{"id":589,"date":"2010-08-24T13:44:00","date_gmt":"2010-08-24T05:44:00","guid":{"rendered":"http:\/\/note.systw.net\/note\/?p=589"},"modified":"2023-11-04T13:44:47","modified_gmt":"2023-11-04T05:44:47","slug":"%e5%90%88%e4%bd%b5%e7%90%86%e8%ab%96","status":"publish","type":"post","link":"https:\/\/systw.net\/note\/archives\/589","title":{"rendered":"\u5408\u4f75\u7406\u8ad6"},"content":{"rendered":"\n

\u5408\u4f75\u7406\u8ad6<\/strong>
\u76ee\u7684:\u900f\u904ejoin(\u5408\u4f75)\u904e\u7a0b\u5f97\u5230\u4e00\u500b\u865b\u64ec\u95dc\u806f\u4f86\u9054\u5230\u67e5\u8a62\u4e0a\u7684\u65b9\u4fbf<\/p>\n\n\n\n

join\u6709\u4ee5\u4e0b\u5e7e\u7a2e
cross join(\u4ea4\u53c9\u5408\u4f75)<\/strong>
\u4e5f\u7a31cartesian product(\u5361\u6c0f\u7a4d)\u6216cross product(\u4ea4\u53c9\u4e58\u7a4d)
\u985e\u4f3c\u4e58\u6cd5\u7684\u6982\u5ff5
inner join(\u5167\u90e8\u5408\u4f75)\/condition join(\u689d\u4ef6\u5408\u4f75)<\/strong>
\u4f7f\u7528\u4ea4\u96c6\u7684\u6982\u5ff5,\u53ea\u6703\u5f9e\u5169table\u4e2d\u53d6\u51fa\u76f8\u540c\u7684\u90e8\u4efd
outer join(\u5916\u90e8\u5408\u4f75)<\/strong>
\u53ef\u5728\u5206\u70ba\u4ee5\u4e0b
\u3000left outer join,\u4ee5\u7b2c\u4e00\u500btable\u70ba\u6e96
\u3000right outer join,\u4ee5\u7b2c\u4e8c\u500btable\u70ba\u6e96
\u3000full outer join:\u5169table\u7684\u806f\u96c6
self-join(\u81ea\u6211\u5408\u4f75)<\/strong><\/p>\n\n\n\n

……………………………………………………<\/p>\n\n\n\n

\u4ee5\u90192\u8cc7\u6599\u8868\u70ba\u4f8b
(src_ip , dst_port , sig_id)<\/strong>
192.168.1.5 , 80 , 0
192.168.1.1 , 80 , 1
192.168.1.2 , 443 , 2
(sig_id , sig_name)<\/strong>
1 , sql_injection
2 , ddos
3 , backdoor
4 , shellcode<\/p>\n\n\n\n


inner join<\/strong>
\u51712\u7b46,\u7d50\u679c\u5982\u4e0b
(src_ip , dst_port , sig_id , sig_name)
192.168.1.1 , 80 , 1 , sql_injection
192.168.1.2 , 443 , 2 , ddos<\/p>\n\n\n\n

left outer join<\/strong>
\u51712(inner)+1(left)\u7b46,\u7d50\u679c\u5982\u4e0b
(src_ip , dst_port , sig_id , sig_name)
192.168.1.5 , 80 , 0 , null<\/strong>
192.168.1.1 , 80 , 1 , sql_injection
192.168.1.2 , 443 , 2 , ddos<\/p>\n\n\n\n

right outer join<\/strong>
\u51712(inner)+2(right)\u7b46,\u7d50\u679c\u5982\u4e0b
(src_ip , dst_port , sig_id , sig_name)
192.168.1.1 , 80 , 1 , sql_injection
192.168.1.2 , 443 , 2 , ddos
null , null , 3 , backdoor
null , null , 4 , shellcode<\/strong><\/p>\n\n\n\n

full join<\/strong>
\u51712(inner)+1(left)+2(right)\u7b46,\u7d50\u679c\u5982\u4e0b
(src_ip , dst_port , sig_id , sig_name)
192.168.1.5 , 80 , 0 , null<\/strong>
192.168.1.1 , 80 , 1 , sql_injection
192.168.1.2 , 443 , 2 , ddos
null , null , 3 , backdoor
null , null , 4 , shellcode<\/strong><\/p>\n","protected":false},"excerpt":{"rendered":"

\u5408\u4f75\u7406\u8ad6\u76ee\u7684:\u900f\u904ejoin(\u5408\u4f75)\u904e\u7a0b\u5f97\u5230\u4e00\u500b\u865b\u64ec\u95dc\u806f\u4f86\u9054\u5230 …<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"fifu_image_url":"","fifu_image_alt":"","_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[16],"tags":[],"class_list":["post-589","post","type-post","status-publish","format-standard","hentry","category-database"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/posts\/589","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/comments?post=589"}],"version-history":[{"count":0,"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/posts\/589\/revisions"}],"wp:attachment":[{"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/media?parent=589"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/categories?post=589"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/tags?post=589"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}