{"id":75634,"date":"2024-10-15T23:56:19","date_gmt":"2024-10-15T15:56:19","guid":{"rendered":"https:\/\/server.hk\/cnblog\/75634\/"},"modified":"2024-10-15T23:56:19","modified_gmt":"2024-10-15T15:56:19","slug":"mysql-%e6%95%b8%e6%93%9a%e5%ba%ab%e4%b8%ad%e8%a8%98%e9%8c%84%e4%b8%8d%e5%ad%98%e5%9c%a8%e6%99%82%e5%a6%82%e4%bd%95%e9%81%8b%e8%a1%8c%ef%bc%9f","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/75634\/","title":{"rendered":"MySQL \u6578\u64da\u5eab\u4e2d\u8a18\u9304\u4e0d\u5b58\u5728\u6642\u5982\u4f55\u904b\u884c\uff1f"},"content":{"rendered":"<h1 id=\"mysql-%e6%95%b8%e6%93%9a%e5%ba%ab%e4%b8%ad%e8%a8%98%e9%8c%84%e4%b8%8d%e5%ad%98%e5%9c%a8%e6%99%82%e5%a6%82%e4%bd%95%e9%81%8b%e8%a1%8c%ef%bc%9f-sfZJlDTuKu\">MySQL \u6578\u64da\u5eab\u4e2d\u8a18\u9304\u4e0d\u5b58\u5728\u6642\u5982\u4f55\u904b\u884c\uff1f<\/h1>\n<p>\u5728\u4f7f\u7528 MySQL \u6578\u64da\u5eab\u7684\u904e\u7a0b\u4e2d\uff0c\u958b\u767c\u8005\u7d93\u5e38\u6703\u9047\u5230\u67e5\u8a62\u67d0\u689d\u8a18\u9304\u6642\uff0c\u8a72\u8a18\u9304\u4e26\u4e0d\u5b58\u5728\u7684\u60c5\u6cc1\u3002\u9019\u7a2e\u60c5\u6cc1\u53ef\u80fd\u6703\u5c0e\u81f4\u61c9\u7528\u7a0b\u5e8f\u51fa\u73fe\u932f\u8aa4\u6216\u7570\u5e38\u884c\u70ba\uff0c\u56e0\u6b64\u4e86\u89e3\u5982\u4f55\u6b63\u78ba\u8655\u7406\u9019\u7a2e\u60c5\u6cc1\u662f\u975e\u5e38\u91cd\u8981\u7684\u3002\u672c\u6587\u5c07\u63a2\u8a0e\u5728 MySQL \u6578\u64da\u5eab\u4e2d\u8a18\u9304\u4e0d\u5b58\u5728\u6642\u7684\u904b\u884c\u65b9\u5f0f\uff0c\u4ee5\u53ca\u5982\u4f55\u6709\u6548\u5730\u7ba1\u7406\u9019\u4e9b\u60c5\u6cc1\u3002<\/p>\n<h2 id=\"1-%e6%9f%a5%e8%a9%a2%e4%b8%8d%e5%ad%98%e5%9c%a8%e7%9a%84%e8%a8%98%e9%8c%84-sfZJlDTuKu\">1. \u67e5\u8a62\u4e0d\u5b58\u5728\u7684\u8a18\u9304<\/h2>\n<p>\u7576\u6211\u5011\u57f7\u884c\u4e00\u500b\u67e5\u8a62\u6642\uff0c\u5982\u679c\u67e5\u8a62\u7684\u689d\u4ef6\u4e0d\u7b26\u5408\u4efb\u4f55\u73fe\u6709\u7684\u8a18\u9304\uff0cMySQL \u5c07\u8fd4\u56de\u4e00\u500b\u7a7a\u7d50\u679c\u96c6\u3002\u9019\u610f\u5473\u8457\u67e5\u8a62\u6210\u529f\u57f7\u884c\uff0c\u4f46\u6c92\u6709\u627e\u5230\u7b26\u5408\u689d\u4ef6\u7684\u6578\u64da\u3002\u4ee5\u4e0b\u662f\u4e00\u500b\u7c21\u55ae\u7684\u67e5\u8a62\u793a\u4f8b\uff1a<\/p>\n<pre><code>SELECT * FROM users WHERE id = 999;<\/code><\/pre>\n<p>\u5728\u9019\u500b\u4f8b\u5b50\u4e2d\uff0c\u5982\u679c ID \u70ba 999 \u7684\u7528\u6236\u4e0d\u5b58\u5728\uff0c\u5247\u67e5\u8a62\u5c07\u8fd4\u56de\u7a7a\u7d50\u679c\u96c6\u3002<\/p>\n<h2 id=\"2-%e8%99%95%e7%90%86%e7%a9%ba%e7%b5%90%e6%9e%9c%e9%9b%86-sfZJlDTuKu\">2. \u8655\u7406\u7a7a\u7d50\u679c\u96c6<\/h2>\n<p>\u5728\u61c9\u7528\u7a0b\u5e8f\u4e2d\uff0c\u958b\u767c\u8005\u9700\u8981\u5c0d\u7a7a\u7d50\u679c\u96c6\u9032\u884c\u8655\u7406\uff0c\u4ee5\u907f\u514d\u51fa\u73fe\u932f\u8aa4\u3002\u4ee5\u4e0b\u662f\u4e00\u4e9b\u5e38\u898b\u7684\u8655\u7406\u65b9\u6cd5\uff1a<\/p>\n<ul>\n<li><strong>\u6aa2\u67e5\u7d50\u679c\u96c6\uff1a<\/strong>\u5728\u7372\u53d6\u67e5\u8a62\u7d50\u679c\u5f8c\uff0c\u9996\u5148\u6aa2\u67e5\u7d50\u679c\u96c6\u662f\u5426\u70ba\u7a7a\u3002<\/li>\n<li><strong>\u8fd4\u56de\u9810\u8a2d\u503c\uff1a<\/strong>\u5982\u679c\u67e5\u8a62\u7d50\u679c\u70ba\u7a7a\uff0c\u53ef\u4ee5\u8fd4\u56de\u4e00\u500b\u9810\u8a2d\u503c\u6216\u63d0\u793a\u7528\u6236\u8a72\u8a18\u9304\u4e0d\u5b58\u5728\u3002<\/li>\n<li><strong>\u8a18\u9304\u65e5\u8a8c\uff1a<\/strong>\u5c0d\u65bc\u95dc\u9375\u64cd\u4f5c\uff0c\u53ef\u4ee5\u8a18\u9304\u65e5\u8a8c\u4ee5\u4fbf\u5f8c\u7e8c\u5206\u6790\u3002<\/li>\n<\/ul>\n<p>\u4ee5\u4e0b\u662f\u4e00\u500b\u793a\u4f8b\u4ee3\u78bc\uff0c\u5c55\u793a\u5982\u4f55\u6aa2\u67e5\u67e5\u8a62\u7d50\u679c\uff1a<\/p>\n<pre><code>\n$result = mysqli_query($conn, \"SELECT * FROM users WHERE id = 999\");\nif (mysqli_num_rows($result) &gt; 0) {\n    \/\/ \u8655\u7406\u67e5\u8a62\u7d50\u679c\n} else {\n    echo \"\u8a72\u7528\u6236\u4e0d\u5b58\u5728\u3002\";\n}\n<\/code><\/pre>\n<h2 id=\"3-%e4%bd%bf%e7%94%a8%e6%a2%9d%e4%bb%b6%e6%9f%a5%e8%a9%a2-sfZJlDTuKu\">3. \u4f7f\u7528\u689d\u4ef6\u67e5\u8a62<\/h2>\n<p>\u5728\u67d0\u4e9b\u60c5\u6cc1\u4e0b\uff0c\u958b\u767c\u8005\u53ef\u80fd\u5e0c\u671b\u5728\u67e5\u8a62\u4e2d\u4f7f\u7528\u689d\u4ef6\u4f86\u8655\u7406\u4e0d\u5b58\u5728\u7684\u8a18\u9304\u3002\u4f8b\u5982\uff0c\u53ef\u4ee5\u4f7f\u7528 LEFT JOIN \u4f86\u67e5\u8a62\u76f8\u95dc\u6578\u64da\uff0c\u5373\u4f7f\u4e3b\u8868\u4e2d\u7684\u8a18\u9304\u4e0d\u5b58\u5728\uff0c\u4e5f\u80fd\u8fd4\u56de\u7d50\u679c\u3002\u4ee5\u4e0b\u662f\u4e00\u500b\u793a\u4f8b\uff1a<\/p>\n<pre><code>\nSELECT users.name, orders.amount \nFROM users \nLEFT JOIN orders ON users.id = orders.user_id \nWHERE users.id = 999;\n<\/code><\/pre>\n<p>\u5728\u9019\u500b\u67e5\u8a62\u4e2d\uff0c\u5373\u4f7f\u7528\u6236 ID \u70ba 999 \u7684\u7528\u6236\u4e0d\u5b58\u5728\uff0c\u67e5\u8a62\u4ecd\u7136\u6703\u8fd4\u56de\u4e00\u884c\u7d50\u679c\uff0c\u986f\u793a\u7528\u6236\u540d\u7a31\u70ba NULL\uff0c\u8a02\u55ae\u91d1\u984d\u70ba NULL\u3002<\/p>\n<h2 id=\"4-%e9%8c%af%e8%aa%a4%e8%99%95%e7%90%86-sfZJlDTuKu\">4. \u932f\u8aa4\u8655\u7406<\/h2>\n<p>\u9664\u4e86\u6aa2\u67e5\u7a7a\u7d50\u679c\u96c6\u5916\uff0c\u958b\u767c\u8005\u9084\u61c9\u8a72\u8003\u616e\u5230\u5176\u4ed6\u53ef\u80fd\u7684\u932f\u8aa4\u60c5\u6cc1\uff0c\u4f8b\u5982\u6578\u64da\u5eab\u9023\u63a5\u5931\u6557\u6216\u67e5\u8a62\u8a9e\u6cd5\u932f\u8aa4\u3002\u4f7f\u7528 try-catch \u8a9e\u53e5\u53ef\u4ee5\u6709\u6548\u6355\u7372\u9019\u4e9b\u932f\u8aa4\u4e26\u9032\u884c\u8655\u7406\uff1a<\/p>\n<pre><code>\ntry {\n    $result = mysqli_query($conn, \"SELECT * FROM users WHERE id = 999\");\n    if (!$result) {\n        throw new Exception(\"\u67e5\u8a62\u5931\u6557: \" . mysqli_error($conn));\n    }\n} catch (Exception $e) {\n    echo \"\u932f\u8aa4: \" . $e-&gt;getMessage();\n}\n<\/code><\/pre>\n<h2 id=\"5-%e7%b8%bd%e7%b5%90-sfZJlDTuKu\">5. \u7e3d\u7d50<\/h2>\n<p>\u5728 MySQL \u6578\u64da\u5eab\u4e2d\uff0c\u7576\u67e5\u8a62\u7684\u8a18\u9304\u4e0d\u5b58\u5728\u6642\uff0c\u958b\u767c\u8005\u9700\u8981\u63a1\u53d6\u9069\u7576\u7684\u63aa\u65bd\u4f86\u8655\u7406\u7a7a\u7d50\u679c\u96c6\u548c\u6f5b\u5728\u7684\u932f\u8aa4\u3002\u901a\u904e\u6aa2\u67e5\u7d50\u679c\u96c6\u3001\u4f7f\u7528\u689d\u4ef6\u67e5\u8a62\u548c\u932f\u8aa4\u8655\u7406\uff0c\u958b\u767c\u8005\u53ef\u4ee5\u78ba\u4fdd\u61c9\u7528\u7a0b\u5e8f\u7684\u7a69\u5b9a\u6027\u548c\u7528\u6236\u9ad4\u9a57\u3002<\/p>\n<p>\u5982\u679c\u60a8\u6b63\u5728\u5c0b\u627e\u9ad8\u6548\u7684 <a href=\"https:\/\/server.hk\">VPS<\/a> \u89e3\u6c7a\u65b9\u6848\u4f86\u652f\u6301\u60a8\u7684\u6578\u64da\u5eab\u61c9\u7528\uff0cServer.HK \u63d0\u4f9b\u591a\u7a2e\u9078\u64c7\uff0c\u6eff\u8db3\u4e0d\u540c\u9700\u6c42\u3002\u7121\u8ad6\u662f <a href=\"https:\/\/server.hk\">\u9999\u6e2fVPS<\/a> \u9084\u662f\u5176\u4ed6\u670d\u52d9\uff0c\u6211\u5011\u90fd\u80fd\u70ba\u60a8\u63d0\u4f9b\u7a69\u5b9a\u7684\u652f\u6301\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4e86\u89e3\u5982\u4f55\u5728MySQL\u6578\u64da\u5eab\u4e2d\u8655\u7406\u4e0d\u5b58\u5728\u7684\u8a18\u9304\uff0c\u5305\u62ec\u67e5\u8a62\u3001\u932f\u8aa4\u8655\u7406\u548c\u66ff\u4ee3\u65b9\u6848\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-75634","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/75634","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=75634"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/75634\/revisions"}],"predecessor-version":[{"id":75635,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/75634\/revisions\/75635"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=75634"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=75634"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=75634"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}