{"id":96414,"date":"2024-10-20T09:13:18","date_gmt":"2024-10-20T01:13:18","guid":{"rendered":"https:\/\/server.hk\/cnblog\/96414\/"},"modified":"2024-10-20T09:13:19","modified_gmt":"2024-10-20T01:13:19","slug":"pg%e6%95%b8%e6%93%9a%e5%ba%ab%e5%ad%97%e7%ac%a6%e6%88%aa%e5%8f%96%e6%8a%80%e5%b7%a7%e5%85%a8%e6%94%bb%e7%95%a5-pg%e6%95%b8%e6%93%9a%e5%ba%ab%e4%b8%ad%e7%9a%84%e5%ad%97%e7%ac%a6%e6%88%aa%e5%8f%96","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/96414\/","title":{"rendered":"PG\u6578\u64da\u5eab\u5b57\u7b26\u622a\u53d6\u6280\u5de7\u5168\u653b\u7565 (pg\u6578\u64da\u5eab\u4e2d\u7684\u5b57\u7b26\u622a\u53d6)"},"content":{"rendered":"<h1 id=\"pg%e6%95%b8%e6%93%9a%e5%ba%ab%e5%ad%97%e7%ac%a6%e6%88%aa%e5%8f%96%e6%8a%80%e5%b7%a7%e5%85%a8%e6%94%bb%e7%95%a5-RqOxdOwevk\">PG\u6578\u64da\u5eab\u5b57\u7b26\u622a\u53d6\u6280\u5de7\u5168\u653b\u7565<\/h1>\n<p>\u5728\u4f7f\u7528PG\u6578\u64da\u5eab\uff08PostgreSQL\uff09\u9032\u884c\u6578\u64da\u8655\u7406\u6642\uff0c\u5b57\u7b26\u622a\u53d6\u662f\u4e00\u9805\u5e38\u898b\u4e14\u91cd\u8981\u7684\u64cd\u4f5c\u3002\u7121\u8ad6\u662f\u5f9e\u5b57\u7b26\u4e32\u4e2d\u63d0\u53d6\u7279\u5b9a\u90e8\u5206\uff0c\u9084\u662f\u9032\u884c\u6578\u64da\u6e05\u7406\uff0c\u638c\u63e1\u5b57\u7b26\u622a\u53d6\u7684\u6280\u5de7\u90fd\u80fd\u63d0\u9ad8\u6578\u64da\u8655\u7406\u7684\u6548\u7387\u3002\u672c\u6587\u5c07\u6df1\u5165\u63a2\u8a0ePG\u6578\u64da\u5eab\u4e2d\u7684\u5b57\u7b26\u622a\u53d6\u65b9\u6cd5\uff0c\u4e26\u63d0\u4f9b\u5be6\u7528\u7684\u793a\u4f8b\u548c\u4ee3\u78bc\u7247\u6bb5\u3002<\/p>\n<h2 id=\"1-%e5%ad%97%e7%ac%a6%e6%88%aa%e5%8f%96%e7%9a%84%e5%9f%ba%e6%9c%ac%e6%a6%82%e5%bf%b5-RqOxdOwevk\">1. \u5b57\u7b26\u622a\u53d6\u7684\u57fa\u672c\u6982\u5ff5<\/h2>\n<p>\u5b57\u7b26\u622a\u53d6\u662f\u6307\u5f9e\u5b57\u7b26\u4e32\u4e2d\u63d0\u53d6\u51fa\u7279\u5b9a\u7684\u5b50\u5b57\u7b26\u4e32\u3002\u5728PG\u6578\u64da\u5eab\u4e2d\uff0c\u9019\u53ef\u4ee5\u901a\u904e\u591a\u7a2e\u51fd\u6578\u4f86\u5be6\u73fe\uff0c\u6700\u5e38\u7528\u7684\u5305\u62ec\uff1a<\/p>\n<ul>\n<li><code>SUBSTRING<\/code><\/li>\n<li><code>LEFT<\/code><\/li>\n<li><code>RIGHT<\/code><\/li>\n<li><code>POSITION<\/code><\/li>\n<\/ul>\n<h2 id=\"2-%e4%bd%bf%e7%94%a8substring%e5%87%bd%e6%95%b8-RqOxdOwevk\">2. \u4f7f\u7528SUBSTRING\u51fd\u6578<\/h2>\n<p><code>SUBSTRING<\/code>\u51fd\u6578\u662fPG\u6578\u64da\u5eab\u4e2d\u6700\u5e38\u7528\u7684\u5b57\u7b26\u622a\u53d6\u51fd\u6578\u3002\u5176\u57fa\u672c\u8a9e\u6cd5\u5982\u4e0b\uff1a<\/p>\n<pre><code>SUBSTRING(string FROM start FOR length)<\/code><\/pre>\n<p>\u5176\u4e2d\uff0c<code>string<\/code>\u662f\u8981\u622a\u53d6\u7684\u5b57\u7b26\u4e32\uff0c<code>start<\/code>\u662f\u958b\u59cb\u4f4d\u7f6e\uff0c<code>length<\/code>\u662f\u8981\u622a\u53d6\u7684\u5b57\u7b26\u6578\u3002<\/p>\n<h3 id=\"%e7%a4%ba%e4%be%8b%ef%bc%9a-RqOxdOwevk\">\u793a\u4f8b\uff1a<\/h3>\n<pre><code>SELECT SUBSTRING('Hello, World!' FROM 1 FOR 5); -- \u7d50\u679c\u70ba 'Hello'<\/code><\/pre>\n<p>\u5728\u9019\u500b\u4f8b\u5b50\u4e2d\uff0c\u6211\u5011\u5f9e\u5b57\u7b26\u4e32\u4e2d\u63d0\u53d6\u4e86\u524d\u4e94\u500b\u5b57\u7b26\u3002<\/p>\n<h2 id=\"3-%e4%bd%bf%e7%94%a8left%e5%92%8cright%e5%87%bd%e6%95%b8-RqOxdOwevk\">3. \u4f7f\u7528LEFT\u548cRIGHT\u51fd\u6578<\/h2>\n<p>\u9664\u4e86<code>SUBSTRING<\/code>\uff0cPG\u6578\u64da\u5eab\u9084\u63d0\u4f9b\u4e86<code>LEFT<\/code>\u548c<code>RIGHT<\/code>\u51fd\u6578\uff0c\u5206\u5225\u7528\u65bc\u5f9e\u5b57\u7b26\u4e32\u7684\u5de6\u5074\u548c\u53f3\u5074\u622a\u53d6\u5b57\u7b26\u3002<\/p>\n<h3 id=\"left%e5%87%bd%e6%95%b8%e7%a4%ba%e4%be%8b%ef%bc%9a-RqOxdOwevk\">LEFT\u51fd\u6578\u793a\u4f8b\uff1a<\/h3>\n<pre><code>SELECT LEFT('Hello, World!', 5); -- \u7d50\u679c\u70ba 'Hello'<\/code><\/pre>\n<h3 id=\"right%e5%87%bd%e6%95%b8%e7%a4%ba%e4%be%8b%ef%bc%9a-RqOxdOwevk\">RIGHT\u51fd\u6578\u793a\u4f8b\uff1a<\/h3>\n<pre><code>SELECT RIGHT('Hello, World!', 6); -- \u7d50\u679c\u70ba 'World!'<\/code><\/pre>\n<p>\u9019\u4e9b\u51fd\u6578\u7684\u4f7f\u7528\u975e\u5e38\u7c21\u55ae\uff0c\u9069\u5408\u5feb\u901f\u63d0\u53d6\u5b57\u7b26\u4e32\u7684\u7279\u5b9a\u90e8\u5206\u3002<\/p>\n<h2 id=\"4-%e4%bd%bf%e7%94%a8position%e5%87%bd%e6%95%b8-RqOxdOwevk\">4. \u4f7f\u7528POSITION\u51fd\u6578<\/h2>\n<p>\u5728\u67d0\u4e9b\u60c5\u6cc1\u4e0b\uff0c\u6211\u5011\u53ef\u80fd\u9700\u8981\u6839\u64da\u7279\u5b9a\u5b57\u7b26\u7684\u4f4d\u7f6e\u4f86\u622a\u53d6\u5b57\u7b26\u4e32\u3002\u9019\u6642\u53ef\u4ee5\u4f7f\u7528<code>POSITION<\/code>\u51fd\u6578\u4f86\u7372\u53d6\u5b57\u7b26\u7684\u4f4d\u7f6e\u3002<\/p>\n<h3 id=\"%e7%a4%ba%e4%be%8b%ef%bc%9a-RqOxdOwevk\">\u793a\u4f8b\uff1a<\/h3>\n<pre><code>SELECT SUBSTRING('Hello, World!' FROM POSITION(',' IN 'Hello, World!') + 1); -- \u7d50\u679c\u70ba ' World!'<\/code><\/pre>\n<p>\u5728\u9019\u500b\u4f8b\u5b50\u4e2d\uff0c\u6211\u5011\u9996\u5148\u627e\u5230\u4e86\u9017\u865f\u7684\u4f4d\u7f6e\uff0c\u7136\u5f8c\u5f9e\u9017\u865f\u5f8c\u9762\u958b\u59cb\u622a\u53d6\u5b57\u7b26\u4e32\u3002<\/p>\n<h2 id=\"5-%e7%b5%90%e5%90%88%e4%bd%bf%e7%94%a8%e5%ad%97%e7%ac%a6%e6%88%aa%e5%8f%96%e5%87%bd%e6%95%b8-RqOxdOwevk\">5. \u7d50\u5408\u4f7f\u7528\u5b57\u7b26\u622a\u53d6\u51fd\u6578<\/h2>\n<p>\u5728\u5be6\u969b\u61c9\u7528\u4e2d\uff0c\u5b57\u7b26\u622a\u53d6\u51fd\u6578\u53ef\u4ee5\u7d50\u5408\u4f7f\u7528\uff0c\u4ee5\u9054\u5230\u66f4\u8907\u96dc\u7684\u9700\u6c42\u3002\u4f8b\u5982\uff0c\u6211\u5011\u53ef\u4ee5\u5148\u4f7f\u7528<code>POSITION<\/code>\u51fd\u6578\u627e\u5230\u67d0\u500b\u5b57\u7b26\u7684\u4f4d\u7f6e\uff0c\u7136\u5f8c\u518d\u7528<code>SUBSTRING<\/code>\u4f86\u63d0\u53d6\u6240\u9700\u7684\u90e8\u5206\u3002<\/p>\n<h3 id=\"%e7%a4%ba%e4%be%8b%ef%bc%9a-RqOxdOwevk\">\u793a\u4f8b\uff1a<\/h3>\n<pre><code>SELECT SUBSTRING('Hello, World!' FROM POSITION(',' IN 'Hello, World!') + 1 FOR 5); -- \u7d50\u679c\u70ba ' Worl'<\/code><\/pre>\n<p>\u9019\u500b\u67e5\u8a62\u5c07\u63d0\u53d6\u9017\u865f\u5f8c\u7684\u4e94\u500b\u5b57\u7b26\u3002<\/p>\n<h2 id=\"6-%e5%b0%8f%e7%b5%90-RqOxdOwevk\">6. \u5c0f\u7d50<\/h2>\n<p>\u638c\u63e1PG\u6578\u64da\u5eab\u4e2d\u7684\u5b57\u7b26\u622a\u53d6\u6280\u5de7\u5c0d\u65bc\u6578\u64da\u8655\u7406\u81f3\u95dc\u91cd\u8981\u3002\u901a\u904e\u4f7f\u7528<code>SUBSTRING<\/code>\u3001<code>LEFT<\/code>\u3001<code>RIGHT<\/code>\u548c<code>POSITION<\/code>\u7b49\u51fd\u6578\uff0c\u60a8\u53ef\u4ee5\u9748\u6d3b\u5730\u5f9e\u5b57\u7b26\u4e32\u4e2d\u63d0\u53d6\u6240\u9700\u7684\u90e8\u5206\uff0c\u5f9e\u800c\u63d0\u9ad8\u6578\u64da\u8655\u7406\u7684\u6548\u7387\u3002<\/p>\n<p>\u5982\u679c\u60a8\u5c0d\u65bc\u5982\u4f55\u5728\u9ad8\u6548\u7684\u74b0\u5883\u4e2d\u904b\u884cPG\u6578\u64da\u5eab\u6709\u8208\u8da3\uff0c\u5efa\u8b70\u8003\u616e\u4f7f\u7528<a href=\"https:\/\/server.hk\">\u9999\u6e2fVPS<\/a>\u670d\u52d9\uff0c\u4ee5\u7372\u5f97\u66f4\u597d\u7684\u6027\u80fd\u548c\u7a69\u5b9a\u6027\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u638c\u63e1PG\u6578\u64da\u5eab\u4e2d\u7684\u5b57\u7b26\u622a\u53d6\u6280\u5de7\uff0c\u63d0\u5347\u6578\u64da\u8655\u7406\u6548\u7387\uff0c\u8f15\u9b06\u61c9\u5c0d\u5404\u7a2e\u5b57\u7b26\u64cd\u4f5c\u9700\u6c42\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-96414","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/96414","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=96414"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/96414\/revisions"}],"predecessor-version":[{"id":96415,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/96414\/revisions\/96415"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=96414"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=96414"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=96414"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}