{"id":64420,"date":"2024-10-14T11:24:15","date_gmt":"2024-10-14T03:24:15","guid":{"rendered":"https:\/\/server.hk\/cnblog\/64420\/"},"modified":"2024-10-14T11:24:15","modified_gmt":"2024-10-14T03:24:15","slug":"ms-sql%e4%b8%ad%e7%9a%84%e9%99%a4%e6%b3%95%e9%81%8b%e7%ae%97%ef%bc%9a%e5%af%a6%e8%b8%90%e6%8c%87%e5%8d%97%ef%bc%88mssql%e9%99%a4%e6%b3%95%ef%bc%89","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/64420\/","title":{"rendered":"MS SQL\u4e2d\u7684\u9664\u6cd5\u904b\u7b97\uff1a\u5be6\u8e10\u6307\u5357\uff08mssql\u9664\u6cd5\uff09"},"content":{"rendered":"<h1 id=\"ms-sql%e4%b8%ad%e7%9a%84%e9%99%a4%e6%b3%95%e9%81%8b%e7%ae%97%ef%bc%9a%e5%af%a6%e8%b8%90%e6%8c%87%e5%8d%97%ef%bc%88mssql%e9%99%a4%e6%b3%95%ef%bc%89-DznzXVBrDz\">MS SQL\u4e2d\u7684\u9664\u6cd5\u904b\u7b97\uff1a\u5be6\u8e10\u6307\u5357\uff08mssql\u9664\u6cd5\uff09<\/h1>\n<p>\u5728\u6578\u64da\u5eab\u7ba1\u7406\u7cfb\u7d71\u4e2d\uff0c\u9664\u6cd5\u904b\u7b97\u662f\u4e00\u500b\u57fa\u672c\u800c\u91cd\u8981\u7684\u64cd\u4f5c\u3002\u5c0d\u65bc\u4f7f\u7528Microsoft SQL Server\uff08MS SQL\uff09\u7684\u958b\u767c\u8005\u548c\u6578\u64da\u5206\u6790\u5e2b\u4f86\u8aaa\uff0c\u4e86\u89e3\u5982\u4f55\u6b63\u78ba\u57f7\u884c\u9664\u6cd5\u904b\u7b97\u662f\u81f3\u95dc\u91cd\u8981\u7684\u3002\u672c\u6587\u5c07\u6df1\u5165\u63a2\u8a0eMS SQL\u4e2d\u7684\u9664\u6cd5\u904b\u7b97\uff0c\u5305\u62ec\u5176\u57fa\u672c\u8a9e\u6cd5\u3001\u5e38\u898b\u554f\u984c\u53ca\u6700\u4f73\u5be6\u8e10\u3002<\/p>\n<h2 id=\"%e5%9f%ba%e6%9c%ac%e8%aa%9e%e6%b3%95-DznzXVBrDz\">\u57fa\u672c\u8a9e\u6cd5<\/h2>\n<p>\u5728MS SQL\u4e2d\uff0c\u9664\u6cd5\u904b\u7b97\u53ef\u4ee5\u901a\u904e\u4f7f\u7528\u659c\u6760\uff08\/\uff09\u4f86\u5be6\u73fe\u3002\u57fa\u672c\u7684\u8a9e\u6cd5\u5982\u4e0b\uff1a<\/p>\n<pre><code>SELECT \u6578\u503c1 \/ \u6578\u503c2 AS \u9664\u6cd5\u7d50\u679c\nFROM \u8868\u540d;<\/code><\/pre>\n<p>\u4f8b\u5982\uff0c\u5047\u8a2d\u6211\u5011\u6709\u4e00\u500b\u540d\u70ba\u201cSales\u201d\u7684\u8868\uff0c\u5305\u542b\u201cTotalSales\u201d\u548c\u201cNumberOfSales\u201d\u5169\u500b\u5b57\u6bb5\uff0c\u6211\u5011\u53ef\u4ee5\u8a08\u7b97\u6bcf\u6b21\u92b7\u552e\u7684\u5e73\u5747\u92b7\u552e\u984d\uff1a<\/p>\n<pre><code>SELECT TotalSales \/ NumberOfSales AS AverageSale\nFROM Sales;<\/code><\/pre>\n<h2 id=\"%e6%95%b4%e6%95%b8%e9%99%a4%e6%b3%95%e8%88%87%e6%b5%ae%e9%bb%9e%e6%95%b8%e9%99%a4%e6%b3%95-DznzXVBrDz\">\u6574\u6578\u9664\u6cd5\u8207\u6d6e\u9ede\u6578\u9664\u6cd5<\/h2>\n<p>\u5728\u9032\u884c\u9664\u6cd5\u904b\u7b97\u6642\uff0c\u958b\u767c\u8005\u9700\u8981\u6ce8\u610f\u6574\u6578\u9664\u6cd5\u548c\u6d6e\u9ede\u6578\u9664\u6cd5\u4e4b\u9593\u7684\u5340\u5225\u3002\u7576\u5169\u500b\u6574\u6578\u76f8\u9664\u6642\uff0c\u7d50\u679c\u5c07\u88ab\u622a\u65b7\u70ba\u6574\u6578\u3002\u4f8b\u5982\uff1a<\/p>\n<pre><code>SELECT 5 \/ 2 AS Result; -- \u7d50\u679c\u70ba 2<\/code><\/pre>\n<p>\u70ba\u4e86\u7372\u5f97\u6d6e\u9ede\u6578\u7d50\u679c\uff0c\u53ef\u4ee5\u5c07\u5176\u4e2d\u4e00\u500b\u64cd\u4f5c\u6578\u8f49\u63db\u70ba\u6d6e\u9ede\u6578\u3002\u9019\u53ef\u4ee5\u901a\u904e\u4f7f\u7528CAST\u6216CONVERT\u51fd\u6578\u4f86\u5be6\u73fe\uff1a<\/p>\n<pre><code>SELECT CAST(5 AS FLOAT) \/ 2 AS Result; -- \u7d50\u679c\u70ba 2.5<\/code><\/pre>\n<h2 id=\"%e8%99%95%e7%90%86%e9%99%a4%e4%bb%a5%e9%9b%b6%e7%9a%84%e6%83%85%e6%b3%81-DznzXVBrDz\">\u8655\u7406\u9664\u4ee5\u96f6\u7684\u60c5\u6cc1<\/h2>\n<p>\u5728\u9032\u884c\u9664\u6cd5\u904b\u7b97\u6642\uff0c\u9664\u4ee5\u96f6\u6703\u5c0e\u81f4\u932f\u8aa4\u3002\u70ba\u4e86\u907f\u514d\u9019\u7a2e\u60c5\u6cc1\uff0c\u53ef\u4ee5\u4f7f\u7528CASE\u8a9e\u53e5\u4f86\u6aa2\u67e5\u9664\u6578\u662f\u5426\u70ba\u96f6\uff1a<\/p>\n<pre><code>SELECT \n    CASE \n        WHEN NumberOfSales = 0 THEN '\u7121\u6cd5\u8a08\u7b97'\n        ELSE TotalSales \/ NumberOfSales \n    END AS AverageSale\nFROM Sales;<\/code><\/pre>\n<h2 id=\"%e6%9c%80%e4%bd%b3%e5%af%a6%e8%b8%90-DznzXVBrDz\">\u6700\u4f73\u5be6\u8e10<\/h2>\n<ul>\n<li><strong>\u4f7f\u7528\u6d6e\u9ede\u6578\u904b\u7b97\uff1a<\/strong>\u5728\u9700\u8981\u7cbe\u78ba\u7d50\u679c\u7684\u60c5\u6cc1\u4e0b\uff0c\u76e1\u91cf\u4f7f\u7528\u6d6e\u9ede\u6578\u9032\u884c\u904b\u7b97\u3002<\/li>\n<li><strong>\u6aa2\u67e5\u9664\u6578\uff1a<\/strong>\u59cb\u7d42\u6aa2\u67e5\u9664\u6578\u662f\u5426\u70ba\u96f6\uff0c\u4ee5\u907f\u514d\u904b\u884c\u6642\u932f\u8aa4\u3002<\/li>\n<li><strong>\u4f7f\u7528NULL\u8655\u7406\uff1a<\/strong>\u5728\u67d0\u4e9b\u60c5\u6cc1\u4e0b\uff0c\u9664\u6578\u53ef\u80fd\u70baNULL\uff0c\u9019\u6642\u53ef\u4ee5\u4f7f\u7528COALESCE\u51fd\u6578\u4f86\u63d0\u4f9b\u9ed8\u8a8d\u503c\u3002<\/li>\n<\/ul>\n<h2 id=\"%e5%af%a6%e9%9a%9b%e6%87%89%e7%94%a8%e7%a4%ba%e4%be%8b-DznzXVBrDz\">\u5be6\u969b\u61c9\u7528\u793a\u4f8b<\/h2>\n<p>\u5047\u8a2d\u6211\u5011\u6709\u4e00\u500b\u201cEmployees\u201d\u8868\uff0c\u5305\u542b\u201cSalary\u201d\u548c\u201cBonus\u201d\u5b57\u6bb5\uff0c\u6211\u5011\u5e0c\u671b\u8a08\u7b97\u6bcf\u4f4d\u54e1\u5de5\u7684\u7e3d\u6536\u5165\u3002\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b\u67e5\u8a62\uff1a<\/p>\n<pre><code>SELECT \n    EmployeeID, \n    Salary + COALESCE(Bonus, 0) AS TotalIncome\nFROM Employees;<\/code><\/pre>\n<p>\u5982\u679c\u6211\u5011\u60f3\u8a08\u7b97\u6bcf\u4f4d\u54e1\u5de5\u7684\u6536\u5165\u8207\u5de5\u4f5c\u5e74\u9650\u7684\u6bd4\u7387\uff0c\u53ef\u4ee5\u9019\u6a23\u505a\uff1a<\/p>\n<pre><code>SELECT \n    EmployeeID, \n    TotalIncome \/ YearsOfService AS IncomePerYear\nFROM \n    (SELECT \n        EmployeeID, \n        Salary + COALESCE(Bonus, 0) AS TotalIncome, \n        YearsOfService \n     FROM Employees) AS SubQuery\nWHERE YearsOfService &gt; 0;<\/code><\/pre>\n<h2 id=\"%e7%b8%bd%e7%b5%90-DznzXVBrDz\">\u7e3d\u7d50<\/h2>\n<p>\u5728MS SQL\u4e2d\uff0c\u9664\u6cd5\u904b\u7b97\u662f\u4e00\u500b\u57fa\u672c\u4f46\u91cd\u8981\u7684\u529f\u80fd\u3002\u901a\u904e\u6b63\u78ba\u4f7f\u7528\u8a9e\u6cd5\u3001\u8655\u7406\u6574\u6578\u548c\u6d6e\u9ede\u6578\u7684\u5340\u5225\u3001\u907f\u514d\u9664\u4ee5\u96f6\u7684\u932f\u8aa4\u4ee5\u53ca\u9075\u5faa\u6700\u4f73\u5be6\u8e10\uff0c\u958b\u767c\u8005\u53ef\u4ee5\u6709\u6548\u5730\u9032\u884c\u6578\u64da\u8a08\u7b97\u3002\u5c0d\u65bc\u9700\u8981\u9ad8\u6548\u6578\u64da\u8655\u7406\u7684\u4f01\u696d\uff0c\u9078\u64c7\u5408\u9069\u7684 <a href=\"https:\/\/server.hk\">VPS<\/a> \u89e3\u6c7a\u65b9\u6848\u5c07\u6709\u52a9\u65bc\u63d0\u5347\u6578\u64da\u5eab\u6027\u80fd\u548c\u7a69\u5b9a\u6027\u3002\u4e86\u89e3MS SQL\u7684\u9664\u6cd5\u904b\u7b97\u5c07\u4f7f\u60a8\u5728\u6578\u64da\u5206\u6790\u548c\u5831\u544a\u4e2d\u66f4\u52a0\u5f97\u5fc3\u61c9\u624b\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u63a2\u7d22MS SQL\u4e2d\u7684\u9664\u6cd5\u904b\u7b97\uff0c\u4e86\u89e3mssql\u9664\u6cd5\u7684\u5be6\u8e10\u6307\u5357\uff0c\u63d0\u5347\u6578\u64da\u8655\u7406\u6548\u7387\u8207\u6e96\u78ba\u6027\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-64420","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/64420","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=64420"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/64420\/revisions"}],"predecessor-version":[{"id":64421,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/64420\/revisions\/64421"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=64420"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=64420"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=64420"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}