{"id":168375,"date":"2024-11-06T11:51:19","date_gmt":"2024-11-06T03:51:19","guid":{"rendered":"https:\/\/server.hk\/cnblog\/168375\/"},"modified":"2024-11-06T11:51:20","modified_gmt":"2024-11-06T03:51:20","slug":"sql-%e6%95%b8%e6%93%9a%e5%ba%ab%e4%b8%ad%e5%af%a6%e7%8f%be%e7%b2%be%e7%a2%ba%e6%b8%9b%e6%b3%95%e7%9a%84%e5%87%bd%e6%95%b8%e4%bb%8b%e7%b4%b9-sql-%e6%95%b8%e6%93%9a%e5%ba%ab%e9%87%8c%e6%b8%9b%e6%b3%95","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/168375\/","title":{"rendered":"SQL \u6578\u64da\u5eab\u4e2d\u5be6\u73fe\u7cbe\u78ba\u6e1b\u6cd5\u7684\u51fd\u6578\u4ecb\u7d39 (sql \u6578\u64da\u5eab\u91cc\u6e1b\u6cd5\u51fd\u6578)"},"content":{"rendered":"<h1 id=\"sql-%e6%95%b8%e6%93%9a%e5%ba%ab%e4%b8%ad%e5%af%a6%e7%8f%be%e7%b2%be%e7%a2%ba%e6%b8%9b%e6%b3%95%e7%9a%84%e5%87%bd%e6%95%b8%e4%bb%8b%e7%b4%b9-gsacDDcnKD\">SQL \u6578\u64da\u5eab\u4e2d\u5be6\u73fe\u7cbe\u78ba\u6e1b\u6cd5\u7684\u51fd\u6578\u4ecb\u7d39<\/h1>\n<p>\u5728\u6578\u64da\u5eab\u7ba1\u7406\u7cfb\u7d71\u4e2d\uff0c\u6578\u64da\u7684\u6e96\u78ba\u6027\u548c\u5b8c\u6574\u6027\u81f3\u95dc\u91cd\u8981\u3002\u5c24\u5176\u662f\u5728\u9032\u884c\u6578\u5b78\u904b\u7b97\u6642\uff0c\u5982\u4f55\u7cbe\u78ba\u5730\u57f7\u884c\u6e1b\u6cd5\u64cd\u4f5c\u662f\u8a31\u591a\u958b\u767c\u8005\u9700\u8981\u9762\u5c0d\u7684\u6311\u6230\u3002\u672c\u6587\u5c07\u4ecb\u7d39\u5728 SQL \u6578\u64da\u5eab\u4e2d\u5be6\u73fe\u7cbe\u78ba\u6e1b\u6cd5\u7684\u51fd\u6578\u53ca\u5176\u61c9\u7528\u3002<\/p>\n<h2 id=\"1-sql-%e4%b8%ad%e7%9a%84%e5%9f%ba%e6%9c%ac%e6%b8%9b%e6%b3%95%e9%81%8b%e7%ae%97-gsacDDcnKD\">1. SQL \u4e2d\u7684\u57fa\u672c\u6e1b\u6cd5\u904b\u7b97<\/h2>\n<p>\u5728 SQL \u4e2d\uff0c\u6e1b\u6cd5\u904b\u7b97\u53ef\u4ee5\u901a\u904e\u7c21\u55ae\u7684\u7b97\u8853\u904b\u7b97\u7b26\u300c-\u300d\u4f86\u5be6\u73fe\u3002\u9019\u7a2e\u65b9\u5f0f\u9069\u7528\u65bc\u5927\u591a\u6578\u60c5\u6cc1\uff0c\u4f46\u5728\u8655\u7406\u6d6e\u9ede\u6578\u6216\u9ad8\u7cbe\u5ea6\u6578\u64da\u6642\uff0c\u53ef\u80fd\u6703\u51fa\u73fe\u7cbe\u5ea6\u640d\u5931\u7684\u554f\u984c\u3002<\/p>\n<pre><code>SELECT 10.5 - 2.3 AS Result;<\/code><\/pre>\n<p>\u4e0a\u8ff0\u67e5\u8a62\u5c07\u8fd4\u56de 8.2\uff0c\u4f46\u5728\u67d0\u4e9b\u60c5\u6cc1\u4e0b\uff0c\u6d6e\u9ede\u6578\u7684\u8868\u793a\u53ef\u80fd\u5c0e\u81f4\u4e0d\u6e96\u78ba\u7684\u7d50\u679c\u3002<\/p>\n<h2 id=\"2-%e4%bd%bf%e7%94%a8-decimal-%e9%a1%9e%e5%9e%8b%e6%8f%90%e9%ab%98%e7%b2%be%e5%ba%a6-gsacDDcnKD\">2. \u4f7f\u7528 DECIMAL \u985e\u578b\u63d0\u9ad8\u7cbe\u5ea6<\/h2>\n<p>\u70ba\u4e86\u907f\u514d\u6d6e\u9ede\u6578\u904b\u7b97\u4e2d\u7684\u7cbe\u5ea6\u554f\u984c\uff0c\u5efa\u8b70\u4f7f\u7528 <code>DECIMAL<\/code> \u985e\u578b\u4f86\u5b58\u5132\u6578\u64da\u3002<code>DECIMAL<\/code> \u985e\u578b\u5141\u8a31\u7528\u6236\u6307\u5b9a\u6578\u5b57\u7684\u7cbe\u5ea6\u548c\u7bc4\u570d\uff0c\u5f9e\u800c\u78ba\u4fdd\u8a08\u7b97\u7684\u6e96\u78ba\u6027\u3002<\/p>\n<pre><code>CREATE TABLE Transactions (\n    id INT PRIMARY KEY,\n    amount DECIMAL(10, 2)\n);\n\nINSERT INTO Transactions (id, amount) VALUES (1, 10.50), (2, 2.30);\n<\/code><\/pre>\n<p>\u5728\u9019\u500b\u4f8b\u5b50\u4e2d\uff0c\u6211\u5011\u5275\u5efa\u4e86\u4e00\u500b\u540d\u70ba <code>Transactions<\/code> \u7684\u8868\uff0c\u4e26\u4f7f\u7528 <code>DECIMAL(10, 2)<\/code> \u4f86\u78ba\u4fdd\u91d1\u984d\u7684\u7cbe\u78ba\u5ea6\u3002<\/p>\n<h2 id=\"3-%e7%b2%be%e7%a2%ba%e6%b8%9b%e6%b3%95%e7%9a%84%e5%af%a6%e7%8f%be-gsacDDcnKD\">3. \u7cbe\u78ba\u6e1b\u6cd5\u7684\u5be6\u73fe<\/h2>\n<p>\u4f7f\u7528 <code>DECIMAL<\/code> \u985e\u578b\u5f8c\uff0c\u6211\u5011\u53ef\u4ee5\u9032\u884c\u7cbe\u78ba\u7684\u6e1b\u6cd5\u904b\u7b97\u3002\u4ee5\u4e0b\u662f\u5982\u4f55\u5f9e\u4e00\u500b\u91d1\u984d\u4e2d\u6e1b\u53bb\u53e6\u4e00\u500b\u91d1\u984d\u7684\u793a\u4f8b\uff1a<\/p>\n<pre><code>SELECT \n    (SELECT amount FROM Transactions WHERE id = 1) - \n    (SELECT amount FROM Transactions WHERE id = 2) AS Result;\n<\/code><\/pre>\n<p>\u9019\u6bb5\u67e5\u8a62\u5c07\u8fd4\u56de 8.20\uff0c\u9019\u662f\u5169\u500b <code>DECIMAL<\/code> \u6578\u5b57\u4e4b\u9593\u7684\u7cbe\u78ba\u5dee\u503c\u3002<\/p>\n<h2 id=\"4-%e4%bd%bf%e7%94%a8%e5%87%bd%e6%95%b8%e9%80%b2%e8%a1%8c%e6%b8%9b%e6%b3%95%e9%81%8b%e7%ae%97-gsacDDcnKD\">4. \u4f7f\u7528\u51fd\u6578\u9032\u884c\u6e1b\u6cd5\u904b\u7b97<\/h2>\n<p>\u9664\u4e86\u76f4\u63a5\u4f7f\u7528\u7b97\u8853\u904b\u7b97\u7b26\u5916\uff0cSQL \u9084\u63d0\u4f9b\u4e86\u4e00\u4e9b\u5167\u5efa\u51fd\u6578\u4f86\u9032\u884c\u6578\u5b78\u904b\u7b97\u3002\u4f8b\u5982\uff0c<code>SUBTRACT<\/code> \u51fd\u6578\u53ef\u4ee5\u7528\u4f86\u9032\u884c\u6e1b\u6cd5\u904b\u7b97\uff0c\u4f46\u4e26\u4e0d\u662f\u6240\u6709\u7684 SQL \u6578\u64da\u5eab\u90fd\u652f\u6301\u9019\u500b\u51fd\u6578\u3002\u4ee5\u4e0b\u662f\u4f7f\u7528 <code>SUBTRACT<\/code> \u51fd\u6578\u7684\u793a\u4f8b\uff1a<\/p>\n<pre><code>SELECT SUBTRACT(10.5, 2.3) AS Result;<\/code><\/pre>\n<p>\u5982\u679c\u60a8\u7684\u6578\u64da\u5eab\u4e0d\u652f\u6301 <code>SUBTRACT<\/code> \u51fd\u6578\uff0c\u5247\u53ef\u4ee5\u4f7f\u7528\u4e0a\u8ff0\u7684\u7b97\u8853\u904b\u7b97\u7b26\u4f86\u9054\u5230\u76f8\u540c\u7684\u6548\u679c\u3002<\/p>\n<h2 id=\"5-%e6%b3%a8%e6%84%8f%e4%ba%8b%e9%a0%85-gsacDDcnKD\">5. \u6ce8\u610f\u4e8b\u9805<\/h2>\n<ul>\n<li>\u5728\u9032\u884c\u6e1b\u6cd5\u904b\u7b97\u6642\uff0c\u78ba\u4fdd\u6578\u64da\u985e\u578b\u7684\u4e00\u81f4\u6027\uff0c\u4ee5\u907f\u514d\u4e0d\u5fc5\u8981\u7684\u985e\u578b\u8f49\u63db\u3002<\/li>\n<li>\u5c0d\u65bc\u6d89\u53ca\u5927\u91cf\u6578\u64da\u7684\u8a08\u7b97\uff0c\u8003\u616e\u4f7f\u7528\u7d22\u5f15\u4f86\u63d0\u9ad8\u67e5\u8a62\u6027\u80fd\u3002<\/li>\n<li>\u5728\u8a2d\u8a08\u6578\u64da\u5eab\u6642\uff0c\u9078\u64c7\u5408\u9069\u7684\u6578\u64da\u985e\u578b\u4ee5\u78ba\u4fdd\u6578\u64da\u7684\u6e96\u78ba\u6027\u548c\u5b8c\u6574\u6027\u3002<\/li>\n<\/ul>\n<h2 id=\"%e7%b8%bd%e7%b5%90-gsacDDcnKD\">\u7e3d\u7d50<\/h2>\n<p>\u5728 SQL \u6578\u64da\u5eab\u4e2d\u5be6\u73fe\u7cbe\u78ba\u6e1b\u6cd5\u7684\u95dc\u9375\u5728\u65bc\u9078\u64c7\u5408\u9069\u7684\u6578\u64da\u985e\u578b\u548c\u904b\u7b97\u65b9\u5f0f\u3002\u4f7f\u7528 <code>DECIMAL<\/code> \u985e\u578b\u53ef\u4ee5\u6709\u6548\u907f\u514d\u6d6e\u9ede\u6578\u904b\u7b97\u4e2d\u7684\u7cbe\u5ea6\u554f\u984c\uff0c\u4e26\u78ba\u4fdd\u8a08\u7b97\u7d50\u679c\u7684\u6e96\u78ba\u6027\u3002\u5c0d\u65bc\u9700\u8981\u9032\u884c\u5927\u91cf\u6578\u64da\u8655\u7406\u7684\u61c9\u7528\uff0c\u9078\u64c7\u5408\u9069\u7684\u6578\u64da\u5eab\u89e3\u6c7a\u65b9\u6848\u81f3\u95dc\u91cd\u8981\u3002\u82e5\u60a8\u6b63\u5728\u5c0b\u627e\u9ad8\u6548\u7684 <a href=\"https:\/\/server.hk\">\u9999\u6e2fVPS<\/a> \u670d\u52d9\uff0cServer.HK \u63d0\u4f9b\u591a\u7a2e\u9078\u64c7\u4ee5\u6eff\u8db3\u60a8\u7684\u9700\u6c42\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4e86\u89e3\u5982\u4f55\u5728 SQL \u6578\u64da\u5eab\u4e2d\u5be6\u73fe\u7cbe\u78ba\u6e1b\u6cd5\u7684\u51fd\u6578\uff0c\u63d0\u5347\u6578\u64da\u8655\u7406\u7684\u6e96\u78ba\u6027\u8207\u6548\u7387\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-168375","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/168375","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=168375"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/168375\/revisions"}],"predecessor-version":[{"id":168376,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/168375\/revisions\/168376"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=168375"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=168375"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=168375"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}