{"id":168499,"date":"2024-11-06T12:53:17","date_gmt":"2024-11-06T04:53:17","guid":{"rendered":"https:\/\/server.hk\/cnblog\/168499\/"},"modified":"2024-11-06T12:53:18","modified_gmt":"2024-11-06T04:53:18","slug":"sql-%e4%b8%ad-if-%e8%aa%9e%e5%8f%a5%e7%9a%84%e7%94%a8%e6%b3%95%e7%a4%ba%e4%be%8b","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/168499\/","title":{"rendered":"SQL \u4e2d IF \u8a9e\u53e5\u7684\u7528\u6cd5\u793a\u4f8b"},"content":{"rendered":"<h1 id=\"sql-%e4%b8%ad-if-%e8%aa%9e%e5%8f%a5%e7%9a%84%e7%94%a8%e6%b3%95%e7%a4%ba%e4%be%8b-ssnktcbfJq\">SQL \u4e2d IF \u8a9e\u53e5\u7684\u7528\u6cd5\u793a\u4f8b<\/h1>\n<p>\u5728 SQL \u4e2d\uff0cIF \u8a9e\u53e5\u662f\u4e00\u500b\u975e\u5e38\u6709\u7528\u7684\u63a7\u5236\u7d50\u69cb\uff0c\u5141\u8a31\u6839\u64da\u7279\u5b9a\u689d\u4ef6\u57f7\u884c\u4e0d\u540c\u7684\u64cd\u4f5c\u3002\u9019\u7a2e\u8a9e\u53e5\u5728\u6578\u64da\u5eab\u67e5\u8a62\u4e2d\u7d93\u5e38\u88ab\u4f7f\u7528\uff0c\u7279\u5225\u662f\u5728\u9700\u8981\u6839\u64da\u67d0\u4e9b\u689d\u4ef6\u4f86\u6c7a\u5b9a\u8fd4\u56de\u7d50\u679c\u7684\u60c5\u6cc1\u4e0b\u3002\u672c\u6587\u5c07\u63a2\u8a0e SQL \u4e2d IF \u8a9e\u53e5\u7684\u57fa\u672c\u7528\u6cd5\u53ca\u5176\u793a\u4f8b\uff0c\u5e6b\u52a9\u8b80\u8005\u66f4\u597d\u5730\u7406\u89e3\u9019\u4e00\u529f\u80fd\u3002<\/p>\n<h2 id=\"if-%e8%aa%9e%e5%8f%a5%e7%9a%84%e5%9f%ba%e6%9c%ac%e8%aa%9e%e6%b3%95-ssnktcbfJq\">IF \u8a9e\u53e5\u7684\u57fa\u672c\u8a9e\u6cd5<\/h2>\n<p>\u5728 SQL \u4e2d\uff0cIF \u8a9e\u53e5\u7684\u57fa\u672c\u8a9e\u6cd5\u5982\u4e0b\uff1a<\/p>\n<pre><code>\nIF (condition, true_value, false_value)\n<\/code><\/pre>\n<p>\u9019\u88e1\uff0c<code>condition<\/code> \u662f\u4e00\u500b\u5e03\u6797\u8868\u9054\u5f0f\uff0c\u5982\u679c\u70ba\u771f\uff0c\u5247\u8fd4\u56de <code>true_value<\/code>\uff0c\u5426\u5247\u8fd4\u56de <code>false_value<\/code>\u3002<\/p>\n<h2 id=\"%e4%bd%bf%e7%94%a8-if-%e8%aa%9e%e5%8f%a5%e7%9a%84%e5%a0%b4%e6%99%af-ssnktcbfJq\">\u4f7f\u7528 IF \u8a9e\u53e5\u7684\u5834\u666f<\/h2>\n<p>IF \u8a9e\u53e5\u901a\u5e38\u7528\u65bc\u4ee5\u4e0b\u5e7e\u7a2e\u60c5\u6cc1\uff1a<\/p>\n<ul>\n<li>\u6839\u64da\u67d0\u4e9b\u689d\u4ef6\u4f86\u6c7a\u5b9a\u67e5\u8a62\u7d50\u679c\u7684\u986f\u793a\u5167\u5bb9\u3002<\/li>\n<li>\u5728\u66f4\u65b0\u6216\u63d2\u5165\u6578\u64da\u6642\uff0c\u6839\u64da\u689d\u4ef6\u4f86\u6c7a\u5b9a\u8981\u63d2\u5165\u7684\u503c\u3002<\/li>\n<li>\u5728\u5831\u544a\u751f\u6210\u4e2d\uff0c\u6839\u64da\u6578\u64da\u7684\u4e0d\u540c\u72c0\u614b\u4f86\u986f\u793a\u4e0d\u540c\u7684\u8a0a\u606f\u3002<\/li>\n<\/ul>\n<h2 id=\"if-%e8%aa%9e%e5%8f%a5%e7%9a%84%e7%a4%ba%e4%be%8b-ssnktcbfJq\">IF \u8a9e\u53e5\u7684\u793a\u4f8b<\/h2>\n<h3 id=\"%e7%a4%ba%e4%be%8b-1%ef%bc%9a%e5%9f%ba%e6%9c%ac%e7%9a%84-if-%e8%aa%9e%e5%8f%a5-ssnktcbfJq\">\u793a\u4f8b 1\uff1a\u57fa\u672c\u7684 IF \u8a9e\u53e5<\/h3>\n<p>\u5047\u8a2d\u6211\u5011\u6709\u4e00\u500b\u540d\u70ba <code>employees<\/code> \u7684\u8868\uff0c\u5305\u542b\u54e1\u5de5\u7684\u59d3\u540d\u548c\u85aa\u6c34\u3002\u6211\u5011\u5e0c\u671b\u6839\u64da\u85aa\u6c34\u7684\u9ad8\u4f4e\u4f86\u6a19\u8a18\u54e1\u5de5\u7684\u7b49\u7d1a\u3002\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b\u67e5\u8a62\uff1a<\/p>\n<pre><code>\nSELECT name,\n       salary,\n       IF(salary &gt; 50000, '\u9ad8\u7d1a', '\u666e\u901a') AS level\nFROM employees;\n<\/code><\/pre>\n<p>\u5728\u9019\u500b\u67e5\u8a62\u4e2d\uff0c\u6839\u64da\u85aa\u6c34\u7684\u6578\u503c\uff0c\u54e1\u5de5\u5c07\u88ab\u6a19\u8a18\u70ba\u300c\u9ad8\u7d1a\u300d\u6216\u300c\u666e\u901a\u300d\u3002<\/p>\n<h3 id=\"%e7%a4%ba%e4%be%8b-2%ef%bc%9a%e5%9c%a8-update-%e8%aa%9e%e5%8f%a5%e4%b8%ad%e4%bd%bf%e7%94%a8-if-ssnktcbfJq\">\u793a\u4f8b 2\uff1a\u5728 UPDATE \u8a9e\u53e5\u4e2d\u4f7f\u7528 IF<\/h3>\n<p>\u6211\u5011\u4e5f\u53ef\u4ee5\u5728 <code>UPDATE<\/code> \u8a9e\u53e5\u4e2d\u4f7f\u7528 IF \u4f86\u6839\u64da\u689d\u4ef6\u66f4\u65b0\u6578\u64da\u3002\u4f8b\u5982\uff0c\u5047\u8a2d\u6211\u5011\u60f3\u8981\u6839\u64da\u54e1\u5de5\u7684\u85aa\u6c34\u4f86\u8abf\u6574\u4ed6\u5011\u7684\u734e\u91d1\uff1a<\/p>\n<pre><code>\nUPDATE employees\nSET bonus = IF(salary &gt; 50000, 1000, 500);\n<\/code><\/pre>\n<p>\u9019\u689d\u8a9e\u53e5\u5c07\u6839\u64da\u85aa\u6c34\u7684\u9ad8\u4f4e\uff0c\u70ba\u54e1\u5de5\u8a2d\u5b9a\u4e0d\u540c\u7684\u734e\u91d1\u3002<\/p>\n<h3 id=\"%e7%a4%ba%e4%be%8b-3%ef%bc%9a%e5%9c%a8-insert-%e8%aa%9e%e5%8f%a5%e4%b8%ad%e4%bd%bf%e7%94%a8-if-ssnktcbfJq\">\u793a\u4f8b 3\uff1a\u5728 INSERT \u8a9e\u53e5\u4e2d\u4f7f\u7528 IF<\/h3>\n<p>\u5728\u63d2\u5165\u6578\u64da\u6642\uff0c\u6211\u5011\u4e5f\u53ef\u4ee5\u4f7f\u7528 IF \u4f86\u6c7a\u5b9a\u63d2\u5165\u7684\u503c\u3002\u4f8b\u5982\uff0c\u5047\u8a2d\u6211\u5011\u8981\u63d2\u5165\u4e00\u540d\u65b0\u54e1\u5de5\uff0c\u4e26\u6839\u64da\u5176\u85aa\u6c34\u6c7a\u5b9a\u5176\u7b49\u7d1a\uff1a<\/p>\n<pre><code>\nINSERT INTO employees (name, salary, level)\nVALUES ('\u5f35\u4e09', 60000, IF(60000 &gt; 50000, '\u9ad8\u7d1a', '\u666e\u901a'));\n<\/code><\/pre>\n<p>\u9019\u6a23\uff0c\u6211\u5011\u5728\u63d2\u5165\u65b0\u54e1\u5de5\u6642\u5c31\u53ef\u4ee5\u76f4\u63a5\u6c7a\u5b9a\u5176\u7b49\u7d1a\u3002<\/p>\n<h2 id=\"%e7%b8%bd%e7%b5%90-ssnktcbfJq\">\u7e3d\u7d50<\/h2>\n<p>SQL \u4e2d\u7684 IF \u8a9e\u53e5\u662f\u4e00\u500b\u5f37\u5927\u7684\u5de5\u5177\uff0c\u80fd\u5920\u6839\u64da\u689d\u4ef6\u57f7\u884c\u4e0d\u540c\u7684\u64cd\u4f5c\u3002\u7121\u8ad6\u662f\u5728\u67e5\u8a62\u3001\u66f4\u65b0\u9084\u662f\u63d2\u5165\u6578\u64da\u6642\uff0cIF \u8a9e\u53e5\u90fd\u80fd\u63d0\u4f9b\u9748\u6d3b\u6027\u548c\u4fbf\u5229\u6027\u3002\u900f\u904e\u4e0a\u8ff0\u793a\u4f8b\uff0c\u6211\u5011\u53ef\u4ee5\u770b\u5230 IF \u8a9e\u53e5\u5728\u5be6\u969b\u61c9\u7528\u4e2d\u7684\u591a\u6a23\u6027\u548c\u6709\u6548\u6027\u3002<\/p>\n<p>\u5982\u679c\u60a8\u5c0d\u65bc\u6578\u64da\u5eab\u7ba1\u7406\u548c\u64cd\u4f5c\u6709\u66f4\u6df1\u5165\u7684\u9700\u6c42\uff0c\u8003\u616e\u4f7f\u7528 <a href=\"https:\/\/server.hk\">\u9999\u6e2f VPS<\/a> \u670d\u52d9\u4f86\u63d0\u5347\u60a8\u7684\u6578\u64da\u8655\u7406\u80fd\u529b\u3002\u7121\u8ad6\u662f\u9700\u8981\u9ad8\u6548\u7684\u6578\u64da\u5b58\u5132\u9084\u662f\u9748\u6d3b\u7684\u8a08\u7b97\u8cc7\u6e90\uff0c<a href=\"https:\/\/server.hk\">\u9999\u6e2f\u4f3a\u670d\u5668<\/a> \u90fd\u80fd\u70ba\u60a8\u63d0\u4f9b\u7406\u60f3\u7684\u89e3\u6c7a\u65b9\u6848\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4e86\u89e3 SQL \u4e2d IF \u8a9e\u53e5\u7684\u7528\u6cd5\u793a\u4f8b\uff0c\u5b78\u7fd2\u5982\u4f55\u5728\u67e5\u8a62\u4e2d\u6839\u64da\u689d\u4ef6\u8fd4\u56de\u4e0d\u540c\u7684\u7d50\u679c\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-168499","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/168499","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=168499"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/168499\/revisions"}],"predecessor-version":[{"id":168500,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/168499\/revisions\/168500"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=168499"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=168499"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=168499"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}