{"id":172507,"date":"2024-11-07T13:42:21","date_gmt":"2024-11-07T05:42:21","guid":{"rendered":"https:\/\/server.hk\/cnblog\/172507\/"},"modified":"2024-11-07T13:42:21","modified_gmt":"2024-11-07T05:42:21","slug":"%e5%a6%82%e4%bd%95%e6%af%94%e5%b0%8d%e5%bc%95%e7%94%a8%e5%85%b6%e4%bb%96%e6%95%b8%e6%93%9a%e5%ba%ab%e7%9a%84%e5%85%a9%e5%88%97%e6%95%b8%e6%93%9a%ef%bc%9f-%e6%af%94%e5%b0%8d%e5%85%a9%e5%88%97%e6%95%b8","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/172507\/","title":{"rendered":"\u5982\u4f55\u6bd4\u5c0d\u5f15\u7528\u5176\u4ed6\u6578\u64da\u5eab\u7684\u5169\u5217\u6578\u64da\uff1f (\u6bd4\u5c0d\u5169\u5217\u6578\u64da\u5f15\u7528\u53e6\u4e00\u5217\u6578\u64da\u5eab)"},"content":{"rendered":"

\u5982\u4f55\u6bd4\u5c0d\u5f15\u7528\u5176\u4ed6\u6578\u64da\u5eab\u7684\u5169\u5217\u6578\u64da\uff1f<\/h1>\n

\u5728\u6578\u64da\u5206\u6790\u548c\u6578\u64da\u5eab\u7ba1\u7406\u4e2d\uff0c\u6bd4\u5c0d\u4e0d\u540c\u6578\u64da\u5eab\u4e2d\u7684\u6578\u64da\u662f\u4e00\u9805\u5e38\u898b\u7684\u4efb\u52d9\u3002\u5c24\u5176\u662f\u5728\u9700\u8981\u5f9e\u591a\u500b\u6578\u64da\u6e90\u4e2d\u63d0\u53d6\u4fe1\u606f\u6642\uff0c\u80fd\u5920\u6709\u6548\u5730\u6bd4\u5c0d\u5169\u5217\u6578\u64da\u662f\u81f3\u95dc\u91cd\u8981\u7684\u3002\u672c\u6587\u5c07\u63a2\u8a0e\u5982\u4f55\u6bd4\u5c0d\u5f15\u7528\u5176\u4ed6\u6578\u64da\u5eab\u7684\u5169\u5217\u6578\u64da\uff0c\u4e26\u63d0\u4f9b\u4e00\u4e9b\u5be6\u7528\u7684\u793a\u4f8b\u548c\u4ee3\u78bc\u7247\u6bb5\u3002<\/p>\n

\u6bd4\u5c0d\u6578\u64da\u7684\u57fa\u672c\u6982\u5ff5<\/h2>\n

\u6bd4\u5c0d\u6578\u64da\u901a\u5e38\u6d89\u53ca\u5230\u5f9e\u4e00\u500b\u6578\u64da\u5eab\u4e2d\u63d0\u53d6\u7279\u5b9a\u5217\u7684\u6578\u64da\uff0c\u7136\u5f8c\u5c07\u5176\u8207\u53e6\u4e00\u500b\u6578\u64da\u5eab\u4e2d\u7684\u5217\u9032\u884c\u6bd4\u8f03\u3002\u9019\u4e00\u904e\u7a0b\u53ef\u4ee5\u5e6b\u52a9\u6211\u5011\u8b58\u5225\u6578\u64da\u4e4b\u9593\u7684\u76f8\u4f3c\u6027\u548c\u5dee\u7570\u6027\uff0c\u4e26\u9032\u4e00\u6b65\u9032\u884c\u6578\u64da\u6e05\u7406\u6216\u6578\u64da\u6574\u5408\u3002<\/p>\n

\u4f7f\u7528 SQL \u9032\u884c\u6578\u64da\u6bd4\u5c0d<\/h2>\n

\u5728\u5927\u591a\u6578\u60c5\u6cc1\u4e0b\uff0c\u4f7f\u7528 SQL \u8a9e\u8a00\u4f86\u6bd4\u5c0d\u6578\u64da\u662f\u6700\u6709\u6548\u7684\u65b9\u6cd5\u3002\u4ee5\u4e0b\u662f\u4e00\u4e9b\u5e38\u898b\u7684 SQL \u67e5\u8a62\u793a\u4f8b\uff0c\u9019\u4e9b\u67e5\u8a62\u53ef\u4ee5\u5e6b\u52a9\u6211\u5011\u6bd4\u5c0d\u5169\u5217\u6578\u64da\u3002<\/p>\n

\u793a\u4f8b 1\uff1a\u4f7f\u7528 INNER JOIN<\/h3>\n

\u5047\u8a2d\u6211\u5011\u6709\u5169\u500b\u6578\u64da\u8868\uff1atable_a<\/code> \u548c table_b<\/code>\uff0c\u6211\u5011\u60f3\u8981\u6bd4\u5c0d\u9019\u5169\u500b\u8868\u4e2d\u7684 column1<\/code> \u548c column2<\/code>\u3002<\/p>\n

SELECT a.column1, b.column2\nFROM table_a a\nINNER JOIN table_b b ON a.column1 = b.column2;<\/code><\/pre>\n
\u9019\u500b\u67e5\u8a62\u5c07\u8fd4\u56de\u5728 table_a<\/code> \u7684 column1<\/code> \u548c table_b<\/code> \u7684 column2<\/code> \u4e2d\u76f8\u5339\u914d\u7684\u6240\u6709\u884c\u3002<\/p>\n
\u793a\u4f8b 2\uff1a\u4f7f\u7528 LEFT JOIN<\/h3>\n
\u5982\u679c\u6211\u5011\u5e0c\u671b\u4fdd\u7559 table_a<\/code> \u4e2d\u7684\u6240\u6709\u884c\uff0c\u5373\u4f7f\u5728 table_b<\/code> \u4e2d\u6c92\u6709\u5339\u914d\u7684\u884c\uff0c\u6211\u5011\u53ef\u4ee5\u4f7f\u7528 LEFT JOIN\u3002<\/p>\n
SELECT a.column1, b.column2\nFROM table_a a\nLEFT JOIN table_b b ON a.column1 = b.column2;<\/code><\/pre>\n
\u9019\u6a23\u7684\u67e5\u8a62\u5c07\u8fd4\u56de table_a<\/code> \u4e2d\u7684\u6240\u6709\u884c\uff0c\u4e26\u5728 table_b<\/code> \u4e2d\u627e\u4e0d\u5230\u5339\u914d\u7684\u884c\u6642\u8fd4\u56de NULL\u3002<\/p>\n
\u4f7f\u7528 Python \u9032\u884c\u6578\u64da\u6bd4\u5c0d<\/h2>\n
\u9664\u4e86 SQL\uff0c\u4f7f\u7528 Python \u9032\u884c\u6578\u64da\u6bd4\u5c0d\u4e5f\u662f\u4e00\u500b\u6d41\u884c\u7684\u9078\u64c7\u3002\u7279\u5225\u662f\u7576\u6578\u64da\u91cf\u8f03\u5927\u6216\u9700\u8981\u9032\u884c\u66f4\u8907\u96dc\u7684\u6578\u64da\u8655\u7406\u6642\uff0cPython \u7684\u6578\u64da\u5206\u6790\u5eab\uff08\u5982 Pandas\uff09\u53ef\u4ee5\u63d0\u4f9b\u5f37\u5927\u7684\u652f\u6301\u3002<\/p>\n
\u793a\u4f8b\uff1a\u4f7f\u7528 Pandas \u9032\u884c\u6bd4\u5c0d<\/h3>\n
import pandas as pd\n\n# \u8b80\u53d6\u6578\u64da\ntable_a = pd.read_csv('table_a.csv')\ntable_b = pd.read_csv('table_b.csv')\n\n# \u6bd4\u5c0d\u5169\u5217\nmerged = pd.merge(table_a, table_b, left_on='column1', right_on='column2', how='inner')\n\nprint(merged)<\/code><\/pre>\n
\u5728\u9019\u500b\u793a\u4f8b\u4e2d\uff0c\u6211\u5011\u4f7f\u7528 Pandas \u7684 merge<\/code> \u51fd\u6578\u4f86\u6bd4\u5c0d\u5169\u500b\u6578\u64da\u6846\u4e2d\u7684\u5217\u3002\u9019\u7a2e\u65b9\u6cd5\u4e0d\u50c5\u7c21\u55ae\uff0c\u800c\u4e14\u53ef\u4ee5\u8f15\u9b06\u8655\u7406\u5927\u578b\u6578\u64da\u96c6\u3002<\/p>\n
\u7d50\u8ad6<\/h2>\n
\u6bd4\u5c0d\u5f15\u7528\u5176\u4ed6\u6578\u64da\u5eab\u7684\u5169\u5217\u6578\u64da\u662f\u4e00\u9805\u91cd\u8981\u7684\u6578\u64da\u8655\u7406\u4efb\u52d9\uff0c\u7121\u8ad6\u662f\u4f7f\u7528 SQL \u9084\u662f Python\uff0c\u90fd\u53ef\u4ee5\u6709\u6548\u5730\u5b8c\u6210\u9019\u4e00\u4efb\u52d9\u3002\u901a\u904e\u9069\u7576\u7684\u67e5\u8a62\u548c\u4ee3\u78bc\uff0c\u6211\u5011\u53ef\u4ee5\u8f15\u9b06\u8b58\u5225\u6578\u64da\u4e4b\u9593\u7684\u95dc\u4fc2\uff0c\u5f9e\u800c\u9032\u884c\u66f4\u6df1\u5165\u7684\u5206\u6790\u548c\u6c7a\u7b56\u3002<\/p>\n
\u5982\u679c\u60a8\u9700\u8981\u9ad8\u6548\u7684\u6578\u64da\u8655\u7406\u548c\u5b58\u5132\u89e3\u6c7a\u65b9\u6848\uff0c\u8003\u616e\u4f7f\u7528 \u9999\u6e2fVPS<\/a> \u670d\u52d9\uff0c\u9019\u5c07\u70ba\u60a8\u7684\u6578\u64da\u5206\u6790\u63d0\u4f9b\u7a69\u5b9a\u7684\u652f\u6301\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
\u5b78\u7fd2\u5982\u4f55\u6709\u6548\u6bd4\u5c0d\u5169\u5217\u6578\u64da\uff0c\u4e26\u5f15\u7528\u5176\u4ed6\u6578\u64da\u5eab\u7684\u8cc7\u6599\uff0c\u63d0\u5347\u6578\u64da\u5206\u6790\u7684\u6e96\u78ba\u6027\u8207\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-172507","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/172507","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=172507"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/172507\/revisions"}],"predecessor-version":[{"id":172508,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/172507\/revisions\/172508"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=172507"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=172507"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=172507"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}