{"id":168467,"date":"2024-11-06T12:37:24","date_gmt":"2024-11-06T04:37:24","guid":{"rendered":"https:\/\/server.hk\/cnblog\/168467\/"},"modified":"2024-11-06T12:37:24","modified_gmt":"2024-11-06T04:37:24","slug":"sql-%e8%aa%9e%e5%8f%a5%e5%9c%a8-mysql-%e4%b8%ad%e6%98%af%e5%a6%82%e4%bd%95%e8%a2%ab%e5%9f%b7%e8%a1%8c%e7%9a%84%ef%bc%9f","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/168467\/","title":{"rendered":"SQL \u8a9e\u53e5\u5728 MySQL \u4e2d\u662f\u5982\u4f55\u88ab\u57f7\u884c\u7684\uff1f"},"content":{"rendered":"<h1 id=\"sql-%e8%aa%9e%e5%8f%a5%e5%9c%a8-mysql-%e4%b8%ad%e6%98%af%e5%a6%82%e4%bd%95%e8%a2%ab%e5%9f%b7%e8%a1%8c%e7%9a%84%ef%bc%9f-qbThZfUnzw\">SQL \u8a9e\u53e5\u5728 MySQL \u4e2d\u662f\u5982\u4f55\u88ab\u57f7\u884c\u7684\uff1f<\/h1>\n<p>\u5728\u7576\u4eca\u7684\u6578\u64da\u9a45\u52d5\u4e16\u754c\u4e2d\uff0cSQL\uff08\u7d50\u69cb\u5316\u67e5\u8a62\u8a9e\u8a00\uff09\u662f\u8207\u6578\u64da\u5eab\u9032\u884c\u4ea4\u4e92\u7684\u4e3b\u8981\u5de5\u5177\u4e4b\u4e00\u3002MySQL \u4f5c\u70ba\u4e00\u500b\u6d41\u884c\u7684\u958b\u6e90\u6578\u64da\u5eab\u7ba1\u7406\u7cfb\u7d71\uff0c\u5ee3\u6cdb\u61c9\u7528\u65bc\u5404\u7a2e\u61c9\u7528\u7a0b\u5e8f\u4e2d\u3002\u672c\u6587\u5c07\u6df1\u5165\u63a2\u8a0e SQL \u8a9e\u53e5\u5728 MySQL \u4e2d\u7684\u57f7\u884c\u904e\u7a0b\uff0c\u5e6b\u52a9\u8b80\u8005\u66f4\u597d\u5730\u7406\u89e3\u5176\u80cc\u5f8c\u7684\u904b\u4f5c\u539f\u7406\u3002<\/p>\n<h2 id=\"sql-%e8%aa%9e%e5%8f%a5%e7%9a%84%e5%9f%ba%e6%9c%ac%e7%b5%90%e6%a7%8b-qbThZfUnzw\">SQL \u8a9e\u53e5\u7684\u57fa\u672c\u7d50\u69cb<\/h2>\n<p>SQL \u8a9e\u53e5\u901a\u5e38\u7531\u95dc\u9375\u5b57\u3001\u8868\u540d\u3001\u5217\u540d\u548c\u689d\u4ef6\u7d44\u6210\u3002\u4ee5\u4e0b\u662f\u4e00\u500b\u7c21\u55ae\u7684 SQL \u67e5\u8a62\u7bc4\u4f8b\uff1a<\/p>\n<pre><code>SELECT name, age FROM users WHERE age &gt; 18;<\/code><\/pre>\n<p>\u9019\u689d\u8a9e\u53e5\u7684\u76ee\u7684\u662f\u5f9e\u540d\u70ba &#8220;users&#8221; \u7684\u8868\u4e2d\u9078\u64c7\u6240\u6709\u5e74\u9f61\u5927\u65bc 18 \u7684\u7528\u6236\u7684\u59d3\u540d\u548c\u5e74\u9f61\u3002<\/p>\n<h2 id=\"sql-%e8%aa%9e%e5%8f%a5%e7%9a%84%e5%9f%b7%e8%a1%8c%e9%81%8e%e7%a8%8b-qbThZfUnzw\">SQL \u8a9e\u53e5\u7684\u57f7\u884c\u904e\u7a0b<\/h2>\n<p>\u7576\u4e00\u689d SQL \u8a9e\u53e5\u88ab\u767c\u9001\u5230 MySQL \u4f3a\u670d\u5668\u6642\uff0c\u5b83\u6703\u7d93\u6b77\u4ee5\u4e0b\u5e7e\u500b\u4e3b\u8981\u6b65\u9a5f\uff1a<\/p>\n<h3 id=\"1-%e8%a7%a3%e6%9e%90%ef%bc%88parsing%ef%bc%89-qbThZfUnzw\">1. \u89e3\u6790\uff08Parsing\uff09<\/h3>\n<p>\u5728\u9019\u500b\u968e\u6bb5\uff0cMySQL \u6703\u5c0d SQL \u8a9e\u53e5\u9032\u884c\u8a9e\u6cd5\u5206\u6790\u3002\u89e3\u6790\u5668\u6703\u6aa2\u67e5\u8a9e\u53e5\u7684\u8a9e\u6cd5\u662f\u5426\u6b63\u78ba\uff0c\u4e26\u5c07\u5176\u8f49\u63db\u70ba\u5167\u90e8\u8868\u793a\u5f62\u5f0f\u3002\u5982\u679c\u8a9e\u6cd5\u932f\u8aa4\uff0cMySQL \u6703\u8fd4\u56de\u932f\u8aa4\u4fe1\u606f\u3002<\/p>\n<h3 id=\"2-%e5%84%aa%e5%8c%96%ef%bc%88optimization%ef%bc%89-qbThZfUnzw\">2. \u512a\u5316\uff08Optimization\uff09<\/h3>\n<p>\u4e00\u65e6 SQL \u8a9e\u53e5\u88ab\u89e3\u6790\uff0cMySQL \u6703\u9032\u5165\u512a\u5316\u968e\u6bb5\u3002\u5728\u9019\u500b\u968e\u6bb5\uff0c\u67e5\u8a62\u512a\u5316\u5668\u6703\u8a55\u4f30\u4e0d\u540c\u7684\u57f7\u884c\u8a08\u5283\uff0c\u9078\u64c7\u6700\u6709\u6548\u7684\u65b9\u5f0f\u4f86\u57f7\u884c\u67e5\u8a62\u3002\u9019\u53ef\u80fd\u5305\u62ec\u9078\u64c7\u5408\u9069\u7684\u7d22\u5f15\u3001\u91cd\u5beb\u67e5\u8a62\u4ee5\u63d0\u9ad8\u6548\u7387\u7b49\u3002<\/p>\n<h3 id=\"3-%e5%9f%b7%e8%a1%8c%ef%bc%88execution%ef%bc%89-qbThZfUnzw\">3. \u57f7\u884c\uff08Execution\uff09<\/h3>\n<p>\u5728\u78ba\u5b9a\u4e86\u6700\u4f73\u7684\u57f7\u884c\u8a08\u5283\u5f8c\uff0cMySQL \u6703\u958b\u59cb\u57f7\u884c\u67e5\u8a62\u3002\u9019\u500b\u904e\u7a0b\u6d89\u53ca\u5230\u5f9e\u6578\u64da\u5eab\u4e2d\u6aa2\u7d22\u6578\u64da\uff0c\u4e26\u6839\u64da\u67e5\u8a62\u7684\u8981\u6c42\u9032\u884c\u8655\u7406\u3002\u57f7\u884c\u7d50\u679c\u6703\u88ab\u8fd4\u56de\u7d66\u7528\u6236\u3002<\/p>\n<h3 id=\"4-%e8%bf%94%e5%9b%9e%e7%b5%90%e6%9e%9c%ef%bc%88result-return%ef%bc%89-qbThZfUnzw\">4. \u8fd4\u56de\u7d50\u679c\uff08Result Return\uff09<\/h3>\n<p>\u6700\u5f8c\uff0cMySQL \u6703\u5c07\u67e5\u8a62\u7d50\u679c\u8fd4\u56de\u7d66\u5ba2\u6236\u7aef\u61c9\u7528\u7a0b\u5e8f\u3002\u9019\u4e9b\u7d50\u679c\u53ef\u4ee5\u662f\u67e5\u8a62\u7684\u6578\u64da\u96c6\uff0c\u4e5f\u53ef\u4ee5\u662f\u57f7\u884c\u6210\u529f\u6216\u5931\u6557\u7684\u72c0\u614b\u4fe1\u606f\u3002<\/p>\n<h2 id=\"%e6%9f%a5%e8%a9%a2%e5%84%aa%e5%8c%96%e7%9a%84%e6%8a%80%e5%b7%a7-qbThZfUnzw\">\u67e5\u8a62\u512a\u5316\u7684\u6280\u5de7<\/h2>\n<p>\u70ba\u4e86\u63d0\u9ad8 SQL \u67e5\u8a62\u7684\u6027\u80fd\uff0c\u958b\u767c\u8005\u53ef\u4ee5\u63a1\u53d6\u4ee5\u4e0b\u5e7e\u500b\u512a\u5316\u6280\u5de7\uff1a<\/p>\n<ul>\n<li><strong>\u4f7f\u7528\u7d22\u5f15\uff1a<\/strong>\u7d22\u5f15\u53ef\u4ee5\u986f\u8457\u63d0\u9ad8\u67e5\u8a62\u901f\u5ea6\uff0c\u7279\u5225\u662f\u5728\u5927\u578b\u6578\u64da\u96c6\u4e0a\u3002<\/li>\n<li><strong>\u907f\u514d SELECT *\uff1a<\/strong>\u53ea\u9078\u64c7\u9700\u8981\u7684\u5217\uff0c\u9019\u6a23\u53ef\u4ee5\u6e1b\u5c11\u6578\u64da\u50b3\u8f38\u7684\u8ca0\u64d4\u3002<\/li>\n<li><strong>\u4f7f\u7528 JOIN \u800c\u975e\u5b50\u67e5\u8a62\uff1a<\/strong>\u5728\u67d0\u4e9b\u60c5\u6cc1\u4e0b\uff0c\u4f7f\u7528 JOIN \u4f86\u9023\u63a5\u8868\u6bd4\u4f7f\u7528\u5b50\u67e5\u8a62\u66f4\u9ad8\u6548\u3002<\/li>\n<li><strong>\u5b9a\u671f\u5206\u6790\u548c\u512a\u5316\u8868\uff1a<\/strong>\u4f7f\u7528 MySQL \u7684 ANALYZE TABLE \u548c OPTIMIZE TABLE \u547d\u4ee4\u4f86\u4fdd\u6301\u6578\u64da\u5eab\u6027\u80fd\u3002<\/li>\n<\/ul>\n<h2 id=\"%e7%b5%90%e8%ab%96-qbThZfUnzw\">\u7d50\u8ad6<\/h2>\n<p>\u4e86\u89e3 SQL \u8a9e\u53e5\u5728 MySQL \u4e2d\u7684\u57f7\u884c\u904e\u7a0b\u5c0d\u65bc\u958b\u767c\u8005\u548c\u6578\u64da\u5eab\u7ba1\u7406\u54e1\u4f86\u8aaa\u81f3\u95dc\u91cd\u8981\u3002\u901a\u904e\u638c\u63e1\u89e3\u6790\u3001\u512a\u5316\u548c\u57f7\u884c\u7684\u904e\u7a0b\uff0c\u958b\u767c\u8005\u53ef\u4ee5\u7de8\u5beb\u66f4\u9ad8\u6548\u7684\u67e5\u8a62\uff0c\u5f9e\u800c\u63d0\u5347\u61c9\u7528\u7a0b\u5e8f\u7684\u6027\u80fd\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\u4e5f\u662f\u4e00\u500b\u91cd\u8981\u7684\u8003\u91cf\uff0c\u9019\u6a23\u53ef\u4ee5\u78ba\u4fdd\u6578\u64da\u5eab\u7684\u7a69\u5b9a\u6027\u548c\u53ef\u9760\u6027\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4e86\u89e3 SQL \u8a9e\u53e5\u5728 MySQL 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