{"id":5989,"date":"2024-11-14T11:30:03","date_gmt":"2024-11-14T03:30:03","guid":{"rendered":"https:\/\/fwq.ai\/blog\/5989\/"},"modified":"2024-11-14T11:30:03","modified_gmt":"2024-11-14T03:30:03","slug":"sql-varchar%e4%bb%80%e4%b9%88%e6%84%8f%e6%80%9d","status":"publish","type":"post","link":"https:\/\/fwq.ai\/blog\/5989\/","title":{"rendered":"sql varchar\u4ec0\u4e48\u610f\u601d"},"content":{"rendered":"<blockquote><p>\n  varchar\u662f\u4e00\u79cd\u53ef\u53d8\u957f\u5ea6\u5b57\u7b26\u4e32\u6570\u636e\u7c7b\u578b\uff0c\u7528\u4e8e\u5b58\u50a8\u957f\u5ea6\u4e0d\u56fa\u5b9a\u7684\u5b57\u7b26\u4e32\uff0c\u4ee5\u63d0\u9ad8\u7a7a\u95f4\u6548\u7387\u3002\u4e0echar\u76f8\u6bd4\uff0cvarchar\u5141\u8bb8\u53ef\u53d8\u957f\u5ea6\u5b57\u7b26\u4e32\uff0c\u5728\u7a7a\u95f4\u4e0a\u66f4\u6709\u6548\uff0c\u4f46\u6027\u80fd\u53ef\u80fd\u4e0d\u5982char\u3002\u4f7f\u7528varchar\u65f6\uff0c\u5e94\u8003\u8651\u5b57\u6bb5\u7684\u6700\u5927\u957f\u5ea6\uff0c\u907f\u514d\u8fc7\u957f\u7684\u5b57\u6bb5\uff0c\u5e76\u5bf9\u5b57\u6bb5\u8fdb\u884c\u9002\u5f53\u7684\u7d22\u5f15\u4ee5\u63d0\u9ad8\u67e5\u8be2\u6548\u7387\u3002\n<\/p><\/blockquote>\n<p><img decoding=\"async\" src=\"https:\/\/img.php.cn\/upload\/article\/202406\/12\/2024061204302140642.jpg\" class=\"aligncenter\" title=\"sql varchar\u4ec0\u4e48\u610f\u601d\u63d2\u56fe\" alt=\"sql varchar\u4ec0\u4e48\u610f\u601d\u63d2\u56fe\" \/><\/p>\n<p><strong>VARCHAR\u6570\u636e\u7c7b\u578b<\/strong><\/p>\n<p>VARCHAR\u662fSQL\u4e2d\u7684\u4e00\u79cd\u6570\u636e\u7c7b\u578b\uff0c\u7528\u4e8e\u5b58\u50a8\u53ef\u53d8\u957f\u5ea6\u7684\u5b57\u7b26\u4e32\u3002\u5b83\u5141\u8bb8\u5b58\u50a8\u6700\u591a\u6307\u5b9a\u5b57\u8282\u6570\u7684\u5b57\u7b26\uff0c\u800c\u65e0\u9700\u521b\u5efa\u4e00\u4e2a\u56fa\u5b9a\u957f\u5ea6\u7684\u5b57\u6bb5\u3002VARCHAR\u7684\u957f\u5ea6\u9650\u5236\u7531\u6570\u636e\u5e93\u7ba1\u7406\u7cfb\u7edf\uff08DBMS\uff09\u8bbe\u7f6e\uff0c\u901a\u5e38\u4e3a255\u4e2a\u5b57\u7b26\u3002<\/p>\n<p><strong>\u4e3a\u4ec0\u4e48\u4f7f\u7528VARCHAR\uff1f<\/strong><\/p>\n<p>VARCHAR\u4e3b\u8981\u7528\u4e8e\u5b58\u50a8\u957f\u5ea6\u4e0d\u56fa\u5b9a\u7684\u5b57\u7b26\u4e32\u6570\u636e\uff0c\u4f8b\u5982\uff1a<\/p>\n<ul>\n<li>\u540d\u79f0\uff08\u957f\u5ea6\u53ef\u80fd\u56e0\u4eba\u800c\u5f02\uff09<\/li>\n<li>\u5730\u5740\uff08\u957f\u5ea6\u53ef\u80fd\u4f1a\u968f\u7740\u65f6\u95f4\u800c\u53d8\u5316\uff09<\/li>\n<li>\u63cf\u8ff0\uff08\u957f\u5ea6\u53ef\u80fd\u56e0\u590d\u6742\u6027\u800c\u5f02\uff09<\/li>\n<\/ul>\n<p><strong>VARCHAR\u4e0eCHAR\u7684\u533a\u522b<\/strong><\/p>\n<p>VARCHAR\u4e0eCHAR\u662f\u4e24\u79cd\u76f8\u4f3c\u7684\u5b57\u7b26\u4e32\u6570\u636e\u7c7b\u578b\uff0c\u4f46\u5b83\u4eec\u4e4b\u95f4\u6709\u4e00\u4e9b\u5173\u952e\u533a\u522b\uff1a<\/p>\n<ul>\n<li> <strong>\u957f\u5ea6\uff1a<\/strong>VARCHAR\u5141\u8bb8\u53ef\u53d8\u957f\u5ea6\u5b57\u7b26\u4e32\uff0c\u800cCHAR\u521b\u5efa\u56fa\u5b9a\u957f\u5ea6\u5b57\u6bb5\u3002<\/li>\n<li> <strong>\u7a7a\u95f4\u6548\u7387\uff1a<\/strong>VARCHAR\u5728\u7a7a\u95f4\u4e0a\u66f4\u6709\u6548\uff0c\u56e0\u4e3a\u5b83\u53ea\u5b58\u50a8\u5b57\u7b26\u4e32\u6240\u9700\u7684\u5b9e\u9645\u5b57\u8282\u6570\u3002<\/li>\n<li> <strong>\u6027\u80fd\uff1a<\/strong>\u5bf9\u4e8e\u9891\u7e41\u8bbf\u95ee\u7684\u77ed\u5b57\u7b26\u4e32\uff0cCHAR\u53ef\u80fd\u4f1a\u56e0\u4e3a\u5176\u56fa\u5b9a\u957f\u5ea6\u800c\u5177\u6709\u66f4\u597d\u7684\u6027\u80fd\u3002<\/li>\n<\/ul>\n<p><strong>\u4f7f\u7528VARCHAR\u7684\u6700\u4f73\u5b9e\u8df5<\/strong><\/p>\n<p>\u4f7f\u7528VARCHAR\u65f6\uff0c\u5e94\u8003\u8651\u4ee5\u4e0b\u6700\u4f73\u5b9e\u8df5\uff1a<\/p>\n<ul>\n<li>\u8003\u8651\u6bcf\u4e2a\u5b57\u6bb5\u7684\u6700\u5927\u957f\u5ea6\uff0c\u5e76\u76f8\u5e94\u5730\u8bbe\u7f6eVARCHAR\u957f\u5ea6\u3002<\/li>\n<li>\u907f\u514d\u4f7f\u7528\u8fc7\u957f\u7684VARCHAR\u5b57\u6bb5\uff0c\u56e0\u4e3a\u5b83\u4f1a\u6d6a\u8d39\u7a7a\u95f4\u548c\u5f71\u54cd\u6027\u80fd\u3002<\/li>\n<li>\u5bf9VARCHAR\u5b57\u6bb5\u8fdb\u884c\u9002\u5f53\u7684\u7d22\u5f15\u4ee5\u63d0\u9ad8\u67e5\u8be2\u6548\u7387\u3002<\/li>\n<li>\u9002\u5f53\u4f7f\u7528NULL\u503c\u4ee5\u8868\u793a\u672a\u77e5\u6216\u7f3a\u5c11\u7684\u503c\u3002<\/li>\n<\/ul>\n<p>\u4ee5\u4e0a\u5c31\u662fsql varchar\u4ec0\u4e48\u610f\u601d\u7684\u8be6\u7ec6\u5185\u5bb9\uff0c\u66f4\u591a\u8bf7\u5173\u6ce8\u7c73\u4e91\u7f51\u5176\u5b83\u76f8\u5173\u6587\u7ae0\uff01<\/p>\n","protected":false},"excerpt":{"rendered":"<p>varchar\u662f\u4e00\u79cd\u53ef\u53d8\u957f\u5ea6\u5b57\u7b26\u4e32\u6570\u636e\u7c7b\u578b\uff0c\u7528\u4e8e\u5b58\u50a8\u957f\u5ea6\u4e0d\u56fa\u5b9a\u7684\u5b57\u7b26\u4e32\uff0c\u4ee5\u63d0\u9ad8\u7a7a\u95f4\u6548\u7387\u3002\u4e0echar\u76f8\u6bd4\uff0cvarchar\u5141\u8bb8\u53ef\u53d8\u957f\u5ea6\u5b57\u7b26\u4e32\uff0c\u5728\u7a7a\u95f4\u4e0a\u66f4\u6709\u6548\uff0c\u4f46\u6027\u80fd\u53ef\u80fd\u4e0d\u5982char\u3002\u4f7f\u7528varchar\u65f6\uff0c\u5e94\u8003\u8651\u5b57\u6bb5\u7684\u6700\u5927\u957f\u5ea6\uff0c\u907f\u514d\u8fc7\u957f\u7684\u5b57\u6bb5\uff0c\u5e76\u5bf9\u5b57\u6bb5\u8fdb\u884c\u9002\u5f53\u7684\u7d22\u5f15\u4ee5\u63d0\u9ad8\u67e5\u8be2\u6548\u7387\u3002 VARCHAR\u6570\u636e\u7c7b\u578b VARCHAR\u662fSQL\u4e2d\u7684\u4e00\u79cd\u6570\u636e\u7c7b\u578b\uff0c\u7528\u4e8e\u5b58\u50a8\u53ef\u53d8\u957f\u5ea6\u7684\u5b57\u7b26\u4e32\u3002\u5b83\u5141\u8bb8\u5b58\u50a8\u6700\u591a\u6307\u5b9a\u5b57\u8282\u6570\u7684\u5b57\u7b26\uff0c\u800c\u65e0\u9700\u521b\u5efa\u4e00\u4e2a\u56fa\u5b9a\u957f\u5ea6\u7684\u5b57\u6bb5\u3002VARCHAR\u7684\u957f\u5ea6\u9650\u5236\u7531\u6570\u636e\u5e93\u7ba1\u7406\u7cfb\u7edf\uff08DBMS\uff09\u8bbe\u7f6e\uff0c\u901a\u5e38\u4e3a255\u4e2a\u5b57\u7b26\u3002 \u4e3a\u4ec0\u4e48\u4f7f\u7528VARCHAR\uff1f VARCHAR\u4e3b\u8981\u7528\u4e8e\u5b58\u50a8\u957f\u5ea6\u4e0d\u56fa\u5b9a\u7684\u5b57\u7b26\u4e32\u6570\u636e\uff0c\u4f8b\u5982\uff1a \u540d\u79f0\uff08\u957f\u5ea6\u53ef\u80fd\u56e0\u4eba\u800c\u5f02\uff09 \u5730\u5740\uff08\u957f\u5ea6\u53ef\u80fd\u4f1a\u968f\u7740\u65f6\u95f4\u800c\u53d8\u5316\uff09 \u63cf\u8ff0\uff08\u957f\u5ea6\u53ef\u80fd\u56e0\u590d\u6742\u6027\u800c\u5f02\uff09 VARCHAR\u4e0eCHAR\u7684\u533a\u522b VARCHAR\u4e0eCHAR\u662f\u4e24\u79cd\u76f8\u4f3c\u7684\u5b57\u7b26\u4e32\u6570\u636e\u7c7b\u578b\uff0c\u4f46\u5b83\u4eec\u4e4b\u95f4\u6709\u4e00\u4e9b\u5173\u952e\u533a\u522b\uff1a \u957f\u5ea6\uff1aVARCHAR\u5141\u8bb8\u53ef\u53d8\u957f\u5ea6\u5b57\u7b26\u4e32\uff0c\u800cCHAR\u521b\u5efa\u56fa\u5b9a\u957f\u5ea6\u5b57\u6bb5\u3002 \u7a7a\u95f4\u6548\u7387\uff1aVARCHAR\u5728\u7a7a\u95f4\u4e0a\u66f4\u6709\u6548\uff0c\u56e0\u4e3a\u5b83\u53ea\u5b58\u50a8\u5b57\u7b26\u4e32\u6240\u9700\u7684\u5b9e\u9645\u5b57\u8282\u6570\u3002 \u6027\u80fd\uff1a\u5bf9\u4e8e\u9891\u7e41\u8bbf\u95ee\u7684\u77ed\u5b57\u7b26\u4e32\uff0cCHAR\u53ef\u80fd\u4f1a\u56e0\u4e3a\u5176\u56fa\u5b9a\u957f\u5ea6\u800c\u5177\u6709\u66f4\u597d\u7684\u6027\u80fd\u3002 \u4f7f\u7528VARCHAR\u7684\u6700\u4f73\u5b9e\u8df5 \u4f7f\u7528VARCHAR\u65f6\uff0c\u5e94\u8003\u8651\u4ee5\u4e0b\u6700\u4f73\u5b9e\u8df5\uff1a \u8003\u8651\u6bcf\u4e2a\u5b57\u6bb5\u7684\u6700\u5927\u957f\u5ea6\uff0c\u5e76\u76f8\u5e94\u5730\u8bbe\u7f6eVARCHAR\u957f\u5ea6\u3002 \u907f\u514d\u4f7f\u7528\u8fc7\u957f\u7684VARCHAR\u5b57\u6bb5\uff0c\u56e0\u4e3a\u5b83\u4f1a\u6d6a\u8d39\u7a7a\u95f4\u548c\u5f71\u54cd\u6027\u80fd\u3002 \u5bf9VARCHAR\u5b57\u6bb5\u8fdb\u884c\u9002\u5f53\u7684\u7d22\u5f15\u4ee5\u63d0\u9ad8\u67e5\u8be2\u6548\u7387\u3002 \u9002\u5f53\u4f7f\u7528NULL\u503c\u4ee5\u8868\u793a\u672a\u77e5\u6216\u7f3a\u5c11\u7684\u503c\u3002 \u4ee5\u4e0a\u5c31\u662fsql varchar\u4ec0\u4e48\u610f\u601d\u7684\u8be6\u7ec6\u5185\u5bb9\uff0c\u66f4\u591a\u8bf7\u5173\u6ce8\u7c73\u4e91\u7f51\u5176\u5b83\u76f8\u5173\u6587\u7ae0\uff01<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[16],"tags":[],"class_list":["post-5989","post","type-post","status-publish","format-standard","hentry","category-16"],"_links":{"self":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts\/5989","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/comments?post=5989"}],"version-history":[{"count":0,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts\/5989\/revisions"}],"wp:attachment":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/media?parent=5989"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/categories?post=5989"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/tags?post=5989"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}