{"id":152907,"date":"2024-11-02T03:01:21","date_gmt":"2024-11-01T19:01:21","guid":{"rendered":"https:\/\/server.hk\/cnblog\/152907\/"},"modified":"2024-11-02T03:01:22","modified_gmt":"2024-11-01T19:01:22","slug":"%e5%88%9d%e7%b4%9a-sql-select-%e8%aa%9e%e6%b3%95","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/152907\/","title":{"rendered":"\u521d\u7d1a SQL SELECT \u8a9e\u6cd5"},"content":{"rendered":"<h1 id=\"%e5%88%9d%e7%b4%9a-sql-select-%e8%aa%9e%e6%b3%95-cOKTUCfjcf\">\u521d\u7d1a SQL SELECT \u8a9e\u6cd5<\/h1>\n<p>SQL\uff08\u7d50\u69cb\u5316\u67e5\u8a62\u8a9e\u8a00\uff09\u662f\u4e00\u7a2e\u7528\u65bc\u7ba1\u7406\u548c\u64cd\u4f5c\u95dc\u4fc2\u578b\u6578\u64da\u5eab\u7684\u6a19\u6e96\u8a9e\u8a00\u3002\u5728\u6578\u64da\u5eab\u4e2d\uff0c\u6700\u5e38\u7528\u7684\u64cd\u4f5c\u4e4b\u4e00\u5c31\u662f\u67e5\u8a62\u6578\u64da\uff0c\u800c\u9019\u901a\u5e38\u662f\u901a\u904e <code>SELECT<\/code> \u8a9e\u53e5\u4f86\u5be6\u73fe\u7684\u3002\u672c\u6587\u5c07\u4ecb\u7d39\u521d\u7d1a SQL <code>SELECT<\/code> \u8a9e\u6cd5\uff0c\u5e6b\u52a9\u8b80\u8005\u7406\u89e3\u5982\u4f55\u5f9e\u6578\u64da\u5eab\u4e2d\u63d0\u53d6\u6240\u9700\u7684\u4fe1\u606f\u3002<\/p>\n<h2 id=\"%e5%9f%ba%e6%9c%ac%e7%9a%84-select-%e8%aa%9e%e6%b3%95-cOKTUCfjcf\">\u57fa\u672c\u7684 SELECT \u8a9e\u6cd5<\/h2>\n<p>\u6700\u57fa\u672c\u7684 <code>SELECT<\/code> \u8a9e\u6cd5\u5982\u4e0b\uff1a<\/p>\n<pre><code>SELECT column1, column2, ...\nFROM table_name;<\/code><\/pre>\n<p>\u5728\u9019\u88e1\uff0c<code>column1, column2, ...<\/code> \u662f\u4f60\u5e0c\u671b\u67e5\u8a62\u7684\u5217\u540d\uff0c\u800c <code>table_name<\/code> \u662f\u4f60\u8981\u67e5\u8a62\u7684\u6578\u64da\u8868\u540d\u7a31\u3002<\/p>\n<h3 id=\"%e7%af%84%e4%be%8b-cOKTUCfjcf\">\u7bc4\u4f8b<\/h3>\n<p>\u5047\u8a2d\u6211\u5011\u6709\u4e00\u500b\u540d\u70ba <code>employees<\/code> \u7684\u6578\u64da\u8868\uff0c\u5305\u542b\u4ee5\u4e0b\u5217\uff1a<code>id<\/code>\u3001<code>name<\/code>\u3001<code>position<\/code> \u548c <code>salary<\/code>\u3002\u5982\u679c\u6211\u5011\u60f3\u67e5\u8a62\u6240\u6709\u54e1\u5de5\u7684\u59d3\u540d\u548c\u8077\u4f4d\uff0c\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b SQL \u8a9e\u53e5\uff1a<\/p>\n<pre><code>SELECT name, position\nFROM employees;<\/code><\/pre>\n<h2 id=\"%e4%bd%bf%e7%94%a8-%e7%ac%a6%e8%99%9f%e6%9f%a5%e8%a9%a2%e6%89%80%e6%9c%89%e5%88%97-cOKTUCfjcf\">\u4f7f\u7528 * \u7b26\u865f\u67e5\u8a62\u6240\u6709\u5217<\/h2>\n<p>\u5982\u679c\u4f60\u5e0c\u671b\u67e5\u8a62\u6578\u64da\u8868\u4e2d\u7684\u6240\u6709\u5217\uff0c\u53ef\u4ee5\u4f7f\u7528 <code>*<\/code> \u7b26\u865f\u3002\u4ee5\u4e0b\u662f\u67e5\u8a62\u6240\u6709\u54e1\u5de5\u4fe1\u606f\u7684\u7bc4\u4f8b\uff1a<\/p>\n<pre><code>SELECT *\nFROM employees;<\/code><\/pre>\n<h2 id=\"%e6%b7%bb%e5%8a%a0%e6%a2%9d%e4%bb%b6%ef%bc%9awhere-%e5%ad%90%e5%8f%a5-cOKTUCfjcf\">\u6dfb\u52a0\u689d\u4ef6\uff1aWHERE \u5b50\u53e5<\/h2>\n<p>\u5728\u67e5\u8a62\u4e2d\uff0c<code>WHERE<\/code> \u5b50\u53e5\u7528\u65bc\u6307\u5b9a\u67e5\u8a62\u7684\u689d\u4ef6\u3002\u9019\u6a23\u53ef\u4ee5\u904e\u6ffe\u51fa\u7b26\u5408\u7279\u5b9a\u689d\u4ef6\u7684\u6578\u64da\u3002\u4f8b\u5982\uff0c\u5982\u679c\u6211\u5011\u53ea\u60f3\u67e5\u8a62\u8077\u4f4d\u70ba\u300c\u7d93\u7406\u300d\u7684\u54e1\u5de5\uff0c\u53ef\u4ee5\u9019\u6a23\u5beb\uff1a<\/p>\n<pre><code>SELECT name, salary\nFROM employees\nWHERE position = '\u7d93\u7406';<\/code><\/pre>\n<h2 id=\"%e6%8e%92%e5%ba%8f%e7%b5%90%e6%9e%9c%ef%bc%9aorder-by-%e5%ad%90%e5%8f%a5-cOKTUCfjcf\">\u6392\u5e8f\u7d50\u679c\uff1aORDER BY \u5b50\u53e5<\/h2>\n<p>\u4f7f\u7528 <code>ORDER BY<\/code> \u5b50\u53e5\u53ef\u4ee5\u5c0d\u67e5\u8a62\u7d50\u679c\u9032\u884c\u6392\u5e8f\u3002\u9ed8\u8a8d\u60c5\u6cc1\u4e0b\uff0c\u6392\u5e8f\u662f\u6309\u5347\u5e8f\u9032\u884c\u7684\uff0c\u4f46\u53ef\u4ee5\u4f7f\u7528 <code>DESC<\/code> \u4f86\u6307\u5b9a\u964d\u5e8f\u3002\u4f8b\u5982\uff0c\u82e5\u8981\u6309\u85aa\u6c34\u964d\u5e8f\u6392\u5217\u7d93\u7406\u7684\u540d\u55ae\uff0c\u53ef\u4ee5\u9019\u6a23\u5beb\uff1a<\/p>\n<pre><code>SELECT name, salary\nFROM employees\nWHERE position = '\u7d93\u7406'\nORDER BY salary DESC;<\/code><\/pre>\n<h2 id=\"%e9%99%90%e5%88%b6%e7%b5%90%e6%9e%9c%ef%bc%9alimit-%e5%ad%90%e5%8f%a5-cOKTUCfjcf\">\u9650\u5236\u7d50\u679c\uff1aLIMIT \u5b50\u53e5<\/h2>\n<p>\u5728\u67d0\u4e9b\u60c5\u6cc1\u4e0b\uff0c\u4f60\u53ef\u80fd\u53ea\u60f3\u7372\u53d6\u67e5\u8a62\u7d50\u679c\u7684\u524d\u5e7e\u689d\u8a18\u9304\u3002\u9019\u6642\u53ef\u4ee5\u4f7f\u7528 <code>LIMIT<\/code> \u5b50\u53e5\u3002\u4f8b\u5982\uff0c\u82e5\u8981\u67e5\u8a62\u524d 5 \u540d\u85aa\u6c34\u6700\u9ad8\u7684\u54e1\u5de5\uff0c\u53ef\u4ee5\u9019\u6a23\u5beb\uff1a<\/p>\n<pre><code>SELECT name, salary\nFROM employees\nORDER BY salary DESC\nLIMIT 5;<\/code><\/pre>\n<h2 id=\"%e7%b5%90%e5%90%88%e5%a4%9a%e5%80%8b%e6%a2%9d%e4%bb%b6-cOKTUCfjcf\">\u7d50\u5408\u591a\u500b\u689d\u4ef6<\/h2>\n<p>\u53ef\u4ee5\u4f7f\u7528 <code>AND<\/code> \u548c <code>OR<\/code> \u4f86\u7d50\u5408\u591a\u500b\u67e5\u8a62\u689d\u4ef6\u3002\u4f8b\u5982\uff0c\u5982\u679c\u6211\u5011\u60f3\u67e5\u8a62\u85aa\u6c34\u9ad8\u65bc 50000 \u4e14\u8077\u4f4d\u70ba\u300c\u7d93\u7406\u300d\u7684\u54e1\u5de5\uff0c\u53ef\u4ee5\u9019\u6a23\u5beb\uff1a<\/p>\n<pre><code>SELECT name, salary\nFROM employees\nWHERE position = '\u7d93\u7406' AND salary &gt; 50000;<\/code><\/pre>\n<h2 id=\"%e5%b0%8f%e7%b5%90-cOKTUCfjcf\">\u5c0f\u7d50<\/h2>\n<p>\u672c\u6587\u4ecb\u7d39\u4e86\u521d\u7d1a SQL <code>SELECT<\/code> \u8a9e\u6cd5\u7684\u57fa\u672c\u7528\u6cd5\uff0c\u5305\u62ec\u5982\u4f55\u67e5\u8a62\u7279\u5b9a\u5217\u3001\u4f7f\u7528\u689d\u4ef6\u904e\u6ffe\u7d50\u679c\u3001\u6392\u5e8f\u548c\u9650\u5236\u67e5\u8a62\u7d50\u679c\u7b49\u3002\u638c\u63e1\u9019\u4e9b\u57fa\u672c\u8a9e\u6cd5\u5f8c\uff0c\u8b80\u8005\u53ef\u4ee5\u66f4\u6709\u6548\u5730\u5f9e\u6578\u64da\u5eab\u4e2d\u63d0\u53d6\u6240\u9700\u7684\u4fe1\u606f\uff0c\u70ba\u5f8c\u7e8c\u7684\u6578\u64da\u5206\u6790\u548c\u61c9\u7528\u6253\u4e0b\u57fa\u790e\u3002<\/p>\n<p>\u5982\u9700\u9032\u4e00\u6b65\u4e86\u89e3\u5982\u4f55\u5728 <a href=\"https:\/\/server.hk\">\u9999\u6e2fVPS<\/a> \u4e0a\u904b\u884c\u6578\u64da\u5eab\uff0c\u6216\u5c0b\u627e\u5408\u9069\u7684 <a href=\"https:\/\/server.hk\">\u4e91\u670d\u52a1\u5668<\/a> \u89e3\u6c7a\u65b9\u6848\uff0c\u8acb\u8a2a\u554f\u6211\u5011\u7684\u7db2\u7ad9\u4ee5\u7372\u53d6\u66f4\u591a\u4fe1\u606f\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u5b78\u7fd2\u521d\u7d1a SQL SELECT \u8a9e\u6cd5\uff0c\u638c\u63e1\u6578\u64da\u67e5\u8a62\u6280\u5de7\uff0c\u8f15\u9b06\u63d0\u53d6\u548c\u5206\u6790\u8cc7\u6599\uff0c\u63d0\u5347\u6578\u64da\u8655\u7406\u80fd\u529b\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-152907","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/152907","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=152907"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/152907\/revisions"}],"predecessor-version":[{"id":152908,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/152907\/revisions\/152908"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=152907"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=152907"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=152907"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}