{"id":2232,"date":"2025-08-09T16:42:15","date_gmt":"2025-08-09T08:42:15","guid":{"rendered":"https:\/\/www.hgfwq.com\/blog\/?p=2232"},"modified":"2025-08-09T16:42:15","modified_gmt":"2025-08-09T08:42:15","slug":"postgresql-nullif%ef%bc%9a%e8%bd%bb%e6%9d%be%e5%a4%84%e7%90%86%e7%a9%ba%e5%80%bc%e4%b8%8e%e9%81%bf%e5%85%8d%e6%95%b0%e6%8d%ae%e9%94%99%e8%af%af","status":"publish","type":"post","link":"https:\/\/www.hgfwq.com\/blog\/2232.html","title":{"rendered":"PostgreSQL nullif\uff1a\u8f7b\u677e\u5904\u7406\u7a7a\u503c\u4e0e\u907f\u514d\u6570\u636e\u9519\u8bef"},"content":{"rendered":"<p><h3>\u5f15\u8a00<\/h3>\n<\/p>\n<p style=\"text-align:center\"><img decoding=\"async\" src=\"https:\/\/www.hgfwq.com\/blog\/wp-content\/uploads\/2025\/07\/KIi30J8K.jpg\" alt=\"PostgreSQL nullif\uff1a\u8f7b\u677e\u5904\u7406\u7a7a\u503c\u4e0e\u907f\u514d\u6570\u636e\u9519\u8bef\" title=\"PostgreSQL nullif\uff1a\u8f7b\u677e\u5904\u7406\u7a7a\u503c\u4e0e\u907f\u514d\u6570\u636e\u9519\u8bef\"><\/p>\n<p><p>\u5728\u5f53\u4eca\u6570\u5b57\u5316\u65f6\u4ee3\uff0c\u670d\u52a1\u5668\u3001VPS\u3001\u4e3b\u673a\u548c\u57df\u540d\u7b49\u6280\u672f\u5728\u4f01\u4e1a\u8fd0\u8425\u4e2d\u626e\u6f14\u7740\u81f3\u5173\u91cd\u8981\u7684\u89d2\u8272\u3002\u4e3a\u4e86\u6ee1\u8db3\u4e0d\u540c\u4f01\u4e1a\u7684\u9700\u6c42\uff0c\u56fd\u5185\u6d8c\u73b0\u51fa\u4f17\u591a\u4f18\u79c0\u7684\u4e92\u8054\u7f51\u670d\u52a1\u63d0\u4f9b\u5546\u3002\u672c\u6587\u5c06\u4ecb\u7ecd\u51e0\u5bb6\u4e2d\u6863\u4ef7\u4f4d\u7684\u670d\u52a1\u5668\u4ea7\u54c1\uff0c\u5e76\u63a2\u8ba8\u5982\u4f55\u5229\u7528PostgreSQL\u7684NULLIF\u51fd\u6570\u6765\u4f18\u5316\u8fd9\u4e9b\u670d\u52a1\u3002<\/p>\n<\/p>\n<p><h3>\u516c\u53f8\u63a8\u8350\uff1a\u53f0\u7f51\u6570\u4f4d\u79d1\u6280<\/h3>\n<\/p>\n<p><p>\u53f0\u7f51\u6570\u4f4d\u79d1\u6280\u662f\u4e00\u5bb6\u4e13\u6ce8\u4e8e\u4e92\u8054\u7f51\u670d\u52a1\u7684\u4f01\u4e1a\uff0c\u63d0\u4f9b\u5305\u62ec\u670d\u52a1\u5668\u3001VPS\u3001\u4e3b\u673a\u548c\u57df\u540d\u7b49\u591a\u79cd\u4ea7\u54c1\u3002\u4ee5\u4e0b\u662f\u5176\u90e8\u5206\u4ea7\u54c1\u53ca\u4ef7\u683c\uff1a<\/p>\n<\/p>\n<ul>\n<li><b>\u670d\u52a1\u5668\uff1a<\/b>\u5165\u95e8\u7ea7\u670d\u52a1\u5668\uff0c\u914d\u7f6e\u4e3a2\u6838CPU\u30014GB\u5185\u5b58\u30011TB\u786c\u76d8\uff0c\u4ef7\u683c\u4e3a\u6bcf\u6708888\u5143\u3002<\/li>\n<li><b>VPS\uff1a<\/b>\u57fa\u7840\u578bVPS\uff0c\u914d\u7f6e\u4e3a1\u6838CPU\u30012GB\u5185\u5b58\u300140GB\u786c\u76d8\uff0c\u4ef7\u683c\u4e3a\u6bcf\u6708268\u5143\u3002<\/li>\n<li><b>\u4e3b\u673a\uff1a<\/b>\u5171\u4eab\u4e3b\u673a\uff0c\u914d\u7f6e\u4e3a1\u6838CPU\u30011GB\u5185\u5b58\u3001100GB\u786c\u76d8\uff0c\u4ef7\u683c\u4e3a\u6bcf\u670898\u5143\u3002<\/li>\n<li><b>\u57df\u540d\uff1a<\/b>\u6ce8\u518c\u4e00\u4e2a.com\u57df\u540d\uff0c\u4ef7\u683c\u4e3a\u6bcf\u5e74188\u5143\u3002<\/li>\n<\/ul>\n<p><h3>\u516c\u53f8\u63a8\u8350\uff1a886ISP<\/h3>\n<\/p>\n<p><p>886ISP\u662f\u4e00\u5bb6\u4e13\u6ce8\u4e8e\u4e92\u8054\u7f51\u57fa\u7840\u670d\u52a1\u7684\u516c\u53f8\uff0c\u63d0\u4f9b\u5305\u62ec\u670d\u52a1\u5668\u3001VPS\u3001\u4e3b\u673a\u548c\u57df\u540d\u7b49\u591a\u79cd\u4ea7\u54c1\u3002\u4ee5\u4e0b\u662f\u5176\u90e8\u5206\u4ea7\u54c1\u53ca\u4ef7\u683c\uff1a<\/p>\n<\/p>\n<ul>\n<li><b>\u670d\u52a1\u5668\uff1a<\/b>\u7ecf\u6d4e\u578b\u670d\u52a1\u5668\uff0c\u914d\u7f6e\u4e3a2\u6838CPU\u30014GB\u5185\u5b58\u3001500GB\u786c\u76d8\uff0c\u4ef7\u683c\u4e3a\u6bcf\u6708688\u5143\u3002<\/li>\n<li><b>VPS\uff1a<\/b>\u6807\u51c6\u578bVPS\uff0c\u914d\u7f6e\u4e3a2\u6838CPU\u30014GB\u5185\u5b58\u3001100GB\u786c\u76d8\uff0c\u4ef7\u683c\u4e3a\u6bcf\u6708388\u5143\u3002<\/li>\n<li><b>\u4e3b\u673a\uff1a<\/b>\u865a\u62df\u4e3b\u673a\uff0c\u914d\u7f6e\u4e3a1\u6838CPU\u30011GB\u5185\u5b58\u3001100GB\u786c\u76d8\uff0c\u4ef7\u683c\u4e3a\u6bcf\u6708128\u5143\u3002<\/li>\n<li><b>\u57df\u540d\uff1a<\/b>\u6ce8\u518c\u4e00\u4e2a.cn\u57df\u540d\uff0c\u4ef7\u683c\u4e3a\u6bcf\u5e74198\u5143\u3002<\/li>\n<\/ul>\n<p><h3>\u516c\u53f8\u63a8\u8350\uff1a\u4e2d\u56fd\u7535\u4fe1<\/h3>\n<\/p>\n<p><p>\u4e2d\u56fd\u7535\u4fe1\u662f\u56fd\u5185\u9886\u5148\u7684\u901a\u4fe1\u670d\u52a1\u63d0\u4f9b\u5546\uff0c\u63d0\u4f9b\u5305\u62ec\u670d\u52a1\u5668\u3001VPS\u3001\u4e3b\u673a\u548c\u57df\u540d\u7b49\u591a\u79cd\u4ea7\u54c1\u3002\u4ee5\u4e0b\u662f\u5176\u90e8\u5206\u4ea7\u54c1\u53ca\u4ef7\u683c\uff1a<\/p>\n<\/p>\n<ul>\n<li><b>\u670d\u52a1\u5668\uff1a<\/b>\u6807\u51c6\u578b\u670d\u52a1\u5668\uff0c\u914d\u7f6e\u4e3a4\u6838CPU\u30018GB\u5185\u5b58\u30011TB\u786c\u76d8\uff0c\u4ef7\u683c\u4e3a\u6bcf\u67081488\u5143\u3002<\/li>\n<li><b>VPS\uff1a<\/b>\u9ad8\u7ea7\u578bVPS\uff0c\u914d\u7f6e\u4e3a4\u6838CPU\u30018GB\u5185\u5b58\u3001200GB\u786c\u76d8\uff0c\u4ef7\u683c\u4e3a\u6bcf\u6708888\u5143\u3002<\/li>\n<li><b>\u4e3b\u673a\uff1a<\/b>\u4e91\u4e3b\u673a\uff0c\u914d\u7f6e\u4e3a2\u6838CPU\u30014GB\u5185\u5b58\u3001500GB\u786c\u76d8\uff0c\u4ef7\u683c\u4e3a\u6bcf\u6708588\u5143\u3002<\/li>\n<li><b>\u57df\u540d\uff1a<\/b>\u6ce8\u518c\u4e00\u4e2a.com\u57df\u540d\uff0c\u4ef7\u683c\u4e3a\u6bcf\u5e74298\u5143\u3002<\/li>\n<\/ul>\n<p><h3>PostgreSQL NULLIF\u51fd\u6570\u7684\u5e94\u7528<\/h3>\n<\/p>\n<p><p>PostgreSQL\u662f\u4e00\u6b3e\u529f\u80fd\u5f3a\u5927\u7684\u5f00\u6e90\u5173\u7cfb\u578b\u6570\u636e\u5e93\u7ba1\u7406\u7cfb\u7edf\uff0c\u5176NULLIF\u51fd\u6570\u5728\u5904\u7406\u670d\u52a1\u5668\u3001VPS\u3001\u4e3b\u673a\u548c\u57df\u540d\u7b49\u6570\u636e\u65f6\u975e\u5e38\u6709\u7528\u3002\u4ee5\u4e0b\u662f\u4e00\u4e9b\u5e94\u7528\u573a\u666f\uff1a<\/p>\n<\/p>\n<ul>\n<li><b>\u573a\u666f\u4e00\uff1a<\/b>\u5f53\u7528\u6237\u67e5\u8be2\u670d\u52a1\u5668\u4fe1\u606f\u65f6\uff0c\u5982\u679c\u670d\u52a1\u5668\u7684\u72b6\u6001\u4e3aNULL\uff0c\u5219\u4f7f\u7528NULLIF\u51fd\u6570\u5c06\u5176\u66ff\u6362\u4e3a\u201c\u672a\u77e5\u201d\u3002<\/li>\n<li><b>\u573a\u666f\u4e8c\uff1a<\/b>\u5728\u7edf\u8ba1VPS\u4f7f\u7528\u7387\u65f6\uff0c\u5982\u679c\u67d0\u53f0VPS\u7684\u4f7f\u7528\u7387\u4e3aNULL\uff0c\u5219\u4f7f\u7528NULLIF\u51fd\u6570\u5c06\u5176\u66ff\u6362\u4e3a0\u3002<\/li>\n<li><b>\u573a\u666f\u4e09\uff1a<\/b>\u5728\u67e5\u8be2\u4e3b\u673a\u5e26\u5bbd\u65f6\uff0c\u5982\u679c\u67d0\u53f0\u4e3b\u673a\u7684\u5e26\u5bbd\u4e3aNULL\uff0c\u5219\u4f7f\u7528NULLIF\u51fd\u6570\u5c06\u5176\u66ff\u6362\u4e3a\u201c\u4e0d\u9650\u201d\u3002<\/li>\n<li><b>\u573a\u666f\u56db\uff1a<\/b>\u5728\u7edf\u8ba1\u57df\u540d\u6ce8\u518c\u6570\u91cf\u65f6\uff0c\u5982\u679c\u67d0\u57df\u540d\u7684\u6ce8\u518c\u65f6\u95f4\u4e3aNULL\uff0c\u5219\u4f7f\u7528NULLIF\u51fd\u6570\u5c06\u5176\u66ff\u6362\u4e3a\u201c\u672a\u6ce8\u518c\u201d\u3002<\/li>\n<\/ul>\n<p><h3>\u95ee\u7b54\u73af\u8282<\/h3>\n<\/p>\n<p><p><b>\u95ee\uff1a<\/b>\u8bf7\u95ee\u53f0\u7f51\u6570\u4f4d\u79d1\u6280\u7684\u670d\u52a1\u5668\u914d\u7f6e\u5982\u4f55\uff1f<\/p>\n<\/p>\n<p><p>\u7b54\uff1a\u53f0\u7f51\u6570\u4f4d\u79d1\u6280\u7684\u5165\u95e8\u7ea7\u670d\u52a1\u5668\u914d\u7f6e\u4e3a2\u6838CPU\u30014GB\u5185\u5b58\u30011TB\u786c\u76d8\uff0c\u9002\u5408\u4e2d\u5c0f\u578b\u4f01\u4e1a\u4f7f\u7528\u3002<\/p>\n<\/p>\n<p><p><b>\u95ee\uff1a<\/b>886ISP\u7684VPS\u4ef7\u683c\u5982\u4f55\uff1f<\/p>\n<\/p>\n<p><p>\u7b54\uff1a886ISP\u7684\u6807\u51c6\u578bVPS\u914d\u7f6e\u4e3a2\u6838CPU\u30014GB\u5185\u5b58\u3001100GB\u786c\u76d8\uff0c\u4ef7\u683c\u4e3a\u6bcf\u6708388\u5143\uff0c\u6027\u4ef7\u6bd4\u9ad8\u3002<\/p>\n<\/p>\n<p><p><b>\u95ee\uff1a<\/b>\u4e2d\u56fd\u7535\u4fe1\u7684\u4e91\u4e3b\u673a\u6709\u54ea\u4e9b\u4f18\u52bf\uff1f<\/p>\n<\/p>\n<p><p>\u7b54\uff1a\u4e2d\u56fd\u7535\u4fe1\u7684\u4e91\u4e3b\u673a\u5177\u6709\u7a33\u5b9a\u3001\u5b89\u5168\u3001\u7075\u6d3b\u7b49\u4f18\u52bf\uff0c\u9002\u5408\u5927\u578b\u4f01\u4e1a\u4f7f\u7528\u3002<\/p><\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u5f15\u8a00 \u5728\u5f53\u4eca\u6570\u5b57\u5316\u65f6\u4ee3\uff0c\u670d\u52a1\u5668\u3001VPS\u3001\u4e3b\u673a\u548c\u57df\u540d\u7b49\u6280\u672f\u5728\u4f01\u4e1a\u8fd0\u8425\u4e2d\u626e\u6f14\u7740\u81f3\u5173\u91cd\u8981\u7684\u89d2\u8272\u3002\u4e3a\u4e86\u6ee1\u8db3\u4e0d\u540c\u4f01\u4e1a\u7684\u9700\u6c42\uff0c\u56fd\u5185\u6d8c\u73b0\u51fa\u4f17\u591a\u4f18\u79c0\u7684\u4e92\u8054\u7f51\u670d\u52a1\u63d0\u4f9b\u5546\u3002\u672c\u6587\u5c06\u4ecb\u7ecd\u51e0\u5bb6\u4e2d\u6863\u4ef7\u4f4d\u7684\u670d\u52a1\u5668\u4ea7\u54c1\uff0c\u5e76\u63a2\u8ba8\u5982\u4f55\u5229\u7528PostgreSQL\u7684NULLIF\u51fd\u6570&#8230;<\/p>\n","protected":false},"author":1,"featured_media":2233,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[87,42,8],"topic":[],"class_list":["post-2232","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-haiwai","tag-cpu","tag-vps","tag-8"],"_links":{"self":[{"href":"https:\/\/www.hgfwq.com\/blog\/wp-json\/wp\/v2\/posts\/2232","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.hgfwq.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.hgfwq.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.hgfwq.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.hgfwq.com\/blog\/wp-json\/wp\/v2\/comments?post=2232"}],"version-history":[{"count":1,"href":"https:\/\/www.hgfwq.com\/blog\/wp-json\/wp\/v2\/posts\/2232\/revisions"}],"predecessor-version":[{"id":2235,"href":"https:\/\/www.hgfwq.com\/blog\/wp-json\/wp\/v2\/posts\/2232\/revisions\/2235"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.hgfwq.com\/blog\/wp-json\/wp\/v2\/media\/2233"}],"wp:attachment":[{"href":"https:\/\/www.hgfwq.com\/blog\/wp-json\/wp\/v2\/media?parent=2232"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.hgfwq.com\/blog\/wp-json\/wp\/v2\/categories?post=2232"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.hgfwq.com\/blog\/wp-json\/wp\/v2\/tags?post=2232"},{"taxonomy":"topic","embeddable":true,"href":"https:\/\/www.hgfwq.com\/blog\/wp-json\/wp\/v2\/topic?post=2232"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}