{"id":138391,"date":"2024-10-31T14:05:22","date_gmt":"2024-10-31T06:05:22","guid":{"rendered":"https:\/\/server.hk\/cnblog\/138391\/"},"modified":"2024-10-31T14:05:22","modified_gmt":"2024-10-31T06:05:22","slug":"sql-server%e8%ae%8a%e9%87%8f%e8%b3%a6%e5%80%bc%e7%9a%84%e6%96%b9%e6%b3%95","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/138391\/","title":{"rendered":"SQL Server\u8b8a\u91cf\u8ce6\u503c\u7684\u65b9\u6cd5"},"content":{"rendered":"<h1 id=\"sql-server%e8%ae%8a%e9%87%8f%e8%b3%a6%e5%80%bc%e7%9a%84%e6%96%b9%e6%b3%95-ZLHJoYzARq\">SQL Server\u8b8a\u91cf\u8ce6\u503c\u7684\u65b9\u6cd5<\/h1>\n<p>\u5728SQL Server\u4e2d\uff0c\u8b8a\u91cf\u662f\u4e00\u7a2e\u7528\u65bc\u5b58\u5132\u6578\u64da\u7684\u5c0d\u8c61\uff0c\u9019\u4e9b\u6578\u64da\u53ef\u4ee5\u5728\u67e5\u8a62\u6216\u7a0b\u5e8f\u4e2d\u9032\u884c\u64cd\u4f5c\u3002\u8b8a\u91cf\u7684\u8ce6\u503c\u662fSQL Server\u7de8\u7a0b\u4e2d\u7684\u4e00\u500b\u57fa\u672c\u64cd\u4f5c\uff0c\u4e86\u89e3\u5982\u4f55\u6b63\u78ba\u5730\u8ce6\u503c\u5c0d\u65bc\u7de8\u5beb\u9ad8\u6548\u7684SQL\u67e5\u8a62\u548c\u5b58\u5132\u904e\u7a0b\u81f3\u95dc\u91cd\u8981\u3002\u672c\u6587\u5c07\u63a2\u8a0eSQL Server\u4e2d\u8b8a\u91cf\u8ce6\u503c\u7684\u5e7e\u7a2e\u5e38\u898b\u65b9\u6cd5\u3002<\/p>\n<h2 id=\"1-%e4%bd%bf%e7%94%a8set%e8%aa%9e%e5%8f%a5%e8%b3%a6%e5%80%bc-ZLHJoYzARq\">1. \u4f7f\u7528SET\u8a9e\u53e5\u8ce6\u503c<\/h2>\n<p>SET\u8a9e\u53e5\u662fSQL Server\u4e2d\u6700\u5e38\u7528\u7684\u8b8a\u91cf\u8ce6\u503c\u65b9\u6cd5\u4e4b\u4e00\u3002\u5b83\u53ef\u4ee5\u7528\u4f86\u5c07\u4e00\u500b\u503c\u8ce6\u7d66\u8b8a\u91cf\u3002\u4ee5\u4e0b\u662f\u4f7f\u7528SET\u8a9e\u53e5\u8ce6\u503c\u7684\u57fa\u672c\u8a9e\u6cd5\uff1a<\/p>\n<pre><code>DECLARE @VariableName DataType;\nSET @VariableName = Value;<\/code><\/pre>\n<p>\u4f8b\u5982\uff0c\u5047\u8a2d\u6211\u5011\u8981\u5275\u5efa\u4e00\u500b\u6574\u6578\u8b8a\u91cf\u4e26\u8ce6\u503c\u70ba10\uff0c\u53ef\u4ee5\u9019\u6a23\u5beb\uff1a<\/p>\n<pre><code>DECLARE @MyInt INT;\nSET @MyInt = 10;<\/code><\/pre>\n<h2 id=\"2-%e4%bd%bf%e7%94%a8select%e8%aa%9e%e5%8f%a5%e8%b3%a6%e5%80%bc-ZLHJoYzARq\">2. \u4f7f\u7528SELECT\u8a9e\u53e5\u8ce6\u503c<\/h2>\n<p>\u9664\u4e86SET\u8a9e\u53e5\uff0cSELECT\u8a9e\u53e5\u4e5f\u53ef\u4ee5\u7528\u4f86\u8ce6\u503c\u3002\u9019\u7a2e\u65b9\u6cd5\u7279\u5225\u9069\u5408\u5f9e\u67e5\u8a62\u7d50\u679c\u4e2d\u8ce6\u503c\u3002\u4ee5\u4e0b\u662f\u4f7f\u7528SELECT\u8a9e\u53e5\u8ce6\u503c\u7684\u57fa\u672c\u8a9e\u6cd5\uff1a<\/p>\n<pre><code>DECLARE @VariableName DataType;\nSELECT @VariableName = ColumnName FROM TableName WHERE Condition;<\/code><\/pre>\n<p>\u4f8b\u5982\uff0c\u5047\u8a2d\u6211\u5011\u6709\u4e00\u500b\u540d\u70baEmployees\u7684\u8868\uff0c\u4e26\u5e0c\u671b\u5c07\u67d0\u500b\u54e1\u5de5\u7684ID\u8ce6\u503c\u7d66\u8b8a\u91cf\uff0c\u53ef\u4ee5\u9019\u6a23\u5beb\uff1a<\/p>\n<pre><code>DECLARE @EmployeeID INT;\nSELECT @EmployeeID = ID FROM Employees WHERE Name = 'John';<\/code><\/pre>\n<h2 id=\"3-%e4%bd%bf%e7%94%a8%e5%a4%9a%e9%87%8d%e8%b3%a6%e5%80%bc-ZLHJoYzARq\">3. \u4f7f\u7528\u591a\u91cd\u8ce6\u503c<\/h2>\n<p>\u5728SQL Server\u4e2d\uff0c\u6211\u5011\u9084\u53ef\u4ee5\u4f7f\u7528SELECT\u8a9e\u53e5\u4e00\u6b21\u6027\u8ce6\u503c\u7d66\u591a\u500b\u8b8a\u91cf\u3002\u9019\u6a23\u53ef\u4ee5\u63d0\u9ad8\u4ee3\u78bc\u7684\u53ef\u8b80\u6027\u548c\u6548\u7387\u3002\u4ee5\u4e0b\u662f\u591a\u91cd\u8ce6\u503c\u7684\u57fa\u672c\u8a9e\u6cd5\uff1a<\/p>\n<pre><code>DECLARE @Var1 DataType1, @Var2 DataType2;\nSELECT @Var1 = Column1, @Var2 = Column2 FROM TableName WHERE Condition;<\/code><\/pre>\n<p>\u4f8b\u5982\uff0c\u5047\u8a2d\u6211\u5011\u8981\u5f9eEmployees\u8868\u4e2d\u540c\u6642\u7372\u53d6\u54e1\u5de5\u7684ID\u548c\u59d3\u540d\uff0c\u53ef\u4ee5\u9019\u6a23\u5beb\uff1a<\/p>\n<pre><code>DECLARE @EmployeeID INT, @EmployeeName NVARCHAR(50);\nSELECT @EmployeeID = ID, @EmployeeName = Name FROM Employees WHERE ID = 1;<\/code><\/pre>\n<h2 id=\"4-%e4%bd%bf%e7%94%a8case%e8%aa%9e%e5%8f%a5%e8%b3%a6%e5%80%bc-ZLHJoYzARq\">4. \u4f7f\u7528CASE\u8a9e\u53e5\u8ce6\u503c<\/h2>\n<p>CASE\u8a9e\u53e5\u53ef\u4ee5\u6839\u64da\u7279\u5b9a\u689d\u4ef6\u4f86\u8ce6\u503c\uff0c\u9019\u5728\u9700\u8981\u6839\u64da\u4e0d\u540c\u60c5\u6cc1\u8a2d\u7f6e\u8b8a\u91cf\u503c\u6642\u975e\u5e38\u6709\u7528\u3002\u4ee5\u4e0b\u662f\u4f7f\u7528CASE\u8a9e\u53e5\u8ce6\u503c\u7684\u57fa\u672c\u8a9e\u6cd5\uff1a<\/p>\n<pre><code>DECLARE @VariableName DataType;\nSET @VariableName = CASE \n                      WHEN Condition1 THEN Value1\n                      WHEN Condition2 THEN Value2\n                      ELSE DefaultValue\n                    END;<\/code><\/pre>\n<p>\u4f8b\u5982\uff0c\u5047\u8a2d\u6211\u5011\u8981\u6839\u64da\u54e1\u5de5\u7684\u8077\u4f4d\u4f86\u8a2d\u7f6e\u85aa\u6c34\u7b49\u7d1a\uff0c\u53ef\u4ee5\u9019\u6a23\u5beb\uff1a<\/p>\n<pre><code>DECLARE @SalaryLevel INT;\nSET @SalaryLevel = CASE \n                     WHEN @EmployeeID = 1 THEN 1\n                     WHEN @EmployeeID = 2 THEN 2\n                     ELSE 3\n                   END;<\/code><\/pre>\n<h2 id=\"5-%e6%b3%a8%e6%84%8f%e4%ba%8b%e9%a0%85-ZLHJoYzARq\">5. \u6ce8\u610f\u4e8b\u9805<\/h2>\n<ul>\n<li>\u5728\u4f7f\u7528SET\u8a9e\u53e5\u8ce6\u503c\u6642\uff0c\u5982\u679c\u8b8a\u91cf\u7684\u8ce6\u503c\u7d50\u679c\u70baNULL\uff0c\u5247\u8b8a\u91cf\u7684\u503c\u5c07\u88ab\u8a2d\u7f6e\u70baNULL\u3002<\/li>\n<li>\u4f7f\u7528SELECT\u8a9e\u53e5\u8ce6\u503c\u6642\uff0c\u5982\u679c\u67e5\u8a62\u8fd4\u56de\u591a\u884c\uff0c\u5247\u8b8a\u91cf\u5c07\u53ea\u7372\u53d6\u7b2c\u4e00\u884c\u7684\u503c\u3002<\/li>\n<li>\u5728\u591a\u91cd\u8ce6\u503c\u4e2d\uff0c\u8b8a\u91cf\u7684\u8ce6\u503c\u9806\u5e8f\u8207\u67e5\u8a62\u7d50\u679c\u7684\u5217\u9806\u5e8f\u76f8\u540c\u3002<\/li>\n<\/ul>\n<h2 id=\"%e7%b8%bd%e7%b5%90-ZLHJoYzARq\">\u7e3d\u7d50<\/h2>\n<p>\u5728SQL Server\u4e2d\uff0c\u8b8a\u91cf\u8ce6\u503c\u662f\u7de8\u5beb\u67e5\u8a62\u548c\u5b58\u5132\u904e\u7a0b\u7684\u91cd\u8981\u7d44\u6210\u90e8\u5206\u3002\u901a\u904e\u4f7f\u7528SET\u3001SELECT\u3001CASE\u7b49\u8a9e\u53e5\uff0c\u6211\u5011\u53ef\u4ee5\u9748\u6d3b\u5730\u70ba\u8b8a\u91cf\u8ce6\u503c\uff0c\u5f9e\u800c\u63d0\u9ad8\u4ee3\u78bc\u7684\u53ef\u8b80\u6027\u548c\u6548\u7387\u3002\u4e86\u89e3\u9019\u4e9b\u8ce6\u503c\u65b9\u6cd5\u5c07\u5e6b\u52a9\u958b\u767c\u8005\u66f4\u597d\u5730\u7ba1\u7406\u6578\u64da\u548c\u908f\u8f2f\u3002<\/p>\n<p>\u5982\u679c\u60a8\u5c0d\u65bc\u66f4\u9ad8\u6548\u7684\u6578\u64da\u7ba1\u7406\u548c\u5b58\u5132\u89e3\u6c7a\u65b9\u6848\u611f\u8208\u8da3\uff0c\u8acb\u8003\u616e\u6211\u5011\u7684<a href=\"https:\/\/server.hk\">\u9999\u6e2fVPS<\/a>\u670d\u52d9\uff0c\u63d0\u4f9b\u7a69\u5b9a\u7684\u6027\u80fd\u548c\u9748\u6d3b\u7684\u914d\u7f6e\u9078\u64c7\uff0c\u6eff\u8db3\u60a8\u7684\u9700\u6c42\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4e86\u89e3SQL Server\u4e2d\u8b8a\u91cf\u8ce6\u503c\u7684\u65b9\u6cd5\uff0c\u5305\u62ecSET\u548cSELECT\u8a9e\u53e5\u7684\u4f7f\u7528\uff0c\u63d0\u5347\u6578\u64da\u8655\u7406\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-138391","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/138391","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=138391"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/138391\/revisions"}],"predecessor-version":[{"id":138392,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/138391\/revisions\/138392"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=138391"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=138391"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=138391"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}