{"id":147061,"date":"2022-09-09T07:00:29","date_gmt":"2022-09-08T23:00:29","guid":{"rendered":"http:\/\/www.idc.net\/help\/147061\/"},"modified":"2022-09-09T07:00:29","modified_gmt":"2022-09-08T23:00:29","slug":"%e5%a6%82%e4%bd%95%e6%9b%b4%e6%96%b0%e6%95%b0%e6%8d%ae%e5%ba%93%e4%b8%ad%e7%9a%84%e7%a9%ba%e9%a1%b9%ef%bc%9f-%e6%9b%b4%e6%96%b0%e6%95%b0%e6%8d%ae%e5%ba%93%e4%b8%ad%e4%b8%ba%e7%a9%ba%e5%80%bc%e7%9a%84","status":"publish","type":"post","link":"https:\/\/idc.net\/help\/147061\/","title":{"rendered":"\u5982\u4f55\u66f4\u65b0\u6570\u636e\u5e93\u4e2d\u7684\u7a7a\u9879\uff1f 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* FROM table_name WHERE column_name IS NULL;<\/p>\n<p>\u5728\u8fd9\u4e2a\u8bed\u53e5\u4e2d\uff0ctable_name\u662f\u6211\u4eec\u60f3\u8981\u67e5\u8be2\u7684\u8868\u7684\u540d\u79f0\uff0ccolumn_name\u662f\u6211\u4eec\u60f3\u8981\u68c0\u67e5\u7a7a\u9879\u7684\u5217\u7684\u540d\u79f0\u3002\u8fd9\u4e2a\u8bed\u53e5\u5c06\u68c0\u7d22\u8868\u4e2d\u6240\u6709\u7a7a\u9879\u7684\u884c\u3002<\/p>\n<p>\u66f4\u65b0\u7a7a\u5b57\u7b26\u4e32<\/p>\n<p>\u66f4\u65b0\u7a7a\u5b57\u7b26\u4e32\u662f\u4e00\u4ef6\u76f8\u5bf9\u5bb9\u6613\u7684\u4e8b\u60c5\u3002\u6211\u4eec\u53ea\u9700\u8981\u4f7f\u7528UPDATE\u8bed\u53e5\u5e76\u5c06\u7a7a\u5b57\u7b26\u4e32\u66ff\u6362\u4e3a\u6240\u9700\u7684\u503c\u5373\u53ef\u3002\u4f8b\u5982\uff1a<\/p>\n<p>UPDATE table_name SET column_name=\u2019new_value\u2019 WHERE column_name=\u201d;<\/p>\n<p>\u5728\u8fd9\u4e2a\u8bed\u53e5\u4e2d\uff0ctable_name\u662f\u6211\u4eec\u60f3\u8981\u66f4\u65b0\u7684\u8868\u7684\u540d\u79f0\uff0ccolumn_name\u662f\u6211\u4eec\u60f3\u8981\u66f4\u65b0\u7684\u5217\u7684\u540d\u79f0\uff0cnew_value\u662f\u6211\u4eec\u60f3\u8981\u4f7f\u7528\u7684\u65b0\u503c\u3002WHERE\u5b50\u53e5\u6307\u5b9a\u6211\u4eec\u8981\u66f4\u65b0\u7684\u884c\u3002<\/p>\n<p>\u66f4\u65b0NULL\u503c<\/p>\n<p>\u66f4\u65b0NULL\u503c\u7a0d\u5fae\u590d\u6742\u4e00\u4e9b\u3002\u56e0\u4e3aNULL\u503c\u4e0d\u7b49\u4e8e\u4efb\u4f55\u503c\uff0c\u6240\u4ee5\u6211\u4eec\u4e0d\u80fd\u4f7f\u7528\u76f8\u7b49\u8fd0\u7b97\u7b26=\u6765\u68c0\u6d4bNULL\u503c\u3002\u76f8\u53cd\uff0c\u6211\u4eec\u9700\u8981\u4f7f\u7528IS NULL\u8fd0\u7b97\u7b26\u3002\u4f8b\u5982\uff1a<\/p>\n<p>UPDATE table_name SET column_name=\u2019new_value\u2019 WHERE column_name IS NULL;<\/p>\n<p>\u5728\u8fd9\u4e2a\u8bed\u53e5\u4e2d\uff0ctable_name\u662f\u6211\u4eec\u60f3\u8981\u66f4\u65b0\u7684\u8868\u7684\u540d\u79f0\uff0ccolumn_name\u662f\u6211\u4eec\u60f3\u8981\u66f4\u65b0\u7684\u5217\u7684\u540d\u79f0\uff0cnew_value\u662f\u6211\u4eec\u60f3\u8981\u4f7f\u7528\u7684\u65b0\u503c\u3002WHERE\u5b50\u53e5\u6307\u5b9a\u6211\u4eec\u8981\u66f4\u65b0\u7684\u884c\u3002<\/p>\n<p>\u66f4\u65b0NULL\u503c\u65f6\u8981\u5c0f\u5fc3\u3002\u6211\u4eec\u9700\u8981\u8003\u8651\u5230NULL\u53ef\u80fd\u610f\u5473\u7740\u4e0d\u9002\u7528\u67d0\u4e2a\u5b57\u6bb5\u7684\u503c\uff0c\u56e0\u6b64\u5728\u66f4\u65b0NULL\u503c\u65f6\u9700\u8981\u4ed4\u7ec6\u601d\u8003\u5176\u542b\u4e49\u3002<\/p>\n<p>\u5728\u672c\u6587\u4e2d\uff0c\u6211\u4eec\u4e86\u89e3\u4e86\u4e0d\u540c\u7c7b\u578b\u7684\u7a7a\u9879\uff0c\u5e76\u4ecb\u7ecd\u4e86\u5982\u4f55\u4f7f\u7528SQL\u8bed\u53e5\u6765\u68c0\u67e5\u548c\u66f4\u65b0\u7a7a\u9879\u3002\u5f53\u7a7a\u9879\u5728\u6570\u636e\u5e93\u4e2d\u6210\u4e3a\u4e00\u4e2a\u95ee\u9898\u65f6\uff0c\u8fd9\u4e9b\u6280\u672f\u5c06\u5e2e\u52a9\u6211\u4eec\u5728\u66f4\u65b0\u6570\u636e\u65f6\u66f4\u52a0\u7cbe\u786e\u5730\u5904\u7406\u7a7a\u503c\u3002<\/p>\n<p><strong>\u76f8\u5173\u95ee\u9898\u62d3\u5c55\u9605\u8bfb\uff1a<\/strong><\/p>\n<ul>\n<li>C#\u6570\u636e\u5e93\u7f16\u7a0b\uff0c\u5bf9\u4e8efloat\u7c7b\u578b\u7684\u6570\u636e\u8fdb\u884cupdate\u64cd\u4f5c\uff0c\u4e3a\u4f55\u7a7a\u503c\u66f4\u65b0\u4e86\u4e4b\u540e\u518d\u6b21\u67e5\u627e\u503c\u4e3a0<\/li>\n<\/ul>\n<h3>C#\u6570\u636e\u5e93\u7f16\u7a0b\uff0c\u5bf9\u4e8efloat\u7c7b\u578b\u7684\u6570\u636e\u8fdb\u884cupdate\u64cd\u4f5c\uff0c\u4e3a\u4f55\u7a7a\u503c\u66f4\u65b0\u4e86\u4e4b\u540e\u518d\u6b21\u67e5\u627e\u503c\u4e3a0<\/h3>\n<p>\u4f60\u66f4\u597d\u5728\u66f4\u65b0\u4e4b\u524d\u552f\u8d25\u5224\u65ad\u4e00\u4e0b\uff0c\u53ea\u8ba9\u5c71\u6d1e\u628a\u4e0d\u4e3a\u7a7a\u7684\u5217\u540d\u5199\u5728<\/p>\n<p>update \u8868\u540d set \u4e0d\u4e3a\u7a7a\u7684\u5217\u540d=\u5bf9\u5e94\u5766\u67af\u503c where \u6761\u4ef6<\/p>\n<p>\u8bed\u53e5\u4e2d\uff0c\u5982\u679c\u90a3\u5217\u5141\u8bb8\u7a7a\u81ea\u7136\u5c31\u4e0d\u4f1a\u66f4\u65b0\u3002<\/p>\n<p>\u90a3\u5c31\u529e\u4e0d\u5230\u4e86\u3002\u4e0d\u8fc7\u697c\u4e3b\u53ef\u4ee5\u8bf4\u4e00\u4e0b\u8981\u5b9e\u73b0\u4ec0\u4e48\u9700\u6c42<\/p>\n<p>\u4f60\u767e\u5ea6 c# \u53ef\u7a7a\u6570\u636e\u7c7b\u578b\uff0cfloat\uff1f a=null\uff1b<\/p>\n<p>\u66f4\u65b0\u6570\u636e\u5e93\u4e2d\u4e3a\u7a7a\u503c\u7684\u9879\u7684\u4ecb\u7ecd\u5c31\u804a\u5230\u8fd9\u91cc\u5427\uff0c\u611f\u8c22\u4f60\u82b1\u65f6\u95f4\u9605\u8bfb\u672c\u7ad9\u5185\u5bb9\uff0c\u66f4\u591a\u5173\u4e8e\u66f4\u65b0\u6570\u636e\u5e93\u4e2d\u4e3a\u7a7a\u503c\u7684\u9879,\u5982\u4f55\u66f4\u65b0\u6570\u636e\u5e93\u4e2d\u7684\u7a7a\u9879\uff1f,C#\u6570\u636e\u5e93\u7f16\u7a0b\uff0c\u5bf9\u4e8efloat\u7c7b\u578b\u7684\u6570\u636e\u8fdb\u884cupdate\u64cd\u4f5c\uff0c\u4e3a\u4f55\u7a7a\u503c\u66f4\u65b0\u4e86\u4e4b\u540e\u518d\u6b21\u67e5\u627e\u503c\u4e3a0\u7684\u4fe1\u606f\u522b\u5fd8\u4e86\u5728\u672c\u7ad9\u8fdb\u884c\u67e5\u627e\u5594\u3002<\/p>\n<p><a href=\"http:https:\/\/idc.net\/\">\u9999\u6e2f\u670d\u52a1\u5668<\/a>\u9996\u9009\u540e\u6d6a\u4e91\uff0c2H2G\u9996\u670810\u5143\u5f00\u901a\u3002<br \/>\u540e\u6d6a\u4e91\uff08www.IDC.Net\uff09\u63d0\u4f9b\u7b80\u5355\u597d\u7528\uff0c\u4ef7\u683c\u539a\u9053\u7684\u9999\u6e2f\/\u7f8e\u56fd\u4e91\u670d\u52a1\u5668\u548c\u72ec\u7acb\u670d\u52a1\u5668\u3002IDC+ISP+ICP\u8d44\u8d28\u3002ARIN\u548cAPNIC\u4f1a\u5458\u3002\u6210\u719f\u6280\u672f\u56e2\u961f15\u5e74\u884c\u4e1a\u7ecf\u9a8c\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u5728\u6570\u636e\u5e93\u4e2d\uff0c\u4e00\u4e2a\u7a7a\u9879\u662f\u6307\u4e00\u4e2a\u6ca1\u6709\u4efb\u4f55\u503c\u7684\u5b57\u6bb5\u3002\u8fd9\u53ef\u80fd\u662f\u56e0\u4e3a\u8be5\u5b57\u6bb5\u6ca1\u6709\u88ab\u5b8c\u5168\u586b\u5199\u6216\u6ca1\u6709\u586b\u5199\u4efb\u4f55\u503c\u3002\u5728\u5927\u591a\u6570\u60c5\u51b5\u4e0b [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7038],"tags":[],"class_list":["post-147061","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/idc.net\/help\/wp-json\/wp\/v2\/posts\/147061","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/idc.net\/help\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/idc.net\/help\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/idc.net\/help\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/idc.net\/help\/wp-json\/wp\/v2\/comments?post=147061"}],"version-history":[{"count":0,"href":"https:\/\/idc.net\/help\/wp-json\/wp\/v2\/posts\/147061\/revisions"}],"wp:attachment":[{"href":"https:\/\/idc.net\/help\/wp-json\/wp\/v2\/media?parent=147061"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/idc.net\/help\/wp-json\/wp\/v2\/categories?post=147061"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/idc.net\/help\/wp-json\/wp\/v2\/tags?post=147061"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}