{"id":174515,"date":"2024-11-07T22:31:22","date_gmt":"2024-11-07T14:31:22","guid":{"rendered":"https:\/\/server.hk\/cnblog\/174515\/"},"modified":"2024-11-07T22:31:22","modified_gmt":"2024-11-07T14:31:22","slug":"%e5%a6%82%e4%bd%95%e5%bf%ab%e9%80%9f%e6%9f%a5%e6%89%be%e6%95%b8%e6%93%9a%e5%ba%ab%e4%b8%ad%e7%9a%84%e7%89%b9%e5%ae%9a%e6%95%b8%e5%80%bc%ef%bc%9f-%e6%9f%a5%e6%89%be%e6%95%b8%e6%93%9a%e5%ba%ab%e6%9f%90","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/174515\/","title":{"rendered":"\u5982\u4f55\u5feb\u901f\u67e5\u627e\u6578\u64da\u5eab\u4e2d\u7684\u7279\u5b9a\u6578\u503c\uff1f (\u67e5\u627e\u6578\u64da\u5eab\u67d0\u500b\u503c)"},"content":{"rendered":"<h1 id=\"%e5%a6%82%e4%bd%95%e5%bf%ab%e9%80%9f%e6%9f%a5%e6%89%be%e6%95%b8%e6%93%9a%e5%ba%ab%e4%b8%ad%e7%9a%84%e7%89%b9%e5%ae%9a%e6%95%b8%e5%80%bc%ef%bc%9f-gLjfbaPkRn\">\u5982\u4f55\u5feb\u901f\u67e5\u627e\u6578\u64da\u5eab\u4e2d\u7684\u7279\u5b9a\u6578\u503c\uff1f<\/h1>\n<p>\u5728\u7576\u4eca\u6578\u64da\u9a45\u52d5\u7684\u4e16\u754c\u4e2d\uff0c\u6578\u64da\u5eab\u7684\u7ba1\u7406\u548c\u67e5\u8a62\u8b8a\u5f97\u8d8a\u4f86\u8d8a\u91cd\u8981\u3002\u7121\u8ad6\u662f\u4f01\u696d\u9084\u662f\u500b\u4eba\uff0c\u80fd\u5920\u5feb\u901f\u6709\u6548\u5730\u67e5\u627e\u6578\u64da\u5eab\u4e2d\u7684\u7279\u5b9a\u6578\u503c\u90fd\u662f\u4e00\u9805\u57fa\u672c\u6280\u80fd\u3002\u672c\u6587\u5c07\u63a2\u8a0e\u5982\u4f55\u5728\u6578\u64da\u5eab\u4e2d\u5feb\u901f\u67e5\u627e\u7279\u5b9a\u503c\uff0c\u4e26\u63d0\u4f9b\u4e00\u4e9b\u5be6\u7528\u7684\u6280\u5de7\u548c\u793a\u4f8b\u3002<\/p>\n<h2 id=\"%e6%95%b8%e6%93%9a%e5%ba%ab%e6%9f%a5%e8%a9%a2%e7%9a%84%e5%9f%ba%e6%9c%ac%e6%a6%82%e5%bf%b5-gLjfbaPkRn\">\u6578\u64da\u5eab\u67e5\u8a62\u7684\u57fa\u672c\u6982\u5ff5<\/h2>\n<p>\u6578\u64da\u5eab\u67e5\u8a62\u662f\u6307\u5f9e\u6578\u64da\u5eab\u4e2d\u6aa2\u7d22\u6578\u64da\u7684\u904e\u7a0b\u3002\u6700\u5e38\u7528\u7684\u67e5\u8a62\u8a9e\u8a00\u662f\u7d50\u69cb\u5316\u67e5\u8a62\u8a9e\u8a00\uff08SQL\uff09\u3002SQL \u63d0\u4f9b\u4e86\u4e00\u7cfb\u5217\u547d\u4ee4\u4f86\u64cd\u4f5c\u548c\u67e5\u8a62\u6578\u64da\u5eab\u4e2d\u7684\u6578\u64da\u3002\u8981\u67e5\u627e\u7279\u5b9a\u6578\u503c\uff0c\u901a\u5e38\u4f7f\u7528 <code>SELECT<\/code> \u8a9e\u53e5\u3002<\/p>\n<h3 id=\"%e5%9f%ba%e6%9c%ac%e7%9a%84-sql-%e6%9f%a5%e8%a9%a2%e8%aa%9e%e6%b3%95-gLjfbaPkRn\">\u57fa\u672c\u7684 SQL \u67e5\u8a62\u8a9e\u6cd5<\/h3>\n<p>\u4e00\u500b\u57fa\u672c\u7684 SQL \u67e5\u8a62\u8a9e\u6cd5\u5982\u4e0b\uff1a<\/p>\n<pre><code>SELECT column1, column2, ...\nFROM table_name\nWHERE condition;<\/code><\/pre>\n<p>\u5728\u9019\u88e1\uff0c<code>column1, column2, ...<\/code> \u662f\u4f60\u60f3\u8981\u6aa2\u7d22\u7684\u5217\uff0c<code>table_name<\/code> \u662f\u6578\u64da\u8868\u7684\u540d\u7a31\uff0c\u800c <code>condition<\/code> \u5247\u662f\u7528\u4f86\u904e\u6ffe\u6578\u64da\u7684\u689d\u4ef6\u3002<\/p>\n<h2 id=\"%e6%9f%a5%e6%89%be%e7%89%b9%e5%ae%9a%e6%95%b8%e5%80%bc%e7%9a%84%e6%ad%a5%e9%a9%9f-gLjfbaPkRn\">\u67e5\u627e\u7279\u5b9a\u6578\u503c\u7684\u6b65\u9a5f<\/h2>\n<h3 id=\"1-%e7%a2%ba%e5%ae%9a%e6%95%b8%e6%93%9a%e8%a1%a8%e5%92%8c%e5%88%97-gLjfbaPkRn\">1. \u78ba\u5b9a\u6578\u64da\u8868\u548c\u5217<\/h3>\n<p>\u9996\u5148\uff0c\u4f60\u9700\u8981\u77e5\u9053\u8981\u67e5\u627e\u7684\u6578\u64da\u6240\u5728\u7684\u6578\u64da\u8868\u53ca\u5176\u5217\u540d\u3002\u4f8b\u5982\uff0c\u5047\u8a2d\u6211\u5011\u6709\u4e00\u500b\u540d\u70ba <code>employees<\/code> \u7684\u8868\uff0c\u4e26\u4e14\u6211\u5011\u60f3\u67e5\u627e\u67d0\u500b\u54e1\u5de5\u7684\u59d3\u540d\u3002<\/p>\n<h3 id=\"2-%e7%b7%a8%e5%af%ab%e6%9f%a5%e8%a9%a2%e8%aa%9e%e5%8f%a5-gLjfbaPkRn\">2. \u7de8\u5beb\u67e5\u8a62\u8a9e\u53e5<\/h3>\n<p>\u63a5\u4e0b\u4f86\uff0c\u7de8\u5beb SQL \u67e5\u8a62\u8a9e\u53e5\u4f86\u67e5\u627e\u7279\u5b9a\u7684\u6578\u503c\u3002\u5047\u8a2d\u6211\u5011\u8981\u67e5\u627e\u540d\u70ba &#8220;John&#8221; \u7684\u54e1\u5de5\uff0c\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b\u67e5\u8a62\uff1a<\/p>\n<pre><code>SELECT * FROM employees WHERE name = 'John';<\/code><\/pre>\n<p>\u9019\u689d\u8a9e\u53e5\u5c07\u8fd4\u56de\u6240\u6709\u540d\u70ba &#8220;John&#8221; \u7684\u54e1\u5de5\u7684\u8a18\u9304\u3002<\/p>\n<h3 id=\"3-%e4%bd%bf%e7%94%a8%e9%80%9a%e9%85%8d%e7%ac%a6%e9%80%b2%e8%a1%8c%e6%a8%a1%e7%b3%8a%e6%9f%a5%e8%a9%a2-gLjfbaPkRn\">3. \u4f7f\u7528\u901a\u914d\u7b26\u9032\u884c\u6a21\u7cca\u67e5\u8a62<\/h3>\n<p>\u5982\u679c\u4f60\u4e0d\u78ba\u5b9a\u5b8c\u6574\u7684\u6578\u503c\uff0c\u53ef\u4ee5\u4f7f\u7528\u901a\u914d\u7b26\u9032\u884c\u6a21\u7cca\u67e5\u8a62\u3002\u4f8b\u5982\uff0c\u5982\u679c\u4f60\u60f3\u67e5\u627e\u6240\u6709\u4ee5 &#8220;Jo&#8221; \u958b\u982d\u7684\u59d3\u540d\uff0c\u53ef\u4ee5\u9019\u6a23\u5beb\uff1a<\/p>\n<pre><code>SELECT * FROM employees WHERE name LIKE 'Jo%';<\/code><\/pre>\n<p>\u9019\u689d\u8a9e\u53e5\u5c07\u8fd4\u56de\u6240\u6709\u4ee5 &#8220;Jo&#8221; \u958b\u982d\u7684\u54e1\u5de5\u59d3\u540d\u3002<\/p>\n<h2 id=\"%e6%8f%90%e9%ab%98%e6%9f%a5%e8%a9%a2%e6%95%88%e7%8e%87%e7%9a%84%e6%8a%80%e5%b7%a7-gLjfbaPkRn\">\u63d0\u9ad8\u67e5\u8a62\u6548\u7387\u7684\u6280\u5de7<\/h2>\n<h3 id=\"1-%e4%bd%bf%e7%94%a8%e7%b4%a2%e5%bc%95-gLjfbaPkRn\">1. \u4f7f\u7528\u7d22\u5f15<\/h3>\n<p>\u5728\u5927\u578b\u6578\u64da\u5eab\u4e2d\uff0c\u67e5\u8a62\u901f\u5ea6\u53ef\u80fd\u6703\u53d7\u5230\u5f71\u97ff\u3002\u70ba\u4e86\u63d0\u9ad8\u67e5\u8a62\u6548\u7387\uff0c\u53ef\u4ee5\u5728\u7d93\u5e38\u67e5\u8a62\u7684\u5217\u4e0a\u5275\u5efa\u7d22\u5f15\u3002\u7d22\u5f15\u53ef\u4ee5\u52a0\u901f\u6578\u64da\u6aa2\u7d22\uff0c\u4f46\u4e5f\u6703\u589e\u52a0\u5beb\u5165\u64cd\u4f5c\u7684\u6210\u672c\u3002<\/p>\n<pre><code>CREATE INDEX idx_name ON employees(name);<\/code><\/pre>\n<h3 id=\"2-%e9%99%90%e5%88%b6%e8%bf%94%e5%9b%9e%e7%9a%84%e8%a1%8c%e6%95%b8-gLjfbaPkRn\">2. \u9650\u5236\u8fd4\u56de\u7684\u884c\u6578<\/h3>\n<p>\u5982\u679c\u4f60\u53ea\u9700\u8981\u67e5\u627e\u7279\u5b9a\u6578\u91cf\u7684\u8a18\u9304\uff0c\u53ef\u4ee5\u4f7f\u7528 <code>LIMIT<\/code> \u5b50\u53e5\u4f86\u9650\u5236\u8fd4\u56de\u7684\u884c\u6578\u3002\u4f8b\u5982\uff1a<\/p>\n<pre><code>SELECT * FROM employees WHERE name = 'John' LIMIT 10;<\/code><\/pre>\n<h3 id=\"3-%e4%bd%bf%e7%94%a8%e8%81%9a%e5%90%88%e5%87%bd%e6%95%b8-gLjfbaPkRn\">3. \u4f7f\u7528\u805a\u5408\u51fd\u6578<\/h3>\n<p>\u5982\u679c\u4f60\u9700\u8981\u5c0d\u6578\u64da\u9032\u884c\u7d71\u8a08\u5206\u6790\uff0c\u53ef\u4ee5\u4f7f\u7528\u805a\u5408\u51fd\u6578\uff0c\u5982 <code>COUNT<\/code>\u3001<code>SUM<\/code>\u3001<code>AVG<\/code> \u7b49\u3002\u4f8b\u5982\uff0c\u8a08\u7b97\u540d\u70ba &#8220;John&#8221; \u7684\u54e1\u5de5\u6578\u91cf\uff1a<\/p>\n<pre><code>SELECT COUNT(*) FROM employees WHERE name = 'John';<\/code><\/pre>\n<h2 id=\"%e7%b8%bd%e7%b5%90-gLjfbaPkRn\">\u7e3d\u7d50<\/h2>\n<p>\u5feb\u901f\u67e5\u627e\u6578\u64da\u5eab\u4e2d\u7684\u7279\u5b9a\u6578\u503c\u662f\u4e00\u9805\u91cd\u8981\u7684\u6280\u80fd\uff0c\u638c\u63e1 SQL \u67e5\u8a62\u8a9e\u8a00\u7684\u57fa\u672c\u7528\u6cd5\u548c\u6280\u5de7\u53ef\u4ee5\u5927\u5927\u63d0\u9ad8\u5de5\u4f5c\u6548\u7387\u3002\u901a\u904e\u4f7f\u7528\u7d22\u5f15\u3001\u9650\u5236\u8fd4\u56de\u884c\u6578\u548c\u805a\u5408\u51fd\u6578\u7b49\u65b9\u6cd5\uff0c\u53ef\u4ee5\u9032\u4e00\u6b65\u512a\u5316\u67e5\u8a62\u6027\u80fd\u3002\u5c0d\u65bc\u9700\u8981\u9ad8\u6548\u6578\u64da\u7ba1\u7406\u7684\u7528\u6236\uff0c\u9078\u64c7\u5408\u9069\u7684 <a href=\"https:\/\/server.hk\">VPS<\/a> \u6216 <a href=\"https:\/\/server.hk\">\u9999\u6e2f\u4f3a\u670d\u5668<\/a> \u65b9\u6848\u4e5f\u662f\u4e00\u500b\u660e\u667a\u7684\u9078\u64c7\uff0c\u4ee5\u78ba\u4fdd\u6578\u64da\u5eab\u7684\u7a69\u5b9a\u6027\u548c\u5feb\u901f\u97ff\u61c9\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u5b78\u7fd2\u5982\u4f55\u5feb\u901f\u67e5\u627e\u6578\u64da\u5eab\u4e2d\u7684\u7279\u5b9a\u6578\u503c\uff0c\u638c\u63e1\u6709\u6548\u7684\u67e5\u8a62\u6280\u5de7\uff0c\u63d0\u5347\u6578\u64da\u6aa2\u7d22\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-174515","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/174515","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=174515"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/174515\/revisions"}],"predecessor-version":[{"id":174516,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/174515\/revisions\/174516"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=174515"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=174515"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=174515"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}