{"id":1725,"date":"2010-06-07T23:09:58","date_gmt":"2010-06-07T15:09:58","guid":{"rendered":"\/?p=1725"},"modified":"2010-06-07T23:09:58","modified_gmt":"2010-06-07T15:09:58","slug":"1725","status":"publish","type":"post","link":"https:\/\/www.justzz.com\/spec\/1725.html","title":{"rendered":"Hibernate\u4e32\u8bb2\u7b14\u8bb0\u4e09"},"content":{"rendered":"<p><strong>\u4e94\u3001\u5bf9\u8c61\u5728Hibernate\u4e2d\u7684\u72b6\u6001<\/strong><\/p>\n<p>\u5bf9\u8c61\u5728Hibernate\u4e2d\u7684\u72b6\u6001\u56fe\uff1a<\/p>\n<p>\u5bf9\u8c613\u79cd\u72b6\u6001\uff1a\u00a0 Transient(\u77ac\u65f6\/\u4e34\u65f6)\u00a0\u00a0 Persistent(\u6301\u4e45)\u00a0 Detached(\u8131\u7ba1\/\u6e38\u79bb)<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-7701\" src=\"https:\/\/www.justzz.com\/spec\/wp-content\/uploads\/sites\/3\/2019\/10\/201067-23818343.jpg\" width=\"505\" height=\"275\" alt=\"201067-23818343\" srcset=\"https:\/\/www.justzz.com\/spec\/files\/2019\/10\/201067-23818343.jpg 505w, https:\/\/www.justzz.com\/spec\/files\/2019\/10\/201067-23818343-300x163.jpg 300w\" sizes=\"auto, (max-width: 505px) 100vw, 505px\" \/><\/p>\n<p><strong>\u77ac\u65f6\u72b6\u6001<\/strong>(Transient)\uff1a<\/p>\n<p>\u5728\u5185\u5b58\u4e2d\u521a\u521a\u521b\u5efa\u7684\u5bf9\u8c61\uff0c\u8fd8\u6ca1\u6709\u540c\u6b65\u5230\u6570\u636e\u5e93\uff0c\u5982\u679c\u6ca1\u6709\u53d8\u91cf\u5bf9\u5b83\u8fdb\u884c\u5f15\u7528\uff0c\u5b83\u5c06\u88abJVM\u56de\u6536\u3002\u6216\u8005\u662f\u6570\u636e\u5e93\u4e2d\u4fe1\u606f\u88ab\u5220\u9664\u4e86\u7684\u5bf9\u8c61\u4e5f\u662f\u4e34\u65f6\u72b6\u6001\u3002<\/p>\n<p>\u7279\u70b9-- \u4e0d\u548cSession\u5b9e\u4f8b\u5173\u8054\uff1b<\/p>\n<p>\u5728\u6570\u636e\u5e93\u4e2d\u6ca1\u6709\u548c\u77ac\u65f6\u5bf9\u8c61\u5173\u8054\u7684\u8bb0\u5f55\u3002<\/p>\n<p><strong>\u6301\u4e45\u5316\u72b6\u6001<\/strong>(Persistent)\uff1a<\/p>\n<p>\u6301\u4e45\u7684\u5b9e\u4f8b\u5728\u6570\u636e\u5e93\u4e2d\u6709\u5bf9\u5e94\u7684\u8bb0\u5f55\uff0c\u5e76\u62e5\u6709\u4e00\u4e2a\u6301\u4e45\u5316\u6807\u8bc6\uff08identifier\uff09\u3002\u6301\u4e45\u7684\u4e8b\u4f8b\u53ef\u80fd\u662f\u521a\u88ab\u4fdd\u5b58\u7684\uff0c\u6216\u521a\u88ab\u52a0\u8f7d\u7684\uff0c\u65e0\u8bba\u54ea\u4e00\u79cd\uff0c\u6309\u5b9a\u4e49\u5bf9\u8c61\u90fd\u4ec5\u5728\u76f8\u5173\u8054\u7684Session\u751f\u547d\u5468\u671f\u5185\u4fdd\u6301\u8fd9\u79cd\u72b6\u6001\u3002\u800c\u4e14\u6301\u4e45\u5bf9\u8c61\u4e5f\u4e0eTransaction\u76f8\u5173\u8054\uff0c\u5fc5\u987b\u5728Transaction\u7ec8\u6b62\uff0c\u4e5f\u5c31\u662f\u6267\u884ccommit()\u4e4b\u540e\uff0c\u6301\u4e45\u5bf9\u8c61\u7684\u72b6\u6001\u624d\u4f1a\u4e0e\u6570\u636e\u5e93\u8fdb\u884c\u540c\u6b65\u3002<\/p>\n<p>\u7279\u70b9-- \u548cSession\u5b9e\u4f8b\u5173\u8054\uff1b<\/p>\n<p>\u5728\u6570\u636e\u5e93\u4e2d\u6709\u548c\u6301\u4e45\u5bf9\u8c61\u5173\u8054\u7684\u8bb0\u5f55\u3002<\/p>\n<p><strong>\u6e38\u79bb\u72b6\u6001<\/strong>(Detached)\uff1a<\/p>\n<p>\u4e0e\u6301\u4e45\u5bf9\u8c61\u5173\u8054\u7684Session\u88ab\u5173\u95ed\u540e\uff0c\u5bf9\u8c61\u5c31\u53d8\u4e3a\u6e38\u79bb\u7684\u3002\u5bf9\u6e38\u79bb\u5bf9\u8c61\u7684\u5f15\u7528\u4f9d\u7136\u6709\u6548\uff0c\u5bf9\u8c61\u53ef\u4ee5\u88ab\u7ee7\u7eed\u4fee\u6539\u3002\u6e38\u79bb\u5bf9\u8c61\u5982\u679c\u91cd\u65b0\u5173\u8054\u5230\u67d0\u4e2a\u65b0\u7684Session\u4e0a\uff0c\u4f1a\u518d\u6b21\u8f6c\u53d8\u4e3a\u6301\u4e45\u7684\uff08\u6ce8\uff1a\u8fd9\u6837\u6e38\u79bb\u72b6\u6001\u671f\u95f4\u7684\u6539\u52a8\u4f1a\u6301\u4e45\u5316\u5230\u6570\u636e\u5e93\u4e2d\uff09\u3002<\/p>\n<p>\u7279\u70b9-- \u672c\u8d28\u4e0a\u548c\u77ac\u65f6\u5bf9\u8c61\u76f8\u540c<\/p>\n<p>\u53ea\u662f\u6bd4\u77ac\u65f6\u5bf9\u8c61\u591a\u4e86\u4e00\u4e2a\u6570\u636e\u5e93\u8bb0\u5f55\u6807\u8bc6\u503cid<\/p>\n<p><strong>\u516d\u3001HQL<\/strong>(Hibernate Query Language)<\/p>\n<p>HQL\u662f\u9762\u5411\u5bf9\u8c61\u7684\u67e5\u8be2\u8bed\u8a00\uff0c\u5b83\u7684\u8bed\u6cd5\u548cSQL\u6709\u4e9b\u76f8\u4f3c\uff0c\u5728\u8fd0\u884c\u65f6\u624d\u5f97\u4ee5\u89e3\u6790\u3002<\/p>\n<p>\u6ce8\u610f\uff1aHQL\u662f\u9762\u5411\u5bf9\u8c61\u7684\uff0c\u4e0d\u8981\u5728\u8bed\u53e5\u4e2d\u6709\u8868\u7684\u6982\u5ff5\u5b58\u5728\u3002<\/p>\n<p><strong>1\uff0e\u6700\u7b80\u5355\u7684\u67e5\u8be2\uff1a<\/strong><\/p>\n<p>\u67e5\u8be2\u6240\u6709\u7684Student\u5bf9\u8c61\uff1a\u00a0\u00a0\u00a0 from Student\u00a0\u00a0 \u6216\u00a0\u00a0 select s from Student s<br \/>\n\u9664\u4e86Java\u7c7b\u4e0e\u5c5e\u6027\u540d\u79f0\u5916\uff0c\u67e5\u8be2\u8bed\u53e5\u5927\u5c0f\u5199\u4e0d\u654f\u611f\u3002<\/p>\n<p><strong>2\uff0e\u5c5e\u6027\u67e5\u8be2\uff1a<\/strong><\/p>\n<p>\u6709\u65f6\u4e0d\u5e0c\u671b\u5f97\u5230\u5bf9\u8c61\u6240\u6709\u5c5e\u6027\uff0c\u5219\uff1a<\/p>\n<p><strong>Q<\/strong>uery query = session.createQuery(\u201cselect s.name from Student s\u201d);<br \/>\nList list = query.list();<br \/>\nfor(int i=0; i&lt;list.size(); i++)<br \/>\n{<br \/>\nString name = (String)list.get(i);<br \/>\nSystem.out.println(name);<br \/>\n}<\/p>\n<p>\u82e5 \u201cselect s.name, s.age from Student as s\u201d\u00a0 \u5219\u67e5\u8be2\u7ed3\u679c\u4f1a\u4ee5\u6570\u7ec4\u5f62\u5f0f\u8fd4\u56de\u3002<\/p>\n<p>Object obj[] = (Object[]) list.get(i);<\/p>\n<p><strong>3\uff0e\u5b9e\u4f8b\u5316\u67e5\u8be2<\/strong><\/p>\n<p>\u662f\u5bf9\u5c5e\u6027\u67e5\u8be2\u7684\u4e00\u79cd\u6539\u8fdb\u3002\u5c06Object[]\u4e2d\u7684\u6240\u6709\u6210\u5458\u5c01\u88c5\u6210\u4e00\u4e2a\u5bf9\u8c61\uff1a<\/p>\n<p><strong>Q<\/strong>uery query = session.createQuery(\u201cselect new Student(s.name, s.age) from Student s\u201d)<br \/>\nList list = query.list();<br \/>\nfor(int i=0; i&lt;list.size(); i++)<br \/>\n{<br \/>\nStudent stu = (Student)list.get(i);\u00a0\u00a0 \/\/\u6b64Student\u5b9e\u4f8b\u5e76\u672a\u4e0e\u6570\u636e\u5e93\u6709\u4efb\u4f55\u5173\u7cfb<br \/>\nSystem.out.println(stu.getName());<br \/>\n}<\/p>\n<p><strong>4\uff0e\u8fde\u63a5\u67e5\u8be2<\/strong><\/p>\n<ul>\n<li>inner join (\u5185\u8fde\u63a5)<br \/>\nleft outer join (\u5de6\u5916\u8fde\u63a5)<br \/>\nright outer join (\u53f3\u5916\u8fde\u63a5)<br \/>\nfull join (\u5168\u8fde\u63a5\uff0c\u4e0d\u5e38\u7528)<\/li>\n<\/ul>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-7702\" src=\"https:\/\/www.justzz.com\/spec\/wp-content\/uploads\/sites\/3\/2019\/10\/201067-23930250.jpg\" width=\"342\" height=\"120\" alt=\"201067-23930250\" srcset=\"https:\/\/www.justzz.com\/spec\/files\/2019\/10\/201067-23930250.jpg 342w, https:\/\/www.justzz.com\/spec\/files\/2019\/10\/201067-23930250-300x105.jpg 300w\" sizes=\"auto, (max-width: 342px) 100vw, 342px\" \/><\/p>\n<p><strong>5\uff0e\u7edf\u8ba1\u51fd\u6570\u67e5\u8be2<\/strong><\/p>\n<p>\u5e38\u7528\uff1a count() \u3001 min() \u3001 max() \u3001 sum() \u3001 avg()<\/p>\n<p><strong>Q<\/strong>uery query = session.createQuery(\u201cselect count(*) from Student\u201d);\u00a0 \/\/\u53d6\u5f97Student\u6570\u91cf<br \/>\nQuery query = session createQuery(\u201cselect avg(s.age) from Student as s\u201d);<br \/>\n\/\/\u53d6\u5f97Student\u5e73\u5747\u5e74\u9f84<br \/>\nQuery query = session createQuery(\u201cselect upper(s.name) from Student as s\u201d);\u00a0 \/\/\u8f6c\u5927\u5199<br \/>\nQuery query = session createQuery(\u201cselect distinct s.age from Student as s\u201d); \/\/\u53bb\u9664\u91cd\u590d\u6570\u636e<\/p>\n<p><strong>6\uff0e\u5b50\u67e5\u8be2<\/strong><\/p>\n<p>\u5982\u679c\u5b50\u67e5\u8be2\u8fd4\u56de\u591a\u6761\u8bb0\u5f55\uff0c\u53ef\u4ee5\u7528\u4ee5\u4e0b\u5173\u952e\u5b57\u6765\u91cf\u5316\uff1a<br \/>\nall:\u00a0\u00a0 \u8868\u793a\u6240\u6709\u7684\u8bb0\u5f55<br \/>\nany:\u00a0 \u8868\u793a\u6240\u6709\u8bb0\u5f55\u4e2d\u7684\u4efb\u610f\u4e00\u6761<br \/>\nsome\u00a0 \u4e0eany\u7528\u6cd5\u4e00\u6837<br \/>\nin\u00a0\u00a0\u00a0\u00a0 \u7b49\u4ef7\u4e8e\u201d=any\u201d<br \/>\nexists\u00a0 \u8868\u793a\u5b50\u67e5\u8be2\u81f3\u5c11\u8981\u8fd4\u56de\u4e00\u6761\u8bb0\u5f55<\/p>\n<p>\u67e5\u8be2\u5927\u4e8e\u7b49\u4e8e20\u4e2a\u5b66\u751f\u7684\u73ed\u7ea7\uff1a<\/p>\n<p>Query query = session.createQuery(\u201cfrom Team t where(select count(*) from t.students)&gt;=20\u201d);<\/p>\n<p>\u67e5\u8be2\u6240\u6709\u5b66\u751f\u5e74\u9f84\u4e0d\u5c0f\u4e8e21\u5c81\u7684\u73ed\u7ea7\u5bf9\u8c61<\/p>\n<p>From Team t where 21&lt;all (select s.age from t.students s)<\/p>\n<p>\u6ce8\u610f\uff1aMySQL\u4ece4.1x\u7248\u672c\u624d\u652f\u6301\u5b50\u67e5\u8be2\uff0c\u4ee5\u524d\u7684\u7248\u672c\u4e2d\u53ef\u7528\u8fde\u63a5\u67e5\u8be2\u548c\u5206\u7ec4\u67e5\u8be2\u53d6\u4ee3\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4e94\u3001\u5bf9\u8c61\u5728Hibernate\u4e2d\u7684\u72b6\u6001 \u5bf9\u8c61\u5728Hibernate\u4e2d\u7684\u72b6\u6001\u56fe\uff1a \u5bf9\u8c613\u79cd\u72b6\u6001\uff1a\u00a0 Transient(\u77ac\u65f6\/\u4e34\u65f6)\u00a0\u00a0 Persistent(\u6301\u4e45)\u00a0 Detached(\u8131\u7ba1\/\u6e38\u79bb) \u77ac\u65f6\u72b6\u6001(Transient)\uff1a \u5728\u5185\u5b58\u4e2d\u521a\u521a\u521b\u5efa\u7684\u5bf9&hellip;<\/p>\n","protected":false},"author":13,"featured_media":7702,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[],"class_list":["post-1725","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-t"],"_links":{"self":[{"href":"https:\/\/www.justzz.com\/spec\/wp-json\/wp\/v2\/posts\/1725","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.justzz.com\/spec\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.justzz.com\/spec\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.justzz.com\/spec\/wp-json\/wp\/v2\/users\/13"}],"replies":[{"embeddable":true,"href":"https:\/\/www.justzz.com\/spec\/wp-json\/wp\/v2\/comments?post=1725"}],"version-history":[{"count":0,"href":"https:\/\/www.justzz.com\/spec\/wp-json\/wp\/v2\/posts\/1725\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.justzz.com\/spec\/wp-json\/wp\/v2\/media\/7702"}],"wp:attachment":[{"href":"https:\/\/www.justzz.com\/spec\/wp-json\/wp\/v2\/media?parent=1725"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.justzz.com\/spec\/wp-json\/wp\/v2\/categories?post=1725"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.justzz.com\/spec\/wp-json\/wp\/v2\/tags?post=1725"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}