{"id":76040,"date":"2024-10-16T03:21:18","date_gmt":"2024-10-15T19:21:18","guid":{"rendered":"https:\/\/server.hk\/cnblog\/76040\/"},"modified":"2024-10-16T03:21:18","modified_gmt":"2024-10-15T19:21:18","slug":"mysql-%e6%88%aa%e5%8f%96%e5%ad%97%e7%ac%a6%e4%b8%b2%e5%87%bd%e6%95%b8%e6%96%b9%e6%b3%95","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/76040\/","title":{"rendered":"MySQL \u622a\u53d6\u5b57\u7b26\u4e32\u51fd\u6578\u65b9\u6cd5"},"content":{"rendered":"<h1 id=\"mysql-%e6%88%aa%e5%8f%96%e5%ad%97%e7%ac%a6%e4%b8%b2%e5%87%bd%e6%95%b8%e6%96%b9%e6%b3%95-URvDGfldKD\">MySQL \u622a\u53d6\u5b57\u7b26\u4e32\u51fd\u6578\u65b9\u6cd5<\/h1>\n<p>\u5728\u6578\u64da\u5eab\u7ba1\u7406\u4e2d\uff0c\u5b57\u7b26\u4e32\u8655\u7406\u662f\u4e00\u500b\u5e38\u898b\u7684\u9700\u6c42\u3002MySQL \u63d0\u4f9b\u4e86\u591a\u7a2e\u51fd\u6578\u4f86\u622a\u53d6\u5b57\u7b26\u4e32\uff0c\u9019\u4e9b\u51fd\u6578\u53ef\u4ee5\u5e6b\u52a9\u958b\u767c\u8005\u5728\u67e5\u8a62\u548c\u6578\u64da\u8655\u7406\u904e\u7a0b\u4e2d\u9748\u6d3b\u5730\u64cd\u4f5c\u5b57\u7b26\u4e32\u3002\u672c\u6587\u5c07\u4ecb\u7d39 MySQL \u4e2d\u5e7e\u500b\u5e38\u7528\u7684\u622a\u53d6\u5b57\u7b26\u4e32\u51fd\u6578\u53ca\u5176\u7528\u6cd5\u3002<\/p>\n<h2 id=\"1-substring-%e5%87%bd%e6%95%b8-URvDGfldKD\">1. SUBSTRING \u51fd\u6578<\/h2>\n<p>SUBSTRING \u51fd\u6578\u662f MySQL \u4e2d\u6700\u5e38\u7528\u7684\u5b57\u7b26\u4e32\u622a\u53d6\u51fd\u6578\u4e4b\u4e00\u3002\u5b83\u7684\u57fa\u672c\u8a9e\u6cd5\u5982\u4e0b\uff1a<\/p>\n<pre><code>SUBSTRING(str, start, length)<\/code><\/pre>\n<p>\u5176\u4e2d\uff0c<code>str<\/code> \u662f\u8981\u622a\u53d6\u7684\u5b57\u7b26\u4e32\uff0c<code>start<\/code> \u662f\u958b\u59cb\u4f4d\u7f6e\uff08\u5f9e 1 \u958b\u59cb\uff09\uff0c<code>length<\/code> \u662f\u8981\u622a\u53d6\u7684\u5b57\u7b26\u6578\u3002<\/p>\n<h3 id=\"%e7%af%84%e4%be%8b-URvDGfldKD\">\u7bc4\u4f8b<\/h3>\n<p>\u5047\u8a2d\u6709\u4e00\u500b\u5b57\u7b26\u4e32 &#8220;Hello, World!&#8221;\uff0c\u6211\u5011\u60f3\u8981\u622a\u53d6 &#8220;Hello&#8221;\uff1a<\/p>\n<pre><code>SELECT SUBSTRING('Hello, World!', 1, 5); -- \u7d50\u679c\u70ba 'Hello'<\/code><\/pre>\n<h2 id=\"2-left-%e5%92%8c-right-%e5%87%bd%e6%95%b8-URvDGfldKD\">2. LEFT \u548c RIGHT \u51fd\u6578<\/h2>\n<p>LEFT \u548c RIGHT \u51fd\u6578\u5206\u5225\u7528\u65bc\u5f9e\u5b57\u7b26\u4e32\u7684\u5de6\u5074\u548c\u53f3\u5074\u622a\u53d6\u6307\u5b9a\u6578\u91cf\u7684\u5b57\u7b26\u3002\u5b83\u5011\u7684\u8a9e\u6cd5\u5982\u4e0b\uff1a<\/p>\n<pre><code>LEFT(str, length)<\/code><\/pre>\n<pre><code>RIGHT(str, length)<\/code><\/pre>\n<h3 id=\"%e7%af%84%e4%be%8b-URvDGfldKD\">\u7bc4\u4f8b<\/h3>\n<p>\u5982\u679c\u6211\u5011\u60f3\u5f9e &#8220;Hello, World!&#8221; \u4e2d\u7372\u53d6\u524d 5 \u500b\u5b57\u7b26\u548c\u6700\u5f8c 6 \u500b\u5b57\u7b26\uff0c\u53ef\u4ee5\u9019\u6a23\u505a\uff1a<\/p>\n<pre><code>SELECT LEFT('Hello, World!', 5);  -- \u7d50\u679c\u70ba 'Hello'<\/code><\/pre>\n<pre><code>SELECT RIGHT('Hello, World!', 6); -- \u7d50\u679c\u70ba 'World!'<\/code><\/pre>\n<h2 id=\"3-substring_index-%e5%87%bd%e6%95%b8-URvDGfldKD\">3. SUBSTRING_INDEX \u51fd\u6578<\/h2>\n<p>SUBSTRING_INDEX \u51fd\u6578\u7528\u65bc\u6839\u64da\u6307\u5b9a\u7684\u5206\u9694\u7b26\u622a\u53d6\u5b57\u7b26\u4e32\u3002\u5176\u8a9e\u6cd5\u5982\u4e0b\uff1a<\/p>\n<pre><code>SUBSTRING_INDEX(str, delim, count)<\/code><\/pre>\n<p>\u9019\u88e1\uff0c<code>delim<\/code> \u662f\u5206\u9694\u7b26\uff0c<code>count<\/code> \u662f\u8981\u8fd4\u56de\u7684\u5b50\u5b57\u7b26\u4e32\u7684\u6578\u91cf\u3002\u5982\u679c <code>count<\/code> \u662f\u6b63\u6578\uff0c\u5247\u5f9e\u5de6\u5074\u958b\u59cb\u622a\u53d6\uff1b\u5982\u679c\u662f\u8ca0\u6578\uff0c\u5247\u5f9e\u53f3\u5074\u958b\u59cb\u622a\u53d6\u3002<\/p>\n<h3 id=\"%e7%af%84%e4%be%8b-URvDGfldKD\">\u7bc4\u4f8b<\/h3>\n<p>\u5047\u8a2d\u6709\u4e00\u500b\u5b57\u7b26\u4e32 &#8220;apple,banana,cherry&#8221;\uff0c\u6211\u5011\u60f3\u8981\u7372\u53d6\u7b2c\u4e00\u500b\u6c34\u679c\uff1a<\/p>\n<pre><code>SELECT SUBSTRING_INDEX('apple,banana,cherry', ',', 1); -- \u7d50\u679c\u70ba 'apple'<\/code><\/pre>\n<p>\u5982\u679c\u6211\u5011\u60f3\u8981\u7372\u53d6\u6700\u5f8c\u4e00\u500b\u6c34\u679c\uff0c\u53ef\u4ee5\u9019\u6a23\u505a\uff1a<\/p>\n<pre><code>SELECT SUBSTRING_INDEX('apple,banana,cherry', ',', -1); -- \u7d50\u679c\u70ba 'cherry'<\/code><\/pre>\n<h2 id=\"4-concat-%e5%92%8c-concat_ws-%e5%87%bd%e6%95%b8-URvDGfldKD\">4. CONCAT \u548c CONCAT_WS \u51fd\u6578<\/h2>\n<p>\u96d6\u7136\u9019\u5169\u500b\u51fd\u6578\u4e3b\u8981\u7528\u65bc\u5b57\u7b26\u4e32\u7684\u9023\u63a5\uff0c\u4f46\u5b83\u5011\u4e5f\u53ef\u4ee5\u7528\u65bc\u622a\u53d6\u548c\u7d44\u5408\u5b57\u7b26\u4e32\u3002CONCAT \u51fd\u6578\u7684\u8a9e\u6cd5\u5982\u4e0b\uff1a<\/p>\n<pre><code>CONCAT(str1, str2, ...)<\/code><\/pre>\n<p>\u800c CONCAT_WS \u51fd\u6578\u5247\u5141\u8a31\u7528\u6236\u6307\u5b9a\u5206\u9694\u7b26\uff1a<\/p>\n<pre><code>CONCAT_WS(delim, str1, str2, ...)<\/code><\/pre>\n<h3 id=\"%e7%af%84%e4%be%8b-URvDGfldKD\">\u7bc4\u4f8b<\/h3>\n<p>\u5982\u679c\u6211\u5011\u60f3\u8981\u5c07 &#8220;Hello&#8221; \u548c &#8220;World&#8221; \u9023\u63a5\u8d77\u4f86\uff0c\u53ef\u4ee5\u9019\u6a23\u505a\uff1a<\/p>\n<pre><code>SELECT CONCAT('Hello', ' ', 'World'); -- \u7d50\u679c\u70ba 'Hello World'<\/code><\/pre>\n<p>\u4f7f\u7528 CONCAT_WS \u4f86\u9023\u63a5\u5b57\u7b26\u4e32\u4e26\u6dfb\u52a0\u5206\u9694\u7b26\uff1a<\/p>\n<pre><code>SELECT CONCAT_WS(', ', 'apple', 'banana', 'cherry'); -- \u7d50\u679c\u70ba 'apple, banana, cherry'<\/code><\/pre>\n<h2 id=\"%e7%b8%bd%e7%b5%90-URvDGfldKD\">\u7e3d\u7d50<\/h2>\n<p>MySQL \u63d0\u4f9b\u4e86\u591a\u7a2e\u622a\u53d6\u5b57\u7b26\u4e32\u7684\u51fd\u6578\uff0c\u9019\u4e9b\u51fd\u6578\u5728\u6578\u64da\u8655\u7406\u548c\u67e5\u8a62\u4e2d\u975e\u5e38\u6709\u7528\u3002\u901a\u904e\u4f7f\u7528 <code>SUBSTRING<\/code>\u3001<code>LEFT<\/code>\u3001<code>RIGHT<\/code>\u3001<code>SUBSTRING_INDEX<\/code> \u548c <code>CONCAT<\/code> \u7b49\u51fd\u6578\uff0c\u958b\u767c\u8005\u53ef\u4ee5\u9748\u6d3b\u5730\u64cd\u4f5c\u5b57\u7b26\u4e32\uff0c\u6eff\u8db3\u4e0d\u540c\u7684\u9700\u6c42\u3002<\/p>\n<p>\u5982\u679c\u60a8\u6b63\u5728\u5c0b\u627e\u9ad8\u6548\u7684 <a href=\"https:\/\/server.hk\">VPS<\/a> \u89e3\u6c7a\u65b9\u6848\uff0cServer.HK \u63d0\u4f9b\u591a\u7a2e\u9078\u64c7\uff0c\u9069\u5408\u5404\u7a2e\u9700\u6c42\u3002\u7121\u8ad6\u662f <a href=\"https:\/\/server.hk\">\u9999\u6e2f\u4f3a\u670d\u5668<\/a> \u9084\u662f <a href=\"https:\/\/server.hk\">\u96f2\u4f3a\u670d\u5668<\/a>\uff0c\u6211\u5011\u90fd\u80fd\u70ba\u60a8\u63d0\u4f9b\u7a69\u5b9a\u7684\u670d\u52d9\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u63a2\u7d22 MySQL \u4e2d\u7684\u5b57\u7b26\u4e32\u622a\u53d6\u51fd\u6570\uff0c\u4e86\u89e3\u5982\u4f55\u6709\u6548\u5904\u7406\u548c\u63d0\u53d6\u5b57\u7b26\u4e32\u6570\u636e\uff0c\u63d0\u5347\u6570\u636e\u5e93\u64cd\u4f5c\u6548\u7387\u3002<\/p>\n","protected":false},"author":0,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[101],"tags":[],"class_list":["post-76040","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/76040","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"}],"replies":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/comments?post=76040"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/76040\/revisions"}],"predecessor-version":[{"id":76041,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/76040\/revisions\/76041"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=76040"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=76040"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=76040"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}