{"id":181662,"date":"2024-11-09T18:57:32","date_gmt":"2024-11-09T10:57:32","guid":{"rendered":"https:\/\/server.hk\/cnblog\/181662\/"},"modified":"2024-11-09T18:57:33","modified_gmt":"2024-11-09T10:57:33","slug":"%e6%b7%b1%e5%85%a5%e6%8e%a2%e7%a9%b6%ef%bc%9a%e6%95%b8%e6%93%9a%e5%ba%ab%e4%b8%adchar%e5%92%8cvarchar%e7%9a%84%e7%95%b0%e5%90%8c%ef%bc%88%e6%95%b8%e6%93%9a%e5%ba%ab%e4%b8%adchar%e5%92%8cvarchar","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/181662\/","title":{"rendered":"\u6df1\u5165\u63a2\u7a76\uff1a\u6578\u64da\u5eab\u4e2dchar\u548cvarchar\u7684\u7570\u540c\uff08\u6578\u64da\u5eab\u4e2dchar\u548cvarchar\u7684\u5340\u5225\uff09"},"content":{"rendered":"<h1 id=\"%e6%b7%b1%e5%85%a5%e6%8e%a2%e7%a9%b6%ef%bc%9a%e6%95%b8%e6%93%9a%e5%ba%ab%e4%b8%adchar%e5%92%8cvarchar%e7%9a%84%e7%95%b0%e5%90%8c-bxoLgLgsHe\">\u6df1\u5165\u63a2\u7a76\uff1a\u6578\u64da\u5eab\u4e2dchar\u548cvarchar\u7684\u7570\u540c<\/h1>\n<p>\u5728\u6578\u64da\u5eab\u8a2d\u8a08\u4e2d\uff0c\u9078\u64c7\u5408\u9069\u7684\u6578\u64da\u985e\u578b\u5c0d\u65bc\u6027\u80fd\u548c\u5b58\u5132\u6548\u7387\u81f3\u95dc\u91cd\u8981\u3002<code>CHAR<\/code>\u548c<code>VARCHAR<\/code>\u662f\u5169\u7a2e\u5e38\u7528\u7684\u5b57\u7b26\u4e32\u6578\u64da\u985e\u578b\uff0c\u5b83\u5011\u5728\u5b58\u5132\u65b9\u5f0f\u3001\u6027\u80fd\u548c\u4f7f\u7528\u5834\u666f\u4e0a\u5b58\u5728\u986f\u8457\u7684\u5dee\u7570\u3002\u672c\u6587\u5c07\u6df1\u5165\u63a2\u8a0e\u9019\u5169\u8005\u7684\u7570\u540c\uff0c\u5e6b\u52a9\u958b\u767c\u8005\u5728\u8a2d\u8a08\u6578\u64da\u5eab\u6642\u505a\u51fa\u660e\u667a\u7684\u9078\u64c7\u3002<\/p>\n<h2 id=\"%e5%9f%ba%e6%9c%ac%e6%a6%82%e5%bf%b5-bxoLgLgsHe\">\u57fa\u672c\u6982\u5ff5<\/h2>\n<p><code>CHAR<\/code>\u548c<code>VARCHAR<\/code>\u90fd\u662f\u7528\u4f86\u5b58\u5132\u5b57\u7b26\u4e32\u7684\u6578\u64da\u985e\u578b\uff0c\u4f46\u5b83\u5011\u7684\u5b58\u5132\u65b9\u5f0f\u6709\u6240\u4e0d\u540c\uff1a<\/p>\n<ul>\n<li><strong>CHAR\uff1a<\/strong>\u662f\u4e00\u7a2e\u56fa\u5b9a\u9577\u5ea6\u7684\u5b57\u7b26\u4e32\u985e\u578b\u3002\u7576\u5b9a\u7fa9\u4e00\u500b<code>CHAR(n)<\/code>\u985e\u578b\u6642\uff0c\u7121\u8ad6\u5be6\u969b\u5b58\u5132\u7684\u5b57\u7b26\u4e32\u9577\u5ea6\u70ba\u4f55\uff0c\u6578\u64da\u5eab\u90fd\u6703\u5206\u914d\u56fa\u5b9a\u7684<code>n<\/code>\u500b\u5b57\u7b26\u7684\u7a7a\u9593\u3002\u5982\u679c\u5b58\u5132\u7684\u5b57\u7b26\u4e32\u5c11\u65bc<code>n<\/code>\u500b\u5b57\u7b26\uff0c\u5247\u6703\u7528\u7a7a\u683c\u586b\u5145\u3002<\/li>\n<li><strong>VARCHAR\uff1a<\/strong>\u662f\u4e00\u7a2e\u53ef\u8b8a\u9577\u5ea6\u7684\u5b57\u7b26\u4e32\u985e\u578b\u3002\u7576\u5b9a\u7fa9\u4e00\u500b<code>VARCHAR(n)<\/code>\u985e\u578b\u6642\uff0c\u6578\u64da\u5eab\u53ea\u6703\u6839\u64da\u5be6\u969b\u5b58\u5132\u7684\u5b57\u7b26\u4e32\u9577\u5ea6\u4f86\u5206\u914d\u7a7a\u9593\uff0c\u6700\u591a\u53ef\u5b58\u5132<code>n<\/code>\u500b\u5b57\u7b26\u3002\u9019\u610f\u5473\u8457\u5982\u679c\u5b58\u5132\u7684\u5b57\u7b26\u4e32\u9577\u5ea6\u5c0f\u65bc<code>n<\/code>\uff0c\u5247\u53ea\u6703\u4f7f\u7528\u5be6\u969b\u9700\u8981\u7684\u7a7a\u9593\u3002<\/li>\n<\/ul>\n<h2 id=\"%e5%ad%98%e5%84%b2%e6%95%88%e7%8e%87-bxoLgLgsHe\">\u5b58\u5132\u6548\u7387<\/h2>\n<p>\u7531\u65bc<code>CHAR<\/code>\u662f\u56fa\u5b9a\u9577\u5ea6\u7684\uff0c\u56e0\u6b64\u5728\u5b58\u5132\u6548\u7387\u4e0a\uff0c\u5c0d\u65bc\u9577\u5ea6\u76f8\u540c\u7684\u5b57\u7b26\u4e32\uff0c<code>CHAR<\/code>\u7684\u6027\u80fd\u6703\u66f4\u597d\u3002\u9019\u662f\u56e0\u70ba\u6578\u64da\u5eab\u5728\u8655\u7406\u56fa\u5b9a\u9577\u5ea6\u7684\u6578\u64da\u6642\uff0c\u53ef\u4ee5\u66f4\u5feb\u5730\u8a08\u7b97\u51fa\u6578\u64da\u7684\u4f4d\u7f6e\uff0c\u5f9e\u800c\u63d0\u9ad8\u67e5\u8a62\u6548\u7387\u3002<\/p>\n<p>\u7136\u800c\uff0c\u5c0d\u65bc\u9577\u5ea6\u4e0d\u4e00\u7684\u5b57\u7b26\u4e32\uff0c<code>VARCHAR<\/code>\u5247\u66f4\u5177\u512a\u52e2\u3002\u7531\u65bc\u5b83\u6839\u64da\u5be6\u969b\u9577\u5ea6\u5206\u914d\u7a7a\u9593\uff0c\u9019\u6a23\u53ef\u4ee5\u7bc0\u7701\u5b58\u5132\u7a7a\u9593\uff0c\u7279\u5225\u662f\u5728\u5b58\u5132\u5927\u91cf\u8b8a\u9577\u5b57\u7b26\u4e32\u7684\u60c5\u6cc1\u4e0b\u3002<\/p>\n<h2 id=\"%e6%80%a7%e8%83%bd%e8%80%83%e9%87%8f-bxoLgLgsHe\">\u6027\u80fd\u8003\u91cf<\/h2>\n<p>\u5728\u6027\u80fd\u65b9\u9762\uff0c<code>CHAR<\/code>\u548c<code>VARCHAR<\/code>\u5404\u6709\u512a\u52a3\u3002<code>CHAR<\/code>\u5728\u8655\u7406\u56fa\u5b9a\u9577\u5ea6\u7684\u5b57\u7b26\u4e32\u6642\uff0c\u67e5\u8a62\u901f\u5ea6\u8f03\u5feb\uff0c\u56e0\u70ba\u6578\u64da\u5eab\u53ef\u4ee5\u76f4\u63a5\u8a08\u7b97\u51fa\u6bcf\u500b\u5b57\u7b26\u4e32\u7684\u5b58\u5132\u4f4d\u7f6e\u3002\u800c<code>VARCHAR<\/code>\u5728\u8655\u7406\u8b8a\u9577\u5b57\u7b26\u4e32\u6642\uff0c\u53ef\u80fd\u6703\u56e0\u70ba\u9700\u8981\u984d\u5916\u7684\u7a7a\u9593\u4f86\u5b58\u5132\u5b57\u7b26\u4e32\u7684\u9577\u5ea6\u800c\u7a0d\u5fae\u964d\u4f4e\u6027\u80fd\u3002<\/p>\n<h2 id=\"%e4%bd%bf%e7%94%a8%e5%a0%b4%e6%99%af-bxoLgLgsHe\">\u4f7f\u7528\u5834\u666f<\/h2>\n<p>\u9078\u64c7<code>CHAR<\/code>\u9084\u662f<code>VARCHAR<\/code>\u61c9\u6839\u64da\u5177\u9ad4\u7684\u4f7f\u7528\u5834\u666f\u4f86\u6c7a\u5b9a\uff1a<\/p>\n<ul>\n<li><strong>\u4f7f\u7528<code>CHAR<\/code>\u7684\u5834\u666f\uff1a<\/strong>\u9069\u5408\u5b58\u5132\u9577\u5ea6\u56fa\u5b9a\u7684\u5b57\u7b26\u4e32\uff0c\u4f8b\u5982\u570b\u5bb6\u4ee3\u78bc\u3001\u6027\u5225\u7b49\u3002<\/li>\n<li><strong>\u4f7f\u7528<code>VARCHAR<\/code>\u7684\u5834\u666f\uff1a<\/strong>\u9069\u5408\u5b58\u5132\u9577\u5ea6\u4e0d\u56fa\u5b9a\u7684\u5b57\u7b26\u4e32\uff0c\u4f8b\u5982\u7528\u6236\u540d\u3001\u96fb\u5b50\u90f5\u4ef6\u5730\u5740\u7b49\u3002<\/li>\n<\/ul>\n<h2 id=\"%e7%a4%ba%e4%be%8b%e4%bb%a3%e7%a2%bc-bxoLgLgsHe\">\u793a\u4f8b\u4ee3\u78bc<\/h2>\n<p>\u4ee5\u4e0b\u662f\u4f7f\u7528<code>CHAR<\/code>\u548c<code>VARCHAR<\/code>\u7684\u793a\u4f8b\uff1a<\/p>\n<pre><code>CREATE TABLE users (\n    id INT PRIMARY KEY,\n    username VARCHAR(50),\n    gender CHAR(1)\n);\n<\/code><\/pre>\n<p>\u5728\u9019\u500b\u4f8b\u5b50\u4e2d\uff0c<code>username<\/code>\u4f7f\u7528<code>VARCHAR<\/code>\u4f86\u5b58\u5132\u7528\u6236\u540d\uff0c\u56e0\u70ba\u7528\u6236\u540d\u7684\u9577\u5ea6\u4e0d\u56fa\u5b9a\uff1b\u800c<code>gender<\/code>\u4f7f\u7528<code>CHAR<\/code>\u4f86\u5b58\u5132\u6027\u5225\uff0c\u56e0\u70ba\u6027\u5225\u7684\u8868\u793a\u662f\u56fa\u5b9a\u7684\uff08\u4f8b\u5982&#8217;M&#8217;\u6216&#8217;F&#8217;\uff09\u3002<\/p>\n<h2 id=\"%e7%b8%bd%e7%b5%90-bxoLgLgsHe\">\u7e3d\u7d50<\/h2>\n<p>\u7e3d\u7684\u4f86\u8aaa\uff0c<code>CHAR<\/code>\u548c<code>VARCHAR<\/code>\u5404\u6709\u5176\u7279\u9ede\u548c\u9069\u7528\u5834\u666f\u3002\u5728\u9078\u64c7\u6642\uff0c\u958b\u767c\u8005\u61c9\u6839\u64da\u6578\u64da\u7684\u7279\u6027\u548c\u61c9\u7528\u9700\u6c42\u4f86\u505a\u51fa\u5408\u7406\u7684\u9078\u64c7\u3002\u4e86\u89e3\u9019\u4e9b\u5dee\u7570\u4e0d\u50c5\u80fd\u63d0\u9ad8\u6578\u64da\u5eab\u7684\u6027\u80fd\uff0c\u9084\u80fd\u6709\u6548\u5730\u5229\u7528\u5b58\u5132\u7a7a\u9593\u3002<\/p>\n<p>\u5982\u679c\u60a8\u6b63\u5728\u5c0b\u627e\u9ad8\u6548\u7684\u6578\u64da\u5eab\u89e3\u6c7a\u65b9\u6848\uff0c\u8003\u616e\u4f7f\u7528<a href=\"https:\/\/server.hk\">\u9999\u6e2fVPS<\/a>\u4f86\u652f\u6301\u60a8\u7684\u61c9\u7528\u7a0b\u5e8f\uff0c\u7121\u8ad6\u662f\u9700\u8981\u7a69\u5b9a\u7684\u6578\u64da\u5b58\u5132\u9084\u662f\u5feb\u901f\u7684\u6578\u64da\u8655\u7406\uff0cServer.HK\u90fd\u80fd\u63d0\u4f9b\u5408\u9069\u7684\u670d\u52d9\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u6df1\u5165\u63a2\u7a76\u6578\u64da\u5eab\u4e2dchar\u548cvarchar\u7684\u7570\u540c\uff0c\u4e86\u89e3\u5b83\u5011\u7684\u7279\u9ede\u3001\u512a\u7f3a\u9ede\u53ca\u9069\u7528\u5834\u666f\uff0c\u52a9\u4f60\u9078\u64c7\u6700\u4f73\u6578\u64da\u985e\u578b\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-181662","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/181662","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=181662"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/181662\/revisions"}],"predecessor-version":[{"id":181663,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/181662\/revisions\/181663"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=181662"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=181662"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=181662"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}