{"id":172827,"date":"2024-11-07T15:24:05","date_gmt":"2024-11-07T07:24:05","guid":{"rendered":"https:\/\/server.hk\/cnblog\/172827\/"},"modified":"2024-11-07T15:24:06","modified_gmt":"2024-11-07T07:24:06","slug":"%e5%a6%82%e4%bd%95%e6%9f%a5%e8%a9%a2%e6%95%b8%e6%93%9a%e5%ba%ab%e4%b8%ad%e6%9c%80%e6%96%b0%e7%9a%84%e4%b8%80%e6%a2%9d%e6%95%b8%e6%93%9a%ef%bc%9f-%e6%95%b8%e6%93%9a%e5%ba%ab%e6%9f%a5%e8%a9%a2%e8%a1%a8","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/172827\/","title":{"rendered":"\u5982\u4f55\u67e5\u8a62\u6578\u64da\u5eab\u4e2d\u6700\u65b0\u7684\u4e00\u689d\u6578\u64da\uff1f (\u6578\u64da\u5eab\u67e5\u8a62\u8868\u6700\u65b0\u4e00\u689d\u6578\u64da)"},"content":{"rendered":"

\u5982\u4f55\u67e5\u8a62\u6578\u64da\u5eab\u4e2d\u6700\u65b0\u7684\u4e00\u689d\u6578\u64da\uff1f<\/h1>\n

\u5728\u6578\u64da\u5eab\u7ba1\u7406\u4e2d\uff0c\u67e5\u8a62\u6700\u65b0\u7684\u4e00\u689d\u6578\u64da\u662f\u4e00\u500b\u5e38\u898b\u7684\u9700\u6c42\u3002\u7121\u8ad6\u662f\u7528\u65bc\u986f\u793a\u6700\u65b0\u7684\u7528\u6236\u6d3b\u52d5\u3001\u6700\u65b0\u7684\u8a02\u55ae\uff0c\u9084\u662f\u6700\u65b0\u7684\u6578\u64da\u66f4\u65b0\uff0c\u638c\u63e1\u5982\u4f55\u6709\u6548\u5730\u67e5\u8a62\u6700\u65b0\u6578\u64da\u5c0d\u65bc\u958b\u767c\u8005\u548c\u6578\u64da\u5206\u6790\u5e2b\u4f86\u8aaa\u90fd\u662f\u81f3\u95dc\u91cd\u8981\u7684\u3002\u672c\u6587\u5c07\u4ecb\u7d39\u5e7e\u7a2e\u5e38\u898b\u7684\u6578\u64da\u5eab\u67e5\u8a62\u65b9\u6cd5\uff0c\u5e6b\u52a9\u60a8\u5feb\u901f\u7372\u53d6\u6700\u65b0\u7684\u4e00\u689d\u6578\u64da\u3002<\/p>\n

\u4f7f\u7528 SQL \u67e5\u8a62\u6700\u65b0\u6578\u64da<\/h2>\n

\u5728\u5927\u591a\u6578\u95dc\u4fc2\u578b\u6578\u64da\u5eab\u4e2d\uff0c\u4f7f\u7528 SQL \u8a9e\u8a00\u4f86\u67e5\u8a62\u6578\u64da\u662f\u6700\u5e38\u898b\u7684\u65b9\u5f0f\u3002\u4ee5\u4e0b\u662f\u4e00\u4e9b\u5e38\u898b\u7684 SQL \u67e5\u8a62\u793a\u4f8b\uff0c\u9019\u4e9b\u67e5\u8a62\u53ef\u4ee5\u5e6b\u52a9\u60a8\u7372\u53d6\u6700\u65b0\u7684\u4e00\u689d\u6578\u64da\u3002<\/p>\n

1. \u4f7f\u7528 ORDER BY \u548c LIMIT<\/h3>\n

\u6700\u7c21\u55ae\u7684\u65b9\u6cd5\u662f\u4f7f\u7528 ORDER BY<\/code> \u5b50\u53e5\u4f86\u6839\u64da\u6642\u9593\u6233\u6216\u81ea\u589e ID \u6392\u5e8f\uff0c\u7136\u5f8c\u4f7f\u7528 LIMIT<\/code> \u9650\u5236\u7d50\u679c\u96c6\u7684\u5927\u5c0f\u3002\u4ee5\u4e0b\u662f\u4e00\u500b\u793a\u4f8b\uff1a<\/p>\n

SELECT * FROM orders\nORDER BY created_at DESC\nLIMIT 1;<\/code><\/pre>\n
\u5728\u9019\u500b\u67e5\u8a62\u4e2d\uff0ccreated_at<\/code> \u662f\u4e00\u500b\u6642\u9593\u6233\u5b57\u6bb5\uff0c\u8868\u793a\u8a02\u55ae\u7684\u5275\u5efa\u6642\u9593\u3002\u9019\u500b\u67e5\u8a62\u5c07\u8fd4\u56de\u6700\u65b0\u7684\u4e00\u689d\u8a02\u55ae\u6578\u64da\u3002<\/p>\n
2. \u4f7f\u7528\u5b50\u67e5\u8a62<\/h3>\n
\u53e6\u4e00\u7a2e\u65b9\u6cd5\u662f\u4f7f\u7528\u5b50\u67e5\u8a62\u4f86\u7372\u53d6\u6700\u65b0\u7684\u6578\u64da\u3002\u4f8b\u5982\uff0c\u60a8\u53ef\u4ee5\u5148\u67e5\u8a62\u6700\u5927\u6642\u9593\u6233\uff0c\u7136\u5f8c\u518d\u6839\u64da\u9019\u500b\u6642\u9593\u6233\u67e5\u8a62\u5177\u9ad4\u7684\u6578\u64da\uff1a<\/p>\n
SELECT * FROM orders\nWHERE created_at = (SELECT MAX(created_at) FROM orders);<\/code><\/pre>\n
\u9019\u500b\u67e5\u8a62\u5c07\u8fd4\u56de\u6240\u6709\u5728\u6700\u65b0\u6642\u9593\u6233\u4e0b\u7684\u8a02\u55ae\u6578\u64da\uff0c\u9019\u5728\u67d0\u4e9b\u60c5\u6cc1\u4e0b\u53ef\u80fd\u6703\u8fd4\u56de\u591a\u689d\u6578\u64da\u3002<\/p>\n
3. \u4f7f\u7528\u7a97\u53e3\u51fd\u6578<\/h3>\n
\u5982\u679c\u60a8\u7684\u6578\u64da\u5eab\u652f\u6301\u7a97\u53e3\u51fd\u6578\uff0c\u60a8\u53ef\u4ee5\u4f7f\u7528 ROW_NUMBER()<\/code> \u4f86\u6a19\u8a18\u6bcf\u4e00\u884c\u7684\u9806\u5e8f\uff0c\u7136\u5f8c\u9078\u64c7\u6700\u65b0\u7684\u4e00\u689d\u6578\u64da\uff1a<\/p>\n
SELECT * FROM (\n    SELECT *, ROW_NUMBER() OVER (ORDER BY created_at DESC) as rn\n    FROM orders\n) as subquery\nWHERE rn = 1;<\/code><\/pre>\n
\u9019\u7a2e\u65b9\u6cd5\u7684\u597d\u8655\u5728\u65bc\u5b83\u53ef\u4ee5\u8f15\u9b06\u64f4\u5c55\u5230\u66f4\u8907\u96dc\u7684\u67e5\u8a62\u4e2d\uff0c\u4e26\u4e14\u80fd\u5920\u8655\u7406\u591a\u689d\u6700\u65b0\u6578\u64da\u7684\u60c5\u6cc1\u3002<\/p>\n
\u8003\u616e\u6578\u64da\u5eab\u6027\u80fd<\/h2>\n
\u5728\u67e5\u8a62\u6700\u65b0\u6578\u64da\u6642\uff0c\u6027\u80fd\u662f\u4e00\u500b\u91cd\u8981\u7684\u8003\u91cf\u56e0\u7d20\u3002\u5c0d\u65bc\u5927\u578b\u6578\u64da\u96c6\uff0c\u4f7f\u7528\u7d22\u5f15\u53ef\u4ee5\u986f\u8457\u63d0\u9ad8\u67e5\u8a62\u901f\u5ea6\u3002\u78ba\u4fdd\u5728 created_at<\/code> \u6216\u5176\u4ed6\u7528\u65bc\u6392\u5e8f\u7684\u5b57\u6bb5\u4e0a\u5efa\u7acb\u7d22\u5f15\uff0c\u9019\u6a23\u53ef\u4ee5\u52a0\u5feb\u67e5\u8a62\u7684\u57f7\u884c\u901f\u5ea6\u3002<\/p>\n
\u7d50\u8ad6<\/h2>\n
\u67e5\u8a62\u6578\u64da\u5eab\u4e2d\u6700\u65b0\u7684\u4e00\u689d\u6578\u64da\u662f\u4e00\u9805\u57fa\u672c\u4f46\u91cd\u8981\u7684\u6280\u80fd\u3002\u7121\u8ad6\u60a8\u9078\u64c7\u4f7f\u7528 ORDER BY<\/code> \u548c LIMIT<\/code>\uff0c\u5b50\u67e5\u8a62\uff0c\u9084\u662f\u7a97\u53e3\u51fd\u6578\uff0c\u4e86\u89e3\u9019\u4e9b\u65b9\u6cd5\u5c07\u5e6b\u52a9\u60a8\u66f4\u6709\u6548\u5730\u7ba1\u7406\u548c\u5206\u6790\u6578\u64da\u3002\u96a8\u8457\u6578\u64da\u91cf\u7684\u589e\u9577\uff0c\u512a\u5316\u67e5\u8a62\u6027\u80fd\u4e5f\u8b8a\u5f97\u8d8a\u4f86\u8d8a\u91cd\u8981\u3002<\/p>\n
\u5982\u679c\u60a8\u6b63\u5728\u5c0b\u627e\u9ad8\u6548\u7684\u6578\u64da\u5eab\u89e3\u6c7a\u65b9\u6848\uff0c\u8003\u616e\u4f7f\u7528 \u9999\u6e2fVPS<\/a> \u4f86\u6258\u7ba1\u60a8\u7684\u61c9\u7528\u7a0b\u5e8f\u548c\u6578\u64da\u5eab\u3002\u7121\u8ad6\u662f\u9700\u8981\u9ad8\u6027\u80fd\u7684 \u4e91\u4f3a\u670d\u5668<\/a> \u9084\u662f\u7a69\u5b9a\u7684 \u9999\u6e2f\u4f3a\u670d\u5668<\/a>\uff0cServer.HK \u90fd\u80fd\u63d0\u4f9b\u53ef\u9760\u7684\u652f\u6301\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
\u4e86\u89e3\u5982\u4f55\u5728\u6578\u64da\u5eab\u4e2d\u67e5\u8a62\u6700\u65b0\u4e00\u689d\u6578\u64da\uff0c\u638c\u63e1\u6709\u6548\u7684SQL\u8a9e\u53e5\u548c\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-172827","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/172827","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=172827"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/172827\/revisions"}],"predecessor-version":[{"id":172828,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/172827\/revisions\/172828"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=172827"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=172827"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=172827"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}