{"id":201030,"date":"2025-05-06T13:27:04","date_gmt":"2025-05-06T05:27:04","guid":{"rendered":"https:\/\/server.hk\/cnblog\/201030\/"},"modified":"2025-05-06T13:27:04","modified_gmt":"2025-05-06T05:27:04","slug":"jpa-%e5%8a%a8%e6%80%81%e6%9d%a1%e4%bb%b6-sql-%e4%b8%ad%e5%a6%82%e4%bd%95%e4%bc%98%e9%9b%85%e5%a4%84%e7%90%86-null-%e5%80%bc%ef%bc%9f","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/201030\/","title":{"rendered":"JPA \u52a8\u6001\u6761\u4ef6 SQL \u4e2d\u5982\u4f55\u4f18\u96c5\u5904\u7406 NULL \u503c\uff1f"},"content":{"rendered":"

<\/b> <\/p>\n

JPA \u52a8\u6001\u6761\u4ef6 SQL \u4e2d\u5982\u4f55\u4f18\u96c5\u5904\u7406 NULL \u503c\uff1f<\/h1>\n

\u5077\u5077\u52aa\u529b\uff0c\u6084\u65e0\u58f0\u606f\u5730\u53d8\u5f3a\uff0c\u7136\u540e\u60ca\u8273\u6240\u6709\u4eba\uff01\u54c8\u54c8\uff0c\u5c0f\u4f19\u4f34\u4eec\u53c8\u6765\u5b66\u4e60\u5566~\u4eca\u5929\u6211\u5c06\u7ed9\u5927\u5bb6\u4ecb\u7ecd\uff0c\u8fd9\u7bc7\u6587\u7ae0\u4e3b\u8981\u4f1a\u8bb2\u5230\u7b49\u7b49\u77e5\u8bc6\u70b9\uff0c\u4e0d\u77e5\u9053\u5927\u5bb6\u5bf9\u5176\u90fd\u6709\u591a\u5c11\u4e86\u89e3\uff0c\u4e0b\u9762\u6211\u4eec\u5c31\u4e00\u8d77\u6765\u770b\u4e00\u5427\uff01\u5f53\u7136\uff0c\u975e\u5e38\u5e0c\u671b\u5927\u5bb6\u80fd\u591a\u591a\u8bc4\u8bba\uff0c\u7ed9\u51fa\u5408\u7406\u7684\u5efa\u8bae\uff0c\u6211\u4eec\u4e00\u8d77\u5b66\u4e60\uff0c\u4e00\u8d77\u8fdb\u6b65\uff01<\/p>\n

<\/p>\n

\u5728 JPA \u52a8\u6001\u6761\u4ef6 SQL \u4e2d\u4f7f\u7528 IFNULL<\/strong><\/p>\n

\u5728\u4f7f\u7528 JPA \u8fdb\u884c\u591a\u8868\u8054\u5408\u52a8\u6001 SQL \u67e5\u8be2\u65f6\uff0c\u5982\u679c\u9700\u8981\u5224\u65ad\u67d0\u4e2a\u5b57\u6bb5\u662f\u5426\u4e3a\u7a7a\uff0c\u53ef\u80fd\u4f1a\u4f7f\u7528 IFNULL(NULLIF(?1,”),’xxx\u5b57\u6bb5’) \u8fd9\u6837\u7684\u8868\u8fbe\u5f0f\u3002\u7136\u800c\uff0c\u8fd9\u79cd\u5199\u6cd5\u5b58\u5728\u4e00\u5b9a\u7684\u5f0a\u7aef\u3002<\/p>\n

\u9996\u5148\uff0c\u5b83\u589e\u52a0\u4e86 SQL \u67e5\u8be2\u7684\u590d\u6742\u6027\u3002\u5f53\u4f7f\u7528\u591a\u4e2a\u6761\u4ef6\u62fc\u63a5\u65f6\uff0c\u8fd9\u79cd\u8868\u8fbe\u5f0f\u4f1a\u4f7f SQL \u8bed\u53e5\u53d8\u5f97\u5197\u957f\u96be\u4ee5\u9605\u8bfb\uff0c\u8fd9\u5c06\u5f71\u54cd\u53ef\u7ef4\u62a4\u6027\u3002<\/p>\n

\u5176\u6b21\uff0c\u5b83\u5bf9 MySQL \u7684\u6027\u80fd\u6709\u635f\u8017\u3002IFNULL \u51fd\u6570\u672c\u8d28\u4e0a\u662f\u4e00\u4e2a CASE \u8868\u8fbe\u5f0f\uff0c\u5b83\u9700\u8981\u5728\u8fd0\u884c\u65f6\u8fdb\u884c\u989d\u5916\u7684\u8ba1\u7b97\uff0c\u964d\u4f4e\u67e5\u8be2\u7684\u6267\u884c\u6548\u7387\u3002<\/p>\n

\u6700\u540e\uff0c\u8fd9\u79cd\u5199\u6cd5\u4e0d\u7b26\u5408 SQL \u6807\u51c6\u3002\u867d\u7136\u5b83\u5728 MySQL \u4e2d\u53ef\u4ee5\u901a\u8fc7\uff0c\u4f46\u662f\u5728\u5176\u4ed6\u6570\u636e\u5e93\u7cfb\u7edf\u4e2d\u53ef\u80fd\u4f1a\u51fa\u73b0\u95ee\u9898\u3002\u4e3a\u4e86\u4fdd\u8bc1\u4ee3\u7801\u7684\u8de8\u5e73\u53f0\u517c\u5bb9\u6027\uff0c\u6700\u597d\u907f\u514d\u4f7f\u7528\u8fd9\u79cd non-standard \u7684\u5199\u6cd5\u3002<\/p>\n

\u6700\u4f73\u5b9e\u8df5\u662f\u5728\u4ee3\u7801\u5c42\u9762\u63a7\u5236\u6b64\u7c7b\u903b\u8f91\uff0c\u800c\u4e0d\u662f\u4f9d\u8d56\u4e8e MySQL \u7684\u51fd\u6570\u3002\u4e5f\u53ef\u4ee5\u901a\u8fc7\u4ed4\u7ec6\u8bbe\u8ba1\u8868\u7ed3\u6784\uff0c\u907f\u514d\u4f7f\u7528 NULL \u503c\uff0c\u4ee5\u63d0\u9ad8\u67e5\u8be2\u6027\u80fd\u3002<\/p>\n

\u4eca\u5929\u5e26\u5927\u5bb6\u4e86\u89e3\u4e86\u7684\u76f8\u5173\u77e5\u8bc6\uff0c\u5e0c\u671b\u5bf9\u4f60\u6709\u6240\u5e2e\u52a9\uff1b\u5173\u4e8e\u6570\u636e\u5e93\u7684\u6280\u672f\u77e5\u8bc6\u6211\u4eec\u4f1a\u4e00\u70b9\u70b9\u6df1\u5165\u4ecb\u7ecd\uff0c\u6b22\u8fce\u5927\u5bb6\u5173\u6ce8\u4e3b\u673a\u5b9d\u8d1d\u516c\u4f17\u53f7\uff0c\u4e00\u8d77\u5b66\u4e60\u7f16\u7a0b~<\/p>\n

\n
\n <\/dt>\n<\/dl>\n","protected":false},"excerpt":{"rendered":"

JPA \u52a8\u6001\u6761\u4ef6 SQL \u4e2d\u5982\u4f55...<\/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-201030","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/201030","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=201030"}],"version-history":[{"count":0,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/201030\/revisions"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=201030"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=201030"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=201030"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}