{"id":5676,"date":"2024-11-14T13:57:11","date_gmt":"2024-11-14T05:57:11","guid":{"rendered":"https:\/\/fwq.ai\/blog\/5676\/"},"modified":"2024-11-14T13:57:11","modified_gmt":"2024-11-14T05:57:11","slug":"sql%e6%80%8e%e4%b9%88%e8%bf%9e%e6%8e%a5%e4%b8%a4%e4%b8%aa%e5%ad%97%e7%ac%a6%e4%b8%b2","status":"publish","type":"post","link":"https:\/\/fwq.ai\/blog\/5676\/","title":{"rendered":"sql\u600e\u4e48\u8fde\u63a5\u4e24\u4e2a\u5b57\u7b26\u4e32"},"content":{"rendered":"<blockquote><p>\n  sql \u8fde\u63a5\u4e24\u4e2a\u5b57\u7b26\u4e32\u7684\u65b9\u6cd5\u6709\u4e09\u79cd\uff1a\u4f7f\u7528\u52a0\u53f7\u8fd0\u7b97\u7b26 (+)\u3001\u4f7f\u7528 concat() \u51fd\u6570\u6216\u4f7f\u7528 || \u64cd\u4f5c\u7b26\uff08\u4ec5\u9650 mysql\uff09\u3002\n<\/p><\/blockquote>\n<p><img decoding=\"async\" src=\"https:\/\/img.php.cn\/upload\/article\/202405\/30\/2024053020245566797.jpg\" class=\"aligncenter\" title=\"sql\u600e\u4e48\u8fde\u63a5\u4e24\u4e2a\u5b57\u7b26\u4e32\u63d2\u56fe\" alt=\"sql\u600e\u4e48\u8fde\u63a5\u4e24\u4e2a\u5b57\u7b26\u4e32\u63d2\u56fe\" \/><\/p>\n<p><strong>\u5982\u4f55\u4f7f\u7528 SQL \u8fde\u63a5\u4e24\u4e2a\u5b57\u7b26\u4e32\uff1f<\/strong><\/p>\n<p>SQL \u4e2d\u8fde\u63a5\u4e24\u4e2a\u5b57\u7b26\u4e32\u7684\u65b9\u6cd5\u5982\u4e0b\uff1a<\/p>\n<p><strong>1. \u4f7f\u7528\u52a0\u53f7\u8fd0\u7b97\u7b26 (+)<\/strong><\/p>\n<p>\u6700\u7b80\u5355\u7684\u65b9\u6cd5\u662f\u4f7f\u7528\u52a0\u53f7\u8fd0\u7b97\u7b26 (+)\uff0c\u5c06\u4e24\u4e2a\u5b57\u7b26\u4e32\u76f8\u52a0\u3002\u4f8b\u5982\uff1a<\/p>\n<pre>SELECT 'Hello' + ' ' + 'World';<\/pre>\n<p>  \u767b\u5f55\u540e\u590d\u5236   <\/p>\n<p>\u7ed3\u679c\uff1a<\/p>\n<pre>Hello World<\/pre>\n<p>  \u767b\u5f55\u540e\u590d\u5236    \u767b\u5f55\u540e\u590d\u5236    \u767b\u5f55\u540e\u590d\u5236   <\/p>\n<p><strong>2. \u4f7f\u7528 CONCAT() \u51fd\u6570<\/strong><\/p>\n<p>CONCAT() \u51fd\u6570\u4e5f\u53ef\u7528\u4e8e\u8fde\u63a5\u5b57\u7b26\u4e32\u3002\u5176\u8bed\u6cd5\u5982\u4e0b\uff1a<\/p>\n<pre>CONCAT(string1, string2, ...)<\/pre>\n<p>  \u767b\u5f55\u540e\u590d\u5236   <\/p>\n<p>\u4f8b\u5982\uff1a<\/p>\n<pre>SELECT CONCAT('Hello', ' ', 'World');<\/pre>\n<p>  \u767b\u5f55\u540e\u590d\u5236   <\/p>\n<p>\u7ed3\u679c\uff1a<\/p>\n<pre>Hello World<\/pre>\n<p>  \u767b\u5f55\u540e\u590d\u5236    \u767b\u5f55\u540e\u590d\u5236    \u767b\u5f55\u540e\u590d\u5236   <\/p>\n<p><strong>3. \u4f7f\u7528 || \u64cd\u4f5c\u7b26\uff08\u4ec5\u9650MySQL\uff09<\/strong><\/p>\n<p>\u5728 MySQL \u4e2d\uff0c\u8fd8\u53ef\u4ee5\u4f7f\u7528 || \u64cd\u4f5c\u7b26\u6765\u8fde\u63a5\u5b57\u7b26\u4e32\u3002\u5176\u8bed\u6cd5\u5982\u4e0b\uff1a<\/p>\n<pre>string1 || string2<\/pre>\n<p>  \u767b\u5f55\u540e\u590d\u5236   <\/p>\n<p>\u4f8b\u5982\uff1a<\/p>\n<pre>SELECT 'Hello' || ' ' || 'World';<\/pre>\n<p>  \u767b\u5f55\u540e\u590d\u5236   <\/p>\n<p>\u7ed3\u679c\uff1a<\/p>\n<pre>Hello World<\/pre>\n<p>  \u767b\u5f55\u540e\u590d\u5236    \u767b\u5f55\u540e\u590d\u5236    \u767b\u5f55\u540e\u590d\u5236   <\/p>\n<p><strong>\u6ce8\u610f\u4e8b\u9879\uff1a<\/strong><\/p>\n<ul>\n<li>\u5728\u67d0\u4e9b\u60c5\u51b5\u4e0b\uff0c\u60a8\u53ef\u80fd\u9700\u8981\u4e3a\u5b57\u7b26\u4e32\u6dfb\u52a0\u5355\u5f15\u53f7\u6216\u53cc\u5f15\u53f7\uff0c\u4ee5\u9632\u6b62 SQL \u5c06\u5176\u89e3\u91ca\u4e3a\u5217\u540d\u6216\u4fdd\u7559\u5b57\u3002<\/li>\n<li>\u5982\u679c\u60a8\u8981\u8fde\u63a5 NULL \u503c\uff0c\u5219\u7ed3\u679c\u5c06\u4e3a NULL\u3002<\/li>\n<\/ul>\n<p>\u4ee5\u4e0a\u5c31\u662fsql\u600e\u4e48\u8fde\u63a5\u4e24\u4e2a\u5b57\u7b26\u4e32\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>sql \u8fde\u63a5\u4e24\u4e2a\u5b57\u7b26\u4e32\u7684\u65b9\u6cd5\u6709\u4e09\u79cd\uff1a\u4f7f\u7528\u52a0\u53f7\u8fd0\u7b97\u7b26 (+)\u3001\u4f7f\u7528 concat() \u51fd\u6570\u6216\u4f7f\u7528 || \u64cd\u4f5c\u7b26\uff08\u4ec5\u9650 mysql\uff09\u3002 \u5982\u4f55\u4f7f\u7528 SQL \u8fde\u63a5\u4e24\u4e2a\u5b57\u7b26\u4e32\uff1f SQL \u4e2d\u8fde\u63a5\u4e24\u4e2a\u5b57\u7b26\u4e32\u7684\u65b9\u6cd5\u5982\u4e0b\uff1a 1. \u4f7f\u7528\u52a0\u53f7\u8fd0\u7b97\u7b26 (+) \u6700\u7b80\u5355\u7684\u65b9\u6cd5\u662f\u4f7f\u7528\u52a0\u53f7\u8fd0\u7b97\u7b26 (+)\uff0c\u5c06\u4e24\u4e2a\u5b57\u7b26\u4e32\u76f8\u52a0\u3002\u4f8b\u5982\uff1a SELECT &#8216;Hello&#8217; + &#8216; &#8216; + &#8216;World&#8217;; \u767b\u5f55\u540e\u590d\u5236 \u7ed3\u679c\uff1a Hello World \u767b\u5f55\u540e\u590d\u5236 \u767b\u5f55\u540e\u590d\u5236 \u767b\u5f55\u540e\u590d\u5236 2. \u4f7f\u7528 CONCAT() \u51fd\u6570 CONCAT() \u51fd\u6570\u4e5f\u53ef\u7528\u4e8e\u8fde\u63a5\u5b57\u7b26\u4e32\u3002\u5176\u8bed\u6cd5\u5982\u4e0b\uff1a CONCAT(string1, string2, &#8230;) \u767b\u5f55\u540e\u590d\u5236 \u4f8b\u5982\uff1a SELECT CONCAT(&#8216;Hello&#8217;, &#8216; &#8216;, &#8216;World&#8217;); \u767b\u5f55\u540e\u590d\u5236 \u7ed3\u679c\uff1a Hello World \u767b\u5f55\u540e\u590d\u5236 \u767b\u5f55\u540e\u590d\u5236 \u767b\u5f55\u540e\u590d\u5236 [&hellip;]<\/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-5676","post","type-post","status-publish","format-standard","hentry","category-16"],"_links":{"self":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts\/5676","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=5676"}],"version-history":[{"count":0,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts\/5676\/revisions"}],"wp:attachment":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/media?parent=5676"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/categories?post=5676"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/tags?post=5676"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}