{"id":200835,"date":"2025-05-06T11:28:12","date_gmt":"2025-05-06T03:28:12","guid":{"rendered":"https:\/\/server.hk\/cnblog\/200835\/"},"modified":"2025-05-06T11:28:12","modified_gmt":"2025-05-06T03:28:12","slug":"jpa-%e5%8a%a8%e6%80%81%e6%9d%a1%e4%bb%b6-sql-%e4%bd%bf%e7%94%a8-ifnull-%e6%97%b6%ef%bc%8c%e4%b8%ba%e4%bb%80%e4%b9%88%e6%9f%a5%e8%af%a2%e7%bb%93%e6%9e%9c%e6%b2%a1%e6%9c%89%e8%bf%87%e6%bb%a4%e4%bb%bb","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/200835\/","title":{"rendered":"JPA \u52a8\u6001\u6761\u4ef6 SQL \u4f7f\u7528 IFNULL() \u65f6\uff0c\u4e3a\u4ec0\u4e48\u67e5\u8be2\u7ed3\u679c\u6ca1\u6709\u8fc7\u6ee4\u4efb\u4f55\u884c\uff1f"},"content":{"rendered":"<p><b><\/b> <\/p>\n<h1>JPA \u52a8\u6001\u6761\u4ef6 SQL \u4f7f\u7528 IFNULL() \u65f6\uff0c\u4e3a\u4ec0\u4e48\u67e5\u8be2\u7ed3\u679c\u6ca1\u6709\u8fc7\u6ee4\u4efb\u4f55\u884c\uff1f<\/h1>\n<p>\u4eca\u65e5\u4e0d\u80af\u57cb\u5934\uff0c\u660e\u65e5\u4f55\u4ee5\u62ac\u5934\uff01\u6bcf\u65e5\u4e00\u53e5\u52aa\u529b\u81ea\u5df1\u7684\u8bdd\u54c8\u54c8~\u54c8\u55bd\uff0c\u4eca\u5929\u6211\u5c06\u7ed9\u5927\u5bb6\u5e26\u6765\u4e00\u7bc7\uff0c\u4e3b\u8981\u5185\u5bb9\u662f\u8bb2\u89e3\u7b49\u7b49\uff0c\u611f\u5174\u8da3\u7684\u670b\u53cb\u53ef\u4ee5\u6536\u85cf\u6216\u8005\u6709\u66f4\u597d\u7684\u5efa\u8bae\u5728\u8bc4\u8bba\u63d0\u51fa\uff0c\u6211\u90fd\u4f1a\u8ba4\u771f\u770b\u7684\uff01\u5927\u5bb6\u4e00\u8d77\u8fdb\u6b65\uff0c\u4e00\u8d77\u5b66\u4e60\uff01<\/p>\n<p><img decoding=\"async\" src=\"https:\/\/www.17golang.com\/uploads\/20241116\/1731746209673859a1e5265.jpg\" class=\"aligncenter\"><\/p>\n<p>\u5728 jpa \u52a8\u6001\u6761\u4ef6 sql \u4e2d\u9047\u5230 ifnull() \u95ee\u9898<\/p>\n<p>\u5728\u4f7f\u7528 jpa \u6765\u521b\u5efa\u52a8\u6001 sql \u6761\u4ef6\u65f6\uff0c\u60a8\u53ef\u80fd\u66fe\u5c1d\u8bd5\u8fc7\u4ee5\u4e0b\u4ee3\u7801\uff1a<\/p>\n<pre>where ifnull(nullif(?1,''),'xxx\u5b57\u6bb5')<\/pre>\n<p>\u7136\u800c\uff0c\u60a8\u6ce8\u610f\u5230\u4e86\u4e00\u4e2a\u95ee\u9898\uff1a\u6267\u884c\u6b64\u4ee3\u7801\u540e\uff0c\u67e5\u8be2\u7ed3\u679c\u76f8\u5f53\u4e8e\uff1a<\/p>\n<pre>where xxx\u5b57\u6bb5 = xxx\u5b57\u6bb5<\/pre>\n<p>\u8fd9\u662f\u600e\u4e48\u56de\u4e8b\uff0c\u6709\u89e3\u51b3\u529e\u6cd5\u5417\uff1f<\/p>\n<p>\u56de\u7b54\uff1a<\/p>\n<p>ifnull() \u51fd\u6570\u7684\u4f5c\u7528\u662f\u68c0\u67e5\u7b2c\u4e00\u4e2a\u53c2\u6570\u662f\u5426\u4e3a null\uff0c\u5982\u679c\u662f\uff0c\u5219\u8fd4\u56de\u7b2c\u4e8c\u4e2a\u53c2\u6570\u3002\u5728\u60a8\u7684\u60c5\u51b5\u4e0b\uff0c\u7b2c\u4e00\u4e2a\u53c2\u6570\u662f\u53ef\u4e3a null \u7684\u53d8\u91cf ?1\uff0c\u7b2c\u4e8c\u4e2a\u53c2\u6570\u662f\u5b57\u7b26\u4e32 &#8216;xxx\u5b57\u6bb5&#8217;.<\/p>\n<p>mysql \u5728\u5904\u7406\u6b64\u4ee3\u7801\u65f6\uff0c\u5b83\u5c06\u6267\u884c\u4ee5\u4e0b\u64cd\u4f5c\uff1a<\/p>\n<ol>\n<li>\u68c0\u67e5 ?1 \u662f\u5426\u4e3a null\u3002<\/li>\n<li>\u5982\u679c ?1 \u4e0d\u4e3a null\uff0c\u5219\u8fd4\u56de\u5b83\u3002<\/li>\n<li>\u5982\u679c ?1 \u4e3a null\uff0c\u5219\u8fd4\u56de &#8216;xxx\u5b57\u6bb5&#8217;\u3002<\/li>\n<\/ol>\n<p>\u7136\u800c\uff0c\u6700\u540e\u4e00\u79cd\u60c5\u51b5\u6c38\u8fdc\u4e0d\u4f1a\u53d1\u751f\uff0c\u56e0\u4e3a nullif() \u51fd\u6570\u786e\u4fdd ?1 \u6c38\u8fdc\u4e0d\u4f1a\u4e3a null\u3002\u56e0\u6b64\uff0c\u67e5\u8be2\u59cb\u7ec8\u4f1a\u6267\u884c where xxx\u5b57\u6bb5 = xxx\u5b57\u6bb5\uff0c\u5e76\u4e14\u4e0d\u4f1a\u8fc7\u6ee4\u4efb\u4f55\u884c\u3002<\/p>\n<p>\u6700\u4f73\u5b9e\u8df5\u5efa\u8bae\u662f\u4f7f\u7528\u4ee3\u7801\u8fdb\u884c\u6761\u4ef6\u63a7\u5236\u3002\u907f\u514d\u4f9d\u8d56 mysql \u6765\u5904\u7406\u7a7a\u503c\uff0c\u56e0\u4e3a\u5b83\u53ef\u80fd\u4f1a\u635f\u5bb3\u6027\u80fd\u3002\u6b64\u5916\uff0c\u5728\u8bbe\u8ba1\u8868\u65f6\uff0c\u5c3d\u53ef\u80fd\u907f\u514d\u4f7f\u7528 null \u503c\u3002<\/p>\n<p>\u7ec8\u4e8e\u4ecb\u7ecd\u5b8c\u5566\uff01\u5c0f\u4f19\u4f34\u4eec\uff0c\u8fd9\u7bc7\u5173\u4e8e\u300aJPA \u52a8\u6001\u6761\u4ef6 SQL \u4f7f\u7528 IFNULL() \u65f6\uff0c\u4e3a\u4ec0\u4e48\u67e5\u8be2\u7ed3\u679c\u6ca1\u6709\u8fc7\u6ee4\u4efb\u4f55\u884c\uff1f\u300b\u7684\u4ecb\u7ecd\u5e94\u8be5\u8ba9\u4f60\u6536\u83b7\u591a\u591a\u4e86\u5427\uff01\u6b22\u8fce\u5927\u5bb6\u6536\u85cf\u6216\u5206\u4eab\u7ed9\u66f4\u591a\u9700\u8981\u5b66\u4e60\u7684\u670b\u53cb\u5427~\u4e3b\u673a\u5b9d\u8d1d\u516c\u4f17\u53f7\u4e5f\u4f1a\u53d1\u5e03\u6570\u636e\u5e93\u76f8\u5173\u77e5\u8bc6\uff0c\u5feb\u6765\u5173\u6ce8\u5427\uff01<\/p>\n<dl>\n<dt>\n <\/dt>\n<\/dl>\n","protected":false},"excerpt":{"rendered":"<p>JPA \u52a8\u6001\u6761\u4ef6 SQL \u4f7f\u7528 &#46;&#46;&#46;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[101],"tags":[],"class_list":["post-200835","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/200835","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"}],"author":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/comments?post=200835"}],"version-history":[{"count":0,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/200835\/revisions"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=200835"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=200835"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=200835"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}