{"id":6943,"date":"2024-11-14T12:12:25","date_gmt":"2024-11-14T04:12:25","guid":{"rendered":"https:\/\/fwq.ai\/blog\/6943\/"},"modified":"2024-11-14T12:12:25","modified_gmt":"2024-11-14T04:12:25","slug":"%e5%a6%82%e4%bd%95%e4%bd%bf%e7%94%a8-mysql-%e6%9f%a5%e8%af%a2%e7%bb%84%e5%90%88%e4%b8%8d%e5%90%8c%e5%ad%97%e6%ae%b5%e7%94%9f%e6%88%90%e6%96%b0%e5%ad%97%e6%ae%b5%ef%bc%9f","status":"publish","type":"post","link":"https:\/\/fwq.ai\/blog\/6943\/","title":{"rendered":"\u5982\u4f55\u4f7f\u7528 MySQL \u67e5\u8be2\u7ec4\u5408\u4e0d\u540c\u5b57\u6bb5\u751f\u6210\u65b0\u5b57\u6bb5\uff1f"},"content":{"rendered":"<p><img decoding=\"async\" src=\"https:\/\/img.php.cn\/upload\/article\/001\/246\/273\/173016509625456.jpg\" class=\"aligncenter\" title=\"\u5982\u4f55\u4f7f\u7528 MySQL \u67e5\u8be2\u7ec4\u5408\u4e0d\u540c\u5b57\u6bb5\u751f\u6210\u65b0\u5b57\u6bb5\uff1f\u63d2\u56fe\" alt=\"\u5982\u4f55\u4f7f\u7528 MySQL \u67e5\u8be2\u7ec4\u5408\u4e0d\u540c\u5b57\u6bb5\u751f\u6210\u65b0\u5b57\u6bb5\uff1f\u63d2\u56fe\" \/><\/p>\n<p><strong>\u5982\u4f55\u4f7f\u7528  \u67e5\u8be2\u89c4\u5219\u7ec4\u5408\u4e0d\u540c\u5b57\u6bb5\u751f\u6210\u65b0\u5b57\u6bb5\uff1f<\/strong><\/p>\n<p>\u5047\u8bbe\u6211\u4eec\u6709\u4e00\u4e2a\u8868\u683c\uff0c\u5176\u4e2d\u4fdd\u5b58\u4e86\u4e24\u5217\u4ef7\u683c\u4fe1\u606f\uff1a\u201c\u4ef7\u683c1\u201d\u548c\u201c\u4ef7\u683c2\u201d\u3002\u6211\u4eec\u9700\u8981\u521b\u5efa\u4e00\u4e2a\u65b0\u5b57\u6bb5\u201c\u4ef7\u683c\u201d\uff0c\u5176\u89c4\u5219\u5982\u4e0b\uff1a<\/p>\n<ul>\n<li>\u5982\u679c\u201c\u4ef7\u683c2\u201d\u4e0d\u4e3a\u7a7a\uff0c\u5219\u201c\u4ef7\u683c\u201d\u4e3a\u201c\u4ef7\u683c2\u201d\u3002<\/li>\n<li>\u5982\u679c\u201c\u4ef7\u683c2\u201d\u4e3a\u7a7a\uff0c\u5219\u201c\u4ef7\u683c\u201d\u4e3a\u201c\u4ef7\u683c1\u201d\u3002<\/li>\n<\/ul>\n<p>\u8981\u83b7\u5f97\u7b26\u5408\u8fd9\u4e9b\u89c4\u5219\u7684\u4ef7\u683c\uff0c\u6211\u4eec\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b mysql \u67e5\u8be2\uff1a<\/p>\n<pre>select id, if (\u4ef7\u683c2 is not null, \u4ef7\u683c2\uff0c\u4ef7\u683c1) as price<\/pre>\n<p> \u767b\u5f55\u540e\u590d\u5236 <\/p>\n<p>\u5728\u8fd9\u4e2a\u67e5\u8be2\u4e2d\uff0c\u6211\u4eec\u4f7f\u7528 if() \u51fd\u6570\u6765\u68c0\u67e5 \u4ef7\u683c2 \u662f\u5426\u4e3a\u7a7a\u3002\u5982\u679c\u4e3a\u7a7a\uff0cif() \u51fd\u6570\u5c06\u8fd4\u56de \u4ef7\u683c1\uff1b\u5426\u5219\uff0c\u5c06\u8fd4\u56de \u4ef7\u683c2\u3002<\/p>\n<p>\u67e5\u8be2\u7ed3\u679c\u5c06\u4e3a\u6211\u4eec\u63d0\u4f9b\u4e00\u4e2a\u5e26\u6709\u65b0\u5b57\u6bb5\u201c\u4ef7\u683c\u201d\u7684\u65b0\u7ed3\u679c\u96c6\uff0c\u8be5\u5b57\u6bb5\u5305\u542b\u6839\u636e\u4ee5\u4e0a\u89c4\u5219\u8ba1\u7b97\u7684\u4ef7\u683c\u3002<\/p>\n<p>\u4ee5\u4e0a\u5c31\u662f\u5982\u4f55\u4f7f\u7528 MySQL \u67e5\u8be2\u7ec4\u5408\u4e0d\u540c\u5b57\u6bb5\u751f\u6210\u65b0\u5b57\u6bb5\uff1f\u7684\u8be6\u7ec6\u5185\u5bb9\uff0c\u66f4\u591a\u8bf7\u5173\u6ce8\u7c73\u4e91\u7f51\u5176\u5b83\u76f8\u5173\u6587\u7ae0\uff01<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u5982\u4f55\u4f7f\u7528 \u67e5\u8be2\u89c4\u5219\u7ec4\u5408\u4e0d\u540c\u5b57\u6bb5\u751f\u6210\u65b0\u5b57\u6bb5\uff1f \u5047\u8bbe\u6211\u4eec\u6709\u4e00\u4e2a\u8868\u683c\uff0c\u5176\u4e2d\u4fdd\u5b58\u4e86\u4e24\u5217\u4ef7\u683c\u4fe1\u606f\uff1a\u201c\u4ef7\u683c1\u201d\u548c\u201c\u4ef7\u683c2\u201d\u3002\u6211\u4eec\u9700\u8981\u521b\u5efa\u4e00\u4e2a\u65b0\u5b57\u6bb5\u201c\u4ef7\u683c\u201d\uff0c\u5176\u89c4\u5219\u5982\u4e0b\uff1a \u5982\u679c\u201c\u4ef7\u683c2\u201d\u4e0d\u4e3a\u7a7a\uff0c\u5219\u201c\u4ef7\u683c\u201d\u4e3a\u201c\u4ef7\u683c2\u201d\u3002 \u5982\u679c\u201c\u4ef7\u683c2\u201d\u4e3a\u7a7a\uff0c\u5219\u201c\u4ef7\u683c\u201d\u4e3a\u201c\u4ef7\u683c1\u201d\u3002 \u8981\u83b7\u5f97\u7b26\u5408\u8fd9\u4e9b\u89c4\u5219\u7684\u4ef7\u683c\uff0c\u6211\u4eec\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b mysql \u67e5\u8be2\uff1a select id, if (\u4ef7\u683c2 is not null, \u4ef7\u683c2\uff0c\u4ef7\u683c1) as price \u767b\u5f55\u540e\u590d\u5236 \u5728\u8fd9\u4e2a\u67e5\u8be2\u4e2d\uff0c\u6211\u4eec\u4f7f\u7528 if() \u51fd\u6570\u6765\u68c0\u67e5 \u4ef7\u683c2 \u662f\u5426\u4e3a\u7a7a\u3002\u5982\u679c\u4e3a\u7a7a\uff0cif() \u51fd\u6570\u5c06\u8fd4\u56de \u4ef7\u683c1\uff1b\u5426\u5219\uff0c\u5c06\u8fd4\u56de \u4ef7\u683c2\u3002 \u67e5\u8be2\u7ed3\u679c\u5c06\u4e3a\u6211\u4eec\u63d0\u4f9b\u4e00\u4e2a\u5e26\u6709\u65b0\u5b57\u6bb5\u201c\u4ef7\u683c\u201d\u7684\u65b0\u7ed3\u679c\u96c6\uff0c\u8be5\u5b57\u6bb5\u5305\u542b\u6839\u636e\u4ee5\u4e0a\u89c4\u5219\u8ba1\u7b97\u7684\u4ef7\u683c\u3002 \u4ee5\u4e0a\u5c31\u662f\u5982\u4f55\u4f7f\u7528 MySQL \u67e5\u8be2\u7ec4\u5408\u4e0d\u540c\u5b57\u6bb5\u751f\u6210\u65b0\u5b57\u6bb5\uff1f\u7684\u8be6\u7ec6\u5185\u5bb9\uff0c\u66f4\u591a\u8bf7\u5173\u6ce8\u7c73\u4e91\u7f51\u5176\u5b83\u76f8\u5173\u6587\u7ae0\uff01<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[16],"tags":[],"class_list":["post-6943","post","type-post","status-publish","format-standard","hentry","category-16"],"_links":{"self":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts\/6943","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/comments?post=6943"}],"version-history":[{"count":0,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts\/6943\/revisions"}],"wp:attachment":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/media?parent=6943"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/categories?post=6943"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/tags?post=6943"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}