{"id":143743,"date":"2024-11-01T00:52:20","date_gmt":"2024-10-31T16:52:20","guid":{"rendered":"https:\/\/server.hk\/cnblog\/143743\/"},"modified":"2024-11-01T00:52:21","modified_gmt":"2024-10-31T16:52:21","slug":"sql-%e6%9f%a5%e8%a9%a2%ef%bc%9a%e5%a6%82%e4%bd%95%e5%9c%a8%e6%95%b8%e6%93%9a%e5%ba%ab%e4%b8%ad%e6%9f%a5%e8%a9%a2%e5%85%a9%e5%80%8b%e8%a1%a8%e7%9b%b8%e5%90%8c%e5%ad%97%e6%ae%b5%e7%9a%84%e6%95%b8","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/143743\/","title":{"rendered":"SQL \u67e5\u8a62\uff1a\u5982\u4f55\u5728\u6578\u64da\u5eab\u4e2d\u67e5\u8a62\u5169\u500b\u8868\u76f8\u540c\u5b57\u6bb5\u7684\u6578\u64da\uff1f\uff08\u6578\u64da\u5eab\u4e2d\u67e5\u8a62\u5169\u500b\u8868\u76f8\u540c\u5b57\u6bb5\u7684\u6578\u64da\u5eab\uff09"},"content":{"rendered":"

SQL \u67e5\u8a62\uff1a\u5982\u4f55\u5728\u6578\u64da\u5eab\u4e2d\u67e5\u8a62\u5169\u500b\u8868\u76f8\u540c\u5b57\u6bb5\u7684\u6578\u64da\uff1f<\/h1>\n

\u5728\u6578\u64da\u5eab\u7ba1\u7406\u4e2d\uff0c\u67e5\u8a62\u5169\u500b\u8868\u4e2d\u76f8\u540c\u5b57\u6bb5\u7684\u6578\u64da\u662f\u4e00\u500b\u5e38\u898b\u7684\u9700\u6c42\u3002\u9019\u7a2e\u67e5\u8a62\u901a\u5e38\u6d89\u53ca\u5230\u4f7f\u7528 SQL \u8a9e\u8a00\u4e2d\u7684 JOIN \u64cd\u4f5c\uff0c\u7279\u5225\u662f INNER JOIN \u548c LEFT JOIN\u3002\u672c\u6587\u5c07\u6df1\u5165\u63a2\u8a0e\u5982\u4f55\u4f7f\u7528\u9019\u4e9b SQL \u67e5\u8a62\u4f86\u7372\u53d6\u6240\u9700\u7684\u6578\u64da\uff0c\u4e26\u63d0\u4f9b\u5be6\u969b\u7684\u7bc4\u4f8b\u4f86\u5e6b\u52a9\u7406\u89e3\u3002<\/p>\n

\u57fa\u672c\u6982\u5ff5<\/h2>\n

\u5728 SQL \u4e2d\uff0c\u8868\u662f\u6578\u64da\u7684\u96c6\u5408\uff0c\u800c\u5b57\u6bb5\u5247\u662f\u8868\u4e2d\u7684\u5217\u3002\u7576\u6211\u5011\u9700\u8981\u5f9e\u5169\u500b\u8868\u4e2d\u67e5\u8a62\u76f8\u540c\u5b57\u6bb5\u7684\u6578\u64da\u6642\uff0c\u9996\u5148\u9700\u8981\u78ba\u5b9a\u9019\u5169\u500b\u8868\u4e4b\u9593\u7684\u95dc\u4fc2\u3002\u901a\u5e38\uff0c\u9019\u4e9b\u8868\u6703\u901a\u904e\u67d0\u500b\u5171\u540c\u7684\u5b57\u6bb5\uff08\u4f8b\u5982 ID\uff09\u4f86\u95dc\u806f\u3002<\/p>\n

\u4f7f\u7528 INNER JOIN \u67e5\u8a62\u76f8\u540c\u5b57\u6bb5\u7684\u6578\u64da<\/h2>\n

INNER JOIN \u662f\u6700\u5e38\u7528\u7684 JOIN \u985e\u578b\u4e4b\u4e00\u3002\u5b83\u6703\u8fd4\u56de\u5169\u500b\u8868\u4e2d\u5339\u914d\u7684\u884c\u3002\u4ee5\u4e0b\u662f\u4e00\u500b\u4f7f\u7528 INNER JOIN \u7684\u7bc4\u4f8b\uff1a<\/p>\n

SELECT a.id, a.name, b.salary\nFROM employees a\nINNER JOIN salaries b ON a.id = b.employee_id;<\/code><\/pre>\n
\u5728\u9019\u500b\u7bc4\u4f8b\u4e2d\uff0c\u6211\u5011\u6709\u5169\u500b\u8868\uff1aemployees<\/strong> \u548c salaries<\/strong>\u3002\u6211\u5011\u5e0c\u671b\u67e5\u8a62\u6bcf\u4f4d\u54e1\u5de5\u7684\u59d3\u540d\u53ca\u5176\u85aa\u6c34\u3002\u9019\u88e1\uff0ca.id<\/strong> \u548c b.employee_id<\/strong> \u662f\u6211\u5011\u7528\u4f86\u95dc\u806f\u9019\u5169\u500b\u8868\u7684\u5b57\u6bb5\u3002<\/p>\n
\u4f7f\u7528 LEFT JOIN \u67e5\u8a62\u76f8\u540c\u5b57\u6bb5\u7684\u6578\u64da<\/h2>\n
LEFT JOIN \u6703\u8fd4\u56de\u5de6\u5074\u8868\u7684\u6240\u6709\u884c\uff0c\u5373\u4f7f\u53f3\u5074\u8868\u4e2d\u6c92\u6709\u5339\u914d\u7684\u884c\u3002\u9019\u5728\u9700\u8981\u4fdd\u7559\u5de6\u5074\u8868\u7684\u6240\u6709\u6578\u64da\u6642\u975e\u5e38\u6709\u7528\u3002\u4ee5\u4e0b\u662f\u4f7f\u7528 LEFT JOIN \u7684\u7bc4\u4f8b\uff1a<\/p>\n
SELECT a.id, a.name, b.salary\nFROM employees a\nLEFT JOIN salaries b ON a.id = b.employee_id;<\/code><\/pre>\n
\u5728\u9019\u500b\u67e5\u8a62\u4e2d\uff0c\u5373\u4f7f\u67d0\u4e9b\u54e1\u5de5\u5728 salaries<\/strong> \u8868\u4e2d\u6c92\u6709\u5c0d\u61c9\u7684\u85aa\u6c34\u8a18\u9304\uff0c\u9019\u4e9b\u54e1\u5de5\u7684\u59d3\u540d\u4ecd\u7136\u6703\u88ab\u5217\u51fa\uff0c\u85aa\u6c34\u5247\u6703\u986f\u793a\u70ba NULL\u3002<\/p>\n
\u67e5\u8a62\u591a\u500b\u76f8\u540c\u5b57\u6bb5<\/h2>\n
\u5982\u679c\u9700\u8981\u67e5\u8a62\u591a\u500b\u76f8\u540c\u5b57\u6bb5\uff0c\u53ef\u4ee5\u5728 SELECT \u8a9e\u53e5\u4e2d\u5217\u51fa\u9019\u4e9b\u5b57\u6bb5\u3002\u4f8b\u5982\uff1a<\/p>\n
SELECT a.id, a.name, b.salary, b.bonus\nFROM employees a\nINNER JOIN salaries b ON a.id = b.employee_id;<\/code><\/pre>\n
\u9019\u6a23\u7684\u67e5\u8a62\u5c07\u8fd4\u56de\u6bcf\u4f4d\u54e1\u5de5\u7684\u59d3\u540d\u3001\u85aa\u6c34\u548c\u734e\u91d1\uff0c\u524d\u63d0\u662f\u9019\u4e9b\u6578\u64da\u5728\u5169\u500b\u8868\u4e2d\u90fd\u6709\u5c0d\u61c9\u7684\u8a18\u9304\u3002<\/p>\n
\u4f7f\u7528 WHERE \u5b50\u53e5\u9032\u884c\u904e\u6ffe<\/h2>\n
\u5728\u67e5\u8a62\u4e2d\u4f7f\u7528 WHERE \u5b50\u53e5\u53ef\u4ee5\u9032\u4e00\u6b65\u904e\u6ffe\u7d50\u679c\u3002\u4f8b\u5982\uff0c\u5982\u679c\u6211\u5011\u53ea\u60f3\u67e5\u8a62\u85aa\u6c34\u9ad8\u65bc 50000 \u7684\u54e1\u5de5\uff0c\u53ef\u4ee5\u9019\u6a23\u5beb\uff1a<\/p>\n
SELECT a.id, a.name, b.salary\nFROM employees a\nINNER JOIN salaries b ON a.id = b.employee_id\nWHERE b.salary > 50000;<\/code><\/pre>\n
\u9019\u6a23\u7684\u67e5\u8a62\u5c07\u53ea\u8fd4\u56de\u85aa\u6c34\u9ad8\u65bc 50000 \u7684\u54e1\u5de5\u7684\u59d3\u540d\u548c\u85aa\u6c34\u3002<\/p>\n
\u7e3d\u7d50<\/h2>\n
\u5728 SQL \u4e2d\u67e5\u8a62\u5169\u500b\u8868\u76f8\u540c\u5b57\u6bb5\u7684\u6578\u64da\u662f\u4e00\u500b\u91cd\u8981\u7684\u6280\u80fd\uff0c\u7121\u8ad6\u662f\u4f7f\u7528 INNER JOIN \u9084\u662f LEFT JOIN\uff0c\u90fd\u80fd\u6709\u6548\u5730\u7372\u53d6\u6240\u9700\u7684\u4fe1\u606f\u3002\u901a\u904e\u9069\u7576\u7684\u67e5\u8a62\u8a9e\u53e5\u548c\u904e\u6ffe\u689d\u4ef6\uff0c\u60a8\u53ef\u4ee5\u9748\u6d3b\u5730\u5f9e\u6578\u64da\u5eab\u4e2d\u63d0\u53d6\u6709\u50f9\u503c\u7684\u6578\u64da\u3002<\/p>\n
\u5982\u679c\u60a8\u6b63\u5728\u5c0b\u627e\u9ad8\u6548\u7684 VPS<\/a> \u89e3\u6c7a\u65b9\u6848\u4f86\u652f\u6301\u60a8\u7684\u6578\u64da\u5eab\u64cd\u4f5c\uff0cServer.HK \u63d0\u4f9b\u591a\u7a2e\u9078\u64c7\uff0c\u6eff\u8db3\u4e0d\u540c\u9700\u6c42\u7684\u5ba2\u6236\u3002\u7121\u8ad6\u662f \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":"
\u5b78\u7fd2\u5982\u4f55\u5728\u6578\u64da\u5eab\u4e2d\u4f7f\u7528 SQL \u67e5\u8a62\u5169\u500b\u8868\u4e2d\u76f8\u540c\u5b57\u6bb5\u7684\u6578\u64da\uff0c\u63d0\u5347\u6578\u64da\u5206\u6790\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-143743","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/143743","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=143743"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/143743\/revisions"}],"predecessor-version":[{"id":143744,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/143743\/revisions\/143744"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=143743"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=143743"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=143743"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}