\u7684\u652f\u6301\u3002\u901a\u904e\u672c\u6587\u7684\u4ecb\u7d39\u548c\u793a\u4f8b\uff0c\u76f8\u4fe1\u60a8\u5c0d OceanBase \u7684 LENGTH \u51fd\u6578\u6709\u4e86\u66f4\u6df1\u5165\u7684\u4e86\u89e3\u3002<\/p>\n<p>\u5982\u679c\u60a8\u5c0d\u65bc <a href=\"https:\/\/server.hk\">VPS<\/a> \u89e3\u6c7a\u65b9\u6848\u611f\u8208\u8da3\uff0c\u6216\u60f3\u4e86\u89e3\u66f4\u591a\u95dc\u65bc <a href=\"https:\/\/server.hk\">\u9999\u6e2f\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>\u5b66\u4e60OceanBase LENGTH\u7684\u5168\u9762\u6559\u7a0b\uff0c\u638c\u63e1\u9ad8\u6548\u6570\u636e\u5e93\u7ba1\u7406\u4e0e\u4f18\u5316\u6280\u5de7\uff0c\u63d0\u5347\u6570\u636e\u5904\u7406\u80fd\u529b\uff0c\u9002\u5408\u5f00\u53d1\u8005\u4e0e\u6570\u636e\u5e93\u7ba1\u7406\u5458\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-160161","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/160161","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=160161"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/160161\/revisions"}],"predecessor-version":[{"id":160162,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/160161\/revisions\/160162"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=160161"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=160161"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=160161"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}