{"id":94362,"date":"2024-10-19T19:08:46","date_gmt":"2024-10-19T11:08:46","guid":{"rendered":"https:\/\/server.hk\/cnblog\/94362\/"},"modified":"2024-10-19T19:08:46","modified_gmt":"2024-10-19T11:08:46","slug":"oracle-substr%e9%81%8b%e8%a1%8c%e6%99%82%e6%9c%83%e9%81%87%e5%88%b0%e5%93%aa%e4%ba%9b%e5%95%8f%e9%a1%8c%ef%bc%9f","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/94362\/","title":{"rendered":"Oracle substr\u904b\u884c\u6642\u6703\u9047\u5230\u54ea\u4e9b\u554f\u984c\uff1f"},"content":{"rendered":"<h1 id=\"oracle-substr%e9%81%8b%e8%a1%8c%e6%99%82%e6%9c%83%e9%81%87%e5%88%b0%e5%93%aa%e4%ba%9b%e5%95%8f%e9%a1%8c%ef%bc%9f-aFqajdYRvn\">Oracle substr\u904b\u884c\u6642\u6703\u9047\u5230\u54ea\u4e9b\u554f\u984c\uff1f<\/h1>\n<p>\u5728\u4f7f\u7528Oracle\u8cc7\u6599\u5eab\u6642\uff0c<code>SUBSTR<\/code>\u51fd\u6578\u662f\u4e00\u500b\u975e\u5e38\u5e38\u898b\u7684\u5b57\u7b26\u4e32\u8655\u7406\u5de5\u5177\u3002\u5b83\u53ef\u4ee5\u7528\u4f86\u63d0\u53d6\u5b57\u7b26\u4e32\u4e2d\u7684\u5b50\u5b57\u7b26\u4e32\uff0c\u5c0d\u65bc\u6578\u64da\u8655\u7406\u548c\u5831\u544a\u751f\u6210\u975e\u5e38\u6709\u7528\u3002\u7136\u800c\uff0c\u5728\u5be6\u969b\u904b\u884c\u4e2d\uff0c\u4f7f\u7528<code>SUBSTR<\/code>\u51fd\u6578\u6642\u53ef\u80fd\u6703\u9047\u5230\u4e00\u4e9b\u554f\u984c\u3002\u672c\u6587\u5c07\u63a2\u8a0e\u9019\u4e9b\u554f\u984c\u53ca\u5176\u89e3\u6c7a\u65b9\u6848\u3002<\/p>\n<h2 id=\"1-%e5%9f%ba%e6%9c%ac%e8%aa%9e%e6%b3%95%e5%95%8f%e9%a1%8c-aFqajdYRvn\">1. \u57fa\u672c\u8a9e\u6cd5\u554f\u984c<\/h2>\n<p>\u9996\u5148\uff0c<code>SUBSTR<\/code>\u51fd\u6578\u7684\u57fa\u672c\u8a9e\u6cd5\u5982\u4e0b\uff1a<\/p>\n<pre><code>SUBSTR(string, start_position, [length])<\/code><\/pre>\n<p>\u5176\u4e2d\uff0c<code>string<\/code>\u662f\u8981\u8655\u7406\u7684\u5b57\u7b26\u4e32\uff0c<code>start_position<\/code>\u662f\u958b\u59cb\u63d0\u53d6\u7684\u8d77\u59cb\u4f4d\u7f6e\uff0c<code>length<\/code>\u662f\u8981\u63d0\u53d6\u7684\u5b57\u7b26\u6578\u3002\u9700\u8981\u6ce8\u610f\u7684\u662f\uff0c<code>start_position<\/code>\u7684\u8a08\u7b97\u662f\u5f9e1\u958b\u59cb\u7684\uff0c\u800c\u4e0d\u662f0\u3002<\/p>\n<h3 id=\"%e5%b8%b8%e8%a6%8b%e8%aa%9e%e6%b3%95%e9%8c%af%e8%aa%a4-aFqajdYRvn\">\u5e38\u898b\u8a9e\u6cd5\u932f\u8aa4<\/h3>\n<ul>\n<li><strong>\u8d77\u59cb\u4f4d\u7f6e\u8d85\u51fa\u7bc4\u570d\uff1a<\/strong>\u5982\u679c<code>start_position<\/code>\u8d85\u904e\u4e86\u5b57\u7b26\u4e32\u7684\u9577\u5ea6\uff0cOracle\u6703\u8fd4\u56de\u7a7a\u5b57\u7b26\u4e32\u3002<\/li>\n<li><strong>\u8ca0\u6578\u8d77\u59cb\u4f4d\u7f6e\uff1a<\/strong>\u4f7f\u7528\u8ca0\u6578\u4f5c\u70ba<code>start_position<\/code>\u6703\u5c0e\u81f4\u932f\u8aa4\uff0c\u56e0\u70baOracle\u4e0d\u652f\u6301\u8ca0\u6578\u7d22\u5f15\u3002<\/li>\n<\/ul>\n<h2 id=\"2-%e5%ad%97%e7%ac%a6%e9%9b%86%e5%92%8c%e7%b7%a8%e7%a2%bc%e5%95%8f%e9%a1%8c-aFqajdYRvn\">2. \u5b57\u7b26\u96c6\u548c\u7de8\u78bc\u554f\u984c<\/h2>\n<p>\u5728\u8655\u7406\u591a\u8a9e\u8a00\u5b57\u7b26\u4e32\u6642\uff0c\u5b57\u7b26\u96c6\u548c\u7de8\u78bc\u53ef\u80fd\u6703\u5c0e\u81f4\u554f\u984c\u3002Oracle\u8cc7\u6599\u5eab\u652f\u6301\u591a\u7a2e\u5b57\u7b26\u96c6\uff0c\u9019\u53ef\u80fd\u6703\u5f71\u97ff<code>SUBSTR<\/code>\u7684\u884c\u70ba\u3002<\/p>\n<h3 id=\"%e5%ad%97%e7%ac%a6%e9%9b%86%e4%b8%8d%e4%b8%80%e8%87%b4-aFqajdYRvn\">\u5b57\u7b26\u96c6\u4e0d\u4e00\u81f4<\/h3>\n<p>\u5982\u679c\u5b57\u7b26\u4e32\u7684\u5b57\u7b26\u96c6\u8207\u8cc7\u6599\u5eab\u7684\u5b57\u7b26\u96c6\u4e0d\u4e00\u81f4\uff0c\u53ef\u80fd\u6703\u5c0e\u81f4\u63d0\u53d6\u7684\u7d50\u679c\u4e0d\u6b63\u78ba\u3002\u4f8b\u5982\uff0c\u4f7f\u7528UTF-8\u7de8\u78bc\u7684\u5b57\u7b26\u4e32\u5728\u4f7f\u7528<code>SUBSTR<\/code>\u6642\uff0c\u53ef\u80fd\u6703\u56e0\u70ba\u5b57\u7b26\u7684\u5b57\u7bc0\u6578\u4e0d\u540c\u800c\u5c0e\u81f4\u63d0\u53d6\u7684\u5b57\u7b26\u6578\u4e0d\u6b63\u78ba\u3002<\/p>\n<h2 id=\"3-%e6%80%a7%e8%83%bd%e5%95%8f%e9%a1%8c-aFqajdYRvn\">3. \u6027\u80fd\u554f\u984c<\/h2>\n<p>\u5728\u8655\u7406\u5927\u91cf\u6578\u64da\u6642\uff0c<code>SUBSTR<\/code>\u51fd\u6578\u7684\u6027\u80fd\u53ef\u80fd\u6703\u6210\u70ba\u74f6\u9838\u3002\u7279\u5225\u662f\u5728\u67e5\u8a62\u4e2d\u983b\u7e41\u4f7f\u7528<code>SUBSTR<\/code>\u6642\uff0c\u53ef\u80fd\u6703\u5f71\u97ff\u67e5\u8a62\u7684\u57f7\u884c\u6548\u7387\u3002<\/p>\n<h3 id=\"%e8%a7%a3%e6%b1%ba%e6%96%b9%e6%a1%88-aFqajdYRvn\">\u89e3\u6c7a\u65b9\u6848<\/h3>\n<ul>\n<li><strong>\u907f\u514d\u5728WHERE\u5b50\u53e5\u4e2d\u4f7f\u7528\uff1a<\/strong>\u5982\u679c\u53ef\u80fd\uff0c\u61c9\u907f\u514d\u5728<code>WHERE<\/code>\u5b50\u53e5\u4e2d\u4f7f\u7528<code>SUBSTR<\/code>\uff0c\u56e0\u70ba\u9019\u6703\u5c0e\u81f4\u5168\u8868\u6383\u63cf\u3002<\/li>\n<li><strong>\u4f7f\u7528\u7d22\u5f15\uff1a<\/strong>\u5982\u679c\u9700\u8981\u983b\u7e41\u63d0\u53d6\u7279\u5b9a\u6a21\u5f0f\u7684\u5b57\u7b26\u4e32\uff0c\u53ef\u4ee5\u8003\u616e\u5275\u5efa\u51fd\u6578\u7d22\u5f15\u4f86\u63d0\u9ad8\u67e5\u8a62\u6027\u80fd\u3002<\/li>\n<\/ul>\n<h2 id=\"4-null%e5%80%bc%e8%99%95%e7%90%86-aFqajdYRvn\">4. NULL\u503c\u8655\u7406<\/h2>\n<p>\u5728\u4f7f\u7528<code>SUBSTR<\/code>\u6642\uff0cNULL\u503c\u7684\u8655\u7406\u4e5f\u662f\u4e00\u500b\u5e38\u898b\u554f\u984c\u3002\u5982\u679c<code>string<\/code>\u53c3\u6578\u70baNULL\uff0c\u5247<code>SUBSTR<\/code>\u7684\u8fd4\u56de\u503c\u4e5f\u5c07\u662fNULL\u3002<\/p>\n<h3 id=\"%e8%a7%a3%e6%b1%ba%e6%96%b9%e6%a1%88-aFqajdYRvn\">\u89e3\u6c7a\u65b9\u6848<\/h3>\n<p>\u5728\u4f7f\u7528<code>SUBSTR<\/code>\u4e4b\u524d\uff0c\u53ef\u4ee5\u4f7f\u7528<code>NVL<\/code>\u51fd\u6578\u4f86\u8655\u7406NULL\u503c\uff0c\u4f8b\u5982\uff1a<\/p>\n<pre><code>NVL(SUBSTR(string, start_position, length), 'default_value')<\/code><\/pre>\n<h2 id=\"5-%e5%85%b6%e4%bb%96%e5%b8%b8%e8%a6%8b%e5%95%8f%e9%a1%8c-aFqajdYRvn\">5. \u5176\u4ed6\u5e38\u898b\u554f\u984c<\/h2>\n<ul>\n<li><strong>\u63d0\u53d6\u7684\u5b57\u7b26\u6578\u4e0d\u8db3\uff1a<\/strong>\u5982\u679c<code>length<\/code>\u53c3\u6578\u5c0f\u65bc\u5be6\u969b\u53ef\u63d0\u53d6\u7684\u5b57\u7b26\u6578\uff0c\u5247\u53ea\u6703\u8fd4\u56de\u6307\u5b9a\u7684\u5b57\u7b26\u6578\u3002<\/li>\n<li><strong>\u4f7f\u7528\u4e0d\u7576\u7684\u6578\u64da\u985e\u578b\uff1a<\/strong>\u78ba\u4fdd<code>string<\/code>\u53c3\u6578\u662f\u6709\u6548\u7684\u5b57\u7b26\u4e32\u985e\u578b\uff0c\u5426\u5247\u6703\u5c0e\u81f4\u932f\u8aa4\u3002<\/li>\n<\/ul>\n<h2 id=\"%e7%b8%bd%e7%b5%90-aFqajdYRvn\">\u7e3d\u7d50<\/h2>\n<p>\u5728\u4f7f\u7528Oracle\u7684<code>SUBSTR<\/code>\u51fd\u6578\u6642\uff0c\u4e86\u89e3\u53ef\u80fd\u9047\u5230\u7684\u554f\u984c\u53ca\u5176\u89e3\u6c7a\u65b9\u6848\u662f\u975e\u5e38\u91cd\u8981\u7684\u3002\u901a\u904e\u6b63\u78ba\u7684\u8a9e\u6cd5\u3001\u5b57\u7b26\u96c6\u8655\u7406\u3001\u6027\u80fd\u512a\u5316\u548cNULL\u503c\u7ba1\u7406\uff0c\u53ef\u4ee5\u6709\u6548\u5730\u907f\u514d\u5e38\u898b\u7684\u932f\u8aa4\u3002\u5c0d\u65bc\u9700\u8981\u9ad8\u6548\u6578\u64da\u8655\u7406\u7684\u7528\u6236\uff0c\u9078\u64c7\u5408\u9069\u7684<code><a href=\"https:\/\/server.hk\">VPS<\/a><\/code>\u6216<code><a href=\"https:\/\/server.hk\">\u9999\u6e2f\u4f3a\u670d\u5668<\/a><\/code>\u89e3\u6c7a\u65b9\u6848\u4e5f\u80fd\u63d0\u5347\u6574\u9ad4\u6027\u80fd\u548c\u7a69\u5b9a\u6027\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u63a2\u7d22Oracle substr\u51fd\u6578\u904b\u884c\u6642\u53ef\u80fd\u9047\u5230\u7684\u5e38\u898b\u554f\u984c\u53ca\u89e3\u6c7a\u65b9\u6848\uff0c\u63d0\u5347\u6578\u64da\u8655\u7406\u6548\u7387\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-94362","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/94362","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=94362"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/94362\/revisions"}],"predecessor-version":[{"id":94363,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/94362\/revisions\/94363"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=94362"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=94362"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=94362"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}