{"id":74787,"date":"2024-10-15T22:53:14","date_gmt":"2024-10-15T14:53:14","guid":{"rendered":"https:\/\/server.hk\/cnblog\/74787\/"},"modified":"2024-10-15T22:53:14","modified_gmt":"2024-10-15T14:53:14","slug":"mysql-select%e6%8a%80%e5%b7%a7%e4%bd%bf%e7%94%a8%e5%a4%a7%e5%85%a8","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/74787\/","title":{"rendered":"MySQL SELECT\u6280\u5de7\u4f7f\u7528\u5927\u5168"},"content":{"rendered":"<h1 id=\"mysql-select%e6%8a%80%e5%b7%a7%e4%bd%bf%e7%94%a8%e5%a4%a7%e5%85%a8-vjpmNUWXrZ\">MySQL SELECT\u6280\u5de7\u4f7f\u7528\u5927\u5168<\/h1>\n<p>MySQL \u662f\u4e00\u7a2e\u6d41\u884c\u7684\u95dc\u806f\u5f0f\u8cc7\u6599\u5eab\u7ba1\u7406\u7cfb\u7d71\uff0c\u5ee3\u6cdb\u61c9\u7528\u65bc\u5404\u7a2e\u7db2\u7ad9\u548c\u61c9\u7528\u7a0b\u5f0f\u4e2d\u3002SELECT \u8a9e\u53e5\u662f MySQL \u4e2d\u6700\u5e38\u7528\u7684\u67e5\u8a62\u8a9e\u53e5\u4e4b\u4e00\uff0c\u80fd\u5920\u5f9e\u8cc7\u6599\u8868\u4e2d\u6aa2\u7d22\u6240\u9700\u7684\u8cc7\u6599\u3002\u672c\u6587\u5c07\u4ecb\u7d39 MySQL SELECT \u8a9e\u53e5\u7684\u5404\u7a2e\u6280\u5de7\uff0c\u5e6b\u52a9\u4f7f\u7528\u8005\u66f4\u6709\u6548\u5730\u9032\u884c\u8cc7\u6599\u67e5\u8a62\u3002<\/p>\n<h2 id=\"%e5%9f%ba%e6%9c%ac%e7%9a%84-select-%e8%aa%9e%e5%8f%a5-vjpmNUWXrZ\">\u57fa\u672c\u7684 SELECT \u8a9e\u53e5<\/h2>\n<p>\u6700\u57fa\u672c\u7684 SELECT \u8a9e\u53e5\u683c\u5f0f\u5982\u4e0b\uff1a<\/p>\n<pre><code>SELECT column1, column2 FROM table_name;<\/code><\/pre>\n<p>\u4f8b\u5982\uff0c\u82e5\u8981\u5f9e\u540d\u70ba &#8220;users&#8221; \u7684\u8cc7\u6599\u8868\u4e2d\u9078\u64c7 &#8220;name&#8221; \u548c &#8220;email&#8221; \u5169\u500b\u6b04\u4f4d\uff0c\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b\u8a9e\u53e5\uff1a<\/p>\n<pre><code>SELECT name, email FROM users;<\/code><\/pre>\n<h2 id=\"%e4%bd%bf%e7%94%a8-where-%e5%ad%90%e5%8f%a5%e9%80%b2%e8%a1%8c%e6%a2%9d%e4%bb%b6%e6%9f%a5%e8%a9%a2-vjpmNUWXrZ\">\u4f7f\u7528 WHERE \u5b50\u53e5\u9032\u884c\u689d\u4ef6\u67e5\u8a62<\/h2>\n<p>\u5728\u67e5\u8a62\u4e2d\uff0c\u5e38\u5e38\u9700\u8981\u6839\u64da\u7279\u5b9a\u689d\u4ef6\u904e\u6ffe\u8cc7\u6599\u3002\u9019\u6642\u53ef\u4ee5\u4f7f\u7528 WHERE \u5b50\u53e5\u3002\u4f8b\u5982\uff0c\u82e5\u8981\u67e5\u8a62\u5e74\u9f61\u5927\u65bc 18 \u6b72\u7684\u4f7f\u7528\u8005\uff0c\u53ef\u4ee5\u9019\u6a23\u5beb\uff1a<\/p>\n<pre><code>SELECT * FROM users WHERE age &gt; 18;<\/code><\/pre>\n<h2 id=\"%e6%8e%92%e5%ba%8f%e7%b5%90%e6%9e%9c%ef%bc%9aorder-by-vjpmNUWXrZ\">\u6392\u5e8f\u7d50\u679c\uff1aORDER BY<\/h2>\n<p>\u4f7f\u7528 ORDER BY \u5b50\u53e5\u53ef\u4ee5\u5c0d\u67e5\u8a62\u7d50\u679c\u9032\u884c\u6392\u5e8f\u3002\u9810\u8a2d\u70ba\u5347\u5e8f\u6392\u5217\uff0c\u82e5\u8981\u964d\u5e8f\u6392\u5217\uff0c\u53ef\u4ee5\u4f7f\u7528 DESC \u95dc\u9375\u5b57\u3002\u4f8b\u5982\uff1a<\/p>\n<pre><code>SELECT * FROM users ORDER BY age DESC;<\/code><\/pre>\n<h2 id=\"%e9%99%90%e5%88%b6%e6%9f%a5%e8%a9%a2%e7%b5%90%e6%9e%9c%ef%bc%9alimit-vjpmNUWXrZ\">\u9650\u5236\u67e5\u8a62\u7d50\u679c\uff1aLIMIT<\/h2>\n<p>\u5728\u67d0\u4e9b\u60c5\u6cc1\u4e0b\uff0c\u60a8\u53ef\u80fd\u53ea\u60f3\u6aa2\u7d22\u90e8\u5206\u7d50\u679c\u3002LIMIT \u5b50\u53e5\u53ef\u4ee5\u5e6b\u52a9\u60a8\u9650\u5236\u8fd4\u56de\u7684\u884c\u6578\u3002\u4f8b\u5982\uff0c\u82e5\u53ea\u60f3\u7372\u53d6\u524d 5 \u689d\u8a18\u9304\uff1a<\/p>\n<pre><code>SELECT * FROM users LIMIT 5;<\/code><\/pre>\n<h2 id=\"%e4%bd%bf%e7%94%a8-distinct-%e9%81%8e%e6%bf%be%e9%87%8d%e8%a4%87%e5%80%bc-vjpmNUWXrZ\">\u4f7f\u7528 DISTINCT \u904e\u6ffe\u91cd\u8907\u503c<\/h2>\n<p>\u7576\u67e5\u8a62\u7d50\u679c\u4e2d\u53ef\u80fd\u5305\u542b\u91cd\u8907\u7684\u503c\u6642\uff0c\u53ef\u4ee5\u4f7f\u7528 DISTINCT \u95dc\u9375\u5b57\u4f86\u904e\u6ffe\u91cd\u8907\u7684\u884c\u3002\u4f8b\u5982\uff0c\u82e5\u8981\u67e5\u8a62\u6240\u6709\u4e0d\u540c\u7684\u57ce\u5e02\uff1a<\/p>\n<pre><code>SELECT DISTINCT city FROM users;<\/code><\/pre>\n<h2 id=\"%e8%81%af%e6%8e%a5%e5%a4%9a%e5%80%8b%e8%b3%87%e6%96%99%e8%a1%a8%ef%bc%9ajoin-vjpmNUWXrZ\">\u806f\u63a5\u591a\u500b\u8cc7\u6599\u8868\uff1aJOIN<\/h2>\n<p>\u5728\u5be6\u969b\u61c9\u7528\u4e2d\uff0c\u7d93\u5e38\u9700\u8981\u5f9e\u591a\u500b\u8cc7\u6599\u8868\u4e2d\u6aa2\u7d22\u8cc7\u6599\u3002JOIN \u8a9e\u53e5\u53ef\u4ee5\u5c07\u591a\u500b\u8cc7\u6599\u8868\u806f\u63a5\u5728\u4e00\u8d77\u3002\u4f8b\u5982\uff0c\u82e5\u8981\u5f9e &#8220;users&#8221; \u548c &#8220;orders&#8221; \u5169\u500b\u8cc7\u6599\u8868\u4e2d\u67e5\u8a62\u4f7f\u7528\u8005\u53ca\u5176\u8a02\u55ae\uff0c\u53ef\u4ee5\u9019\u6a23\u5beb\uff1a<\/p>\n<pre><code>SELECT users.name, orders.product FROM users JOIN orders ON users.id = orders.user_id;<\/code><\/pre>\n<h2 id=\"%e4%bd%bf%e7%94%a8-group-by-%e5%92%8c%e8%81%9a%e5%90%88%e5%87%bd%e6%95%b8-vjpmNUWXrZ\">\u4f7f\u7528 GROUP BY \u548c\u805a\u5408\u51fd\u6578<\/h2>\n<p>\u7576\u9700\u8981\u5c0d\u67e5\u8a62\u7d50\u679c\u9032\u884c\u5206\u7d44\u4e26\u8a08\u7b97\u805a\u5408\u503c\u6642\uff0c\u53ef\u4ee5\u4f7f\u7528 GROUP BY \u5b50\u53e5\u548c\u805a\u5408\u51fd\u6578\uff08\u5982 COUNT\u3001SUM\u3001AVG \u7b49\uff09\u3002\u4f8b\u5982\uff0c\u82e5\u8981\u67e5\u8a62\u6bcf\u500b\u57ce\u5e02\u7684\u4f7f\u7528\u8005\u6578\u91cf\uff1a<\/p>\n<pre><code>SELECT city, COUNT(*) FROM users GROUP BY city;<\/code><\/pre>\n<h2 id=\"%e5%ad%90%e6%9f%a5%e8%a9%a2%e7%9a%84%e4%bd%bf%e7%94%a8-vjpmNUWXrZ\">\u5b50\u67e5\u8a62\u7684\u4f7f\u7528<\/h2>\n<p>\u5b50\u67e5\u8a62\u662f\u6307\u5728\u4e00\u500b\u67e5\u8a62\u4e2d\u5d4c\u5957\u53e6\u4e00\u500b\u67e5\u8a62\u3002\u9019\u5728\u9700\u8981\u6839\u64da\u5176\u4ed6\u67e5\u8a62\u7684\u7d50\u679c\u9032\u884c\u904e\u6ffe\u6642\u975e\u5e38\u6709\u7528\u3002\u4f8b\u5982\uff0c\u82e5\u8981\u67e5\u8a62\u6240\u6709\u8a02\u8cfc\u4e86\u7279\u5b9a\u7522\u54c1\u7684\u4f7f\u7528\u8005\uff0c\u53ef\u4ee5\u9019\u6a23\u5beb\uff1a<\/p>\n<pre><code>SELECT * FROM users WHERE id IN (SELECT user_id FROM orders WHERE product = '\u7279\u5b9a\u7522\u54c1');<\/code><\/pre>\n<h2 id=\"%e7%b5%90%e8%ab%96-vjpmNUWXrZ\">\u7d50\u8ad6<\/h2>\n<p>MySQL \u7684 SELECT \u8a9e\u53e5\u63d0\u4f9b\u4e86\u591a\u7a2e\u5f37\u5927\u7684\u529f\u80fd\uff0c\u80fd\u5920\u5e6b\u52a9\u4f7f\u7528\u8005\u9748\u6d3b\u5730\u6aa2\u7d22\u548c\u64cd\u4f5c\u8cc7\u6599\u3002\u638c\u63e1\u9019\u4e9b\u6280\u5de7\u4e0d\u50c5\u80fd\u63d0\u9ad8\u67e5\u8a62\u6548\u7387\uff0c\u9084\u80fd\u4f7f\u8cc7\u6599\u7ba1\u7406\u8b8a\u5f97\u66f4\u52a0\u7c21\u55ae\u3002\u7121\u8ad6\u662f\u57fa\u672c\u7684\u67e5\u8a62\u9084\u662f\u8907\u96dc\u7684\u806f\u63a5\u548c\u805a\u5408\uff0c\u719f\u6089\u9019\u4e9b\u8a9e\u6cd5\u90fd\u5c07\u5c0d\u60a8\u7684\u8cc7\u6599\u5eab\u64cd\u4f5c\u5927\u6709\u88e8\u76ca\u3002<\/p>\n<p>\u5982\u9700\u9032\u4e00\u6b65\u4e86\u89e3\u5982\u4f55\u5728 <a href=\"https:\/\/server.hk\">\u9999\u6e2f\u4f3a\u670d\u5668<\/a> \u4e0a\u4f7f\u7528 MySQL\uff0c\u6216\u5c0b\u627e\u5408\u9069\u7684 <a href=\"https:\/\/server.hk\">VPS<\/a> \u89e3\u6c7a\u65b9\u6848\uff0c\u8acb\u8a2a\u554f\u6211\u5011\u7684\u7db2\u7ad9\u4ee5\u7372\u53d6\u66f4\u591a\u8cc7\u8a0a\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Discover essential MySQL SELECT tips and techniques to enhance your database queries and optimize performance in this comprehensive guide.<\/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-74787","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/74787","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=74787"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/74787\/revisions"}],"predecessor-version":[{"id":74788,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/74787\/revisions\/74788"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=74787"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=74787"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=74787"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}