{"id":144027,"date":"2024-11-01T03:16:30","date_gmt":"2024-10-31T19:16:30","guid":{"rendered":"https:\/\/server.hk\/cnblog\/144027\/"},"modified":"2024-11-01T03:16:31","modified_gmt":"2024-10-31T19:16:31","slug":"sql-%e6%95%b8%e6%93%9a%e5%ba%ab%e5%a6%82%e4%bd%95%e5%af%a6%e7%8f%be%e5%85%a9%e5%80%8b%e5%ad%97%e6%ae%b5%e7%9b%b8%e4%b9%98%e8%a8%88%e7%ae%97-sql-%e6%95%b8%e6%93%9a%e5%ba%ab%e5%85%a9%e5%80%8b%e5%ad%97","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/144027\/","title":{"rendered":"SQL \u6578\u64da\u5eab\u5982\u4f55\u5be6\u73fe\u5169\u500b\u5b57\u6bb5\u76f8\u4e58\u8a08\u7b97 (sql \u6578\u64da\u5eab\u5169\u500b\u5b57\u6bb5\u76f8\u4e58)"},"content":{"rendered":"<h1 id=\"sql-%e6%95%b8%e6%93%9a%e5%ba%ab%e5%a6%82%e4%bd%95%e5%af%a6%e7%8f%be%e5%85%a9%e5%80%8b%e5%ad%97%e6%ae%b5%e7%9b%b8%e4%b9%98%e8%a8%88%e7%ae%97-AZYucyTHWd\">SQL \u6578\u64da\u5eab\u5982\u4f55\u5be6\u73fe\u5169\u500b\u5b57\u6bb5\u76f8\u4e58\u8a08\u7b97<\/h1>\n<p>\u5728\u6578\u64da\u5eab\u7ba1\u7406\u4e2d\uff0cSQL\uff08\u7d50\u69cb\u5316\u67e5\u8a62\u8a9e\u8a00\uff09\u662f\u4e00\u7a2e\u5ee3\u6cdb\u4f7f\u7528\u7684\u8a9e\u8a00\uff0c\u80fd\u5920\u6709\u6548\u5730\u9032\u884c\u6578\u64da\u67e5\u8a62\u548c\u64cd\u4f5c\u3002\u7576\u6211\u5011\u9700\u8981\u5c0d\u6578\u64da\u5eab\u4e2d\u7684\u5169\u500b\u5b57\u6bb5\u9032\u884c\u76f8\u4e58\u8a08\u7b97\u6642\uff0cSQL \u63d0\u4f9b\u4e86\u7c21\u55ae\u800c\u5f37\u5927\u7684\u65b9\u6cd5\u4f86\u5be6\u73fe\u9019\u4e00\u529f\u80fd\u3002\u672c\u6587\u5c07\u63a2\u8a0e\u5982\u4f55\u5728 SQL \u6578\u64da\u5eab\u4e2d\u5be6\u73fe\u5169\u500b\u5b57\u6bb5\u7684\u76f8\u4e58\u8a08\u7b97\uff0c\u4e26\u63d0\u4f9b\u76f8\u95dc\u7684\u793a\u4f8b\u548c\u4ee3\u78bc\u7247\u6bb5\u3002<\/p>\n<h2 id=\"%e5%9f%ba%e6%9c%ac%e6%a6%82%e5%bf%b5-AZYucyTHWd\">\u57fa\u672c\u6982\u5ff5<\/h2>\n<p>\u5728 SQL \u4e2d\uff0c\u5b57\u6bb5\u662f\u8868\u4e2d\u7684\u5217\uff0c\u6bcf\u500b\u5b57\u6bb5\u90fd\u53ef\u4ee5\u5b58\u5132\u7279\u5b9a\u985e\u578b\u7684\u6578\u64da\u3002\u7576\u6211\u5011\u9700\u8981\u8a08\u7b97\u5169\u500b\u5b57\u6bb5\u7684\u4e58\u7a4d\u6642\uff0c\u901a\u5e38\u6703\u4f7f\u7528 SELECT \u8a9e\u53e5\u4f86\u63d0\u53d6\u6578\u64da\u4e26\u9032\u884c\u8a08\u7b97\u3002\u9019\u7a2e\u64cd\u4f5c\u5728\u8a31\u591a\u61c9\u7528\u5834\u666f\u4e2d\u90fd\u975e\u5e38\u5e38\u898b\uff0c\u4f8b\u5982\u8a08\u7b97\u8a02\u55ae\u7e3d\u91d1\u984d\u3001\u7522\u54c1\u50f9\u683c\u548c\u6578\u91cf\u7684\u4e58\u7a4d\u7b49\u3002<\/p>\n<h2 id=\"sql-%e4%b8%ad%e7%9a%84%e4%b9%98%e6%b3%95%e8%a8%88%e7%ae%97-AZYucyTHWd\">SQL \u4e2d\u7684\u4e58\u6cd5\u8a08\u7b97<\/h2>\n<p>\u8981\u5728 SQL \u4e2d\u5be6\u73fe\u5169\u500b\u5b57\u6bb5\u7684\u76f8\u4e58\u8a08\u7b97\uff0c\u6211\u5011\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b\u57fa\u672c\u8a9e\u6cd5\uff1a<\/p>\n<pre><code>SELECT field1 * field2 AS result\nFROM table_name;<\/code><\/pre>\n<p>\u5728\u9019\u88e1\uff0c<code>field1<\/code> \u548c <code>field2<\/code> \u662f\u6211\u5011\u8981\u76f8\u4e58\u7684\u5b57\u6bb5\uff0c<code>result<\/code> \u662f\u8a08\u7b97\u7d50\u679c\u7684\u5225\u540d\uff0c<code>table_name<\/code> \u662f\u5305\u542b\u9019\u4e9b\u5b57\u6bb5\u7684\u8868\u540d\u3002<\/p>\n<h2 id=\"%e7%a4%ba%e4%be%8b-AZYucyTHWd\">\u793a\u4f8b<\/h2>\n<p>\u5047\u8a2d\u6211\u5011\u6709\u4e00\u500b\u540d\u70ba <code>orders<\/code> \u7684\u8868\uff0c\u8a72\u8868\u5305\u542b\u4ee5\u4e0b\u5b57\u6bb5\uff1a<\/p>\n<ul>\n<li><code>product_price<\/code>\uff1a\u7522\u54c1\u50f9\u683c<\/li>\n<li><code>quantity<\/code>\uff1a\u8a02\u8cfc\u6578\u91cf<\/li>\n<\/ul>\n<p>\u6211\u5011\u5e0c\u671b\u8a08\u7b97\u6bcf\u500b\u8a02\u55ae\u7684\u7e3d\u91d1\u984d\uff0c\u5373\u7522\u54c1\u50f9\u683c\u548c\u6578\u91cf\u7684\u4e58\u7a4d\u3002\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b SQL \u67e5\u8a62\uff1a<\/p>\n<pre><code>SELECT product_price, quantity, \n       product_price * quantity AS total_amount\nFROM orders;<\/code><\/pre>\n<p>\u9019\u689d\u67e5\u8a62\u5c07\u8fd4\u56de\u6bcf\u500b\u8a02\u55ae\u7684\u7522\u54c1\u50f9\u683c\u3001\u6578\u91cf\u4ee5\u53ca\u8a08\u7b97\u51fa\u7684\u7e3d\u91d1\u984d\u3002<\/p>\n<h2 id=\"%e9%80%b2%e9%9a%8e%e6%87%89%e7%94%a8-AZYucyTHWd\">\u9032\u968e\u61c9\u7528<\/h2>\n<p>\u9664\u4e86\u57fa\u672c\u7684\u4e58\u6cd5\u8a08\u7b97\u5916\uff0c\u6211\u5011\u9084\u53ef\u4ee5\u5728 SQL \u4e2d\u9032\u884c\u66f4\u8907\u96dc\u7684\u8a08\u7b97\u3002\u4f8b\u5982\uff0c\u5047\u8a2d\u6211\u5011\u5e0c\u671b\u8a08\u7b97\u6bcf\u500b\u8a02\u55ae\u7684\u7e3d\u91d1\u984d\uff0c\u4e26\u4e14\u53ea\u986f\u793a\u7e3d\u91d1\u984d\u5927\u65bc 100 \u7684\u8a02\u55ae\u3002\u6211\u5011\u53ef\u4ee5\u4f7f\u7528 <code>WHERE<\/code> \u5b50\u53e5\u4f86\u904e\u6ffe\u7d50\u679c\uff1a<\/p>\n<pre><code>SELECT product_price, quantity, \n       product_price * quantity AS total_amount\nFROM orders\nWHERE product_price * quantity &gt; 100;<\/code><\/pre>\n<p>\u9019\u6a23\uff0c\u6211\u5011\u5c31\u80fd\u5920\u7372\u5f97\u6240\u6709\u7e3d\u91d1\u984d\u8d85\u904e 100 \u7684\u8a02\u55ae\u3002<\/p>\n<h2 id=\"%e6%b3%a8%e6%84%8f%e4%ba%8b%e9%a0%85-AZYucyTHWd\">\u6ce8\u610f\u4e8b\u9805<\/h2>\n<p>\u5728\u9032\u884c\u5b57\u6bb5\u76f8\u4e58\u8a08\u7b97\u6642\uff0c\u6709\u5e7e\u9ede\u9700\u8981\u6ce8\u610f\uff1a<\/p>\n<ul>\n<li>\u78ba\u4fdd\u5b57\u6bb5\u7684\u6578\u64da\u985e\u578b\u652f\u6301\u6578\u5b78\u904b\u7b97\uff0c\u4f8b\u5982\u6574\u6578\u6216\u6d6e\u9ede\u6578\u3002<\/li>\n<li>\u8655\u7406\u53ef\u80fd\u51fa\u73fe\u7684\u7a7a\u503c\uff08NULL\uff09\uff0c\u4ee5\u907f\u514d\u8a08\u7b97\u932f\u8aa4\u3002\u53ef\u4ee5\u4f7f\u7528 <code>COALESCE<\/code> \u51fd\u6578\u4f86\u8655\u7406\u7a7a\u503c\u3002<\/li>\n<li>\u8003\u616e\u6578\u64da\u7684\u7cbe\u5ea6\uff0c\u7279\u5225\u662f\u5728\u6d89\u53ca\u91d1\u984d\u8a08\u7b97\u6642\uff0c\u61c9\u4f7f\u7528\u9069\u7576\u7684\u6578\u64da\u985e\u578b\u4ee5\u907f\u514d\u7cbe\u5ea6\u640d\u5931\u3002<\/li>\n<\/ul>\n<h2 id=\"%e7%b8%bd%e7%b5%90-AZYucyTHWd\">\u7e3d\u7d50<\/h2>\n<p>\u5728 SQL \u6578\u64da\u5eab\u4e2d\uff0c\u5be6\u73fe\u5169\u500b\u5b57\u6bb5\u76f8\u4e58\u8a08\u7b97\u662f\u4e00\u500b\u7c21\u55ae\u800c\u6709\u6548\u7684\u64cd\u4f5c\u3002\u901a\u904e\u4f7f\u7528\u57fa\u672c\u7684 SELECT \u8a9e\u53e5\u548c\u4e58\u6cd5\u904b\u7b97\u7b26\uff0c\u6211\u5011\u53ef\u4ee5\u8f15\u9b06\u5730\u8a08\u7b97\u51fa\u6240\u9700\u7684\u7d50\u679c\u3002\u7121\u8ad6\u662f\u5728\u65e5\u5e38\u7684\u6578\u64da\u5206\u6790\u9084\u662f\u8907\u96dc\u7684\u5831\u544a\u751f\u6210\u4e2d\uff0c\u9019\u7a2e\u6280\u8853\u90fd\u80fd\u5920\u63d0\u4f9b\u91cd\u8981\u7684\u652f\u6301\u3002\u5982\u679c\u60a8\u9700\u8981\u66f4\u9ad8\u6548\u7684\u6578\u64da\u8655\u7406\u548c\u5b58\u5132\u89e3\u6c7a\u65b9\u6848\uff0c\u8003\u616e\u4f7f\u7528 <a href=\"https:\/\/server.hk\">\u9999\u6e2fVPS<\/a> \u670d\u52d9\uff0c\u4ee5\u4fbf\u66f4\u597d\u5730\u7ba1\u7406\u60a8\u7684\u6578\u64da\u5eab\u548c\u61c9\u7528\u7a0b\u5e8f\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4e86\u89e3\u5982\u4f55\u5728 SQL \u6578\u64da\u5eab\u4e2d\u5be6\u73fe\u5169\u500b\u5b57\u6bb5\u76f8\u4e58\u8a08\u7b97\uff0c\u7c21\u55ae\u6b65\u9a5f\u6559\u4f60\u8f15\u9b06\u9032\u884c\u6578\u64da\u904b\u7b97\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-144027","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/144027","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=144027"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/144027\/revisions"}],"predecessor-version":[{"id":144028,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/144027\/revisions\/144028"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=144027"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=144027"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=144027"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}