{"id":180188,"date":"2024-11-09T08:08:19","date_gmt":"2024-11-09T00:08:19","guid":{"rendered":"https:\/\/server.hk\/cnblog\/180188\/"},"modified":"2024-11-09T08:08:20","modified_gmt":"2024-11-09T00:08:20","slug":"%e5%88%aa%e9%99%a4sql%e7%b4%84%e6%9d%9f%e7%9a%84%e6%96%b9%e6%b3%95","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/180188\/","title":{"rendered":"\u522a\u9664SQL\u7d04\u675f\u7684\u65b9\u6cd5"},"content":{"rendered":"<h1 id=\"%e5%88%aa%e9%99%a4sql%e7%b4%84%e6%9d%9f%e7%9a%84%e6%96%b9%e6%b3%95-jExwREMAjw\">\u522a\u9664SQL\u7d04\u675f\u7684\u65b9\u6cd5<\/h1>\n<p>\u5728\u8cc7\u6599\u5eab\u7ba1\u7406\u4e2d\uff0cSQL\u7d04\u675f\uff08Constraints\uff09\u662f\u7528\u4f86\u9650\u5236\u8cc7\u6599\u8868\u4e2d\u8cc7\u6599\u7684\u5b8c\u6574\u6027\u548c\u4e00\u81f4\u6027\u7684\u91cd\u8981\u5de5\u5177\u3002\u5e38\u898b\u7684\u7d04\u675f\u985e\u578b\u5305\u62ec\u4e3b\u9375\u7d04\u675f\u3001\u5916\u9375\u7d04\u675f\u3001\u552f\u4e00\u7d04\u675f\u548c\u6aa2\u67e5\u7d04\u675f\u7b49\u3002\u7136\u800c\uff0c\u96a8\u8457\u696d\u52d9\u9700\u6c42\u7684\u8b8a\u5316\uff0c\u53ef\u80fd\u9700\u8981\u522a\u9664\u67d0\u4e9b\u7d04\u675f\u3002\u672c\u6587\u5c07\u63a2\u8a0e\u5982\u4f55\u5728SQL\u4e2d\u522a\u9664\u7d04\u675f\uff0c\u4e26\u63d0\u4f9b\u76f8\u95dc\u7684\u7bc4\u4f8b\u548c\u6ce8\u610f\u4e8b\u9805\u3002<\/p>\n<h2 id=\"sql%e7%b4%84%e6%9d%9f%e7%9a%84%e9%a1%9e%e5%9e%8b-jExwREMAjw\">SQL\u7d04\u675f\u7684\u985e\u578b<\/h2>\n<p>\u5728\u6df1\u5165\u522a\u9664\u7d04\u675f\u7684\u65b9\u6cd5\u4e4b\u524d\uff0c\u4e86\u89e3\u4e0d\u540c\u985e\u578b\u7684SQL\u7d04\u675f\u662f\u975e\u5e38\u91cd\u8981\u7684\u3002\u4ee5\u4e0b\u662f\u5e7e\u7a2e\u5e38\u898b\u7684\u7d04\u675f\u985e\u578b\uff1a<\/p>\n<ul>\n<li><strong>\u4e3b\u9375\u7d04\u675f\uff08PRIMARY KEY\uff09<\/strong>\uff1a\u78ba\u4fdd\u8cc7\u6599\u8868\u4e2d\u7684\u6bcf\u4e00\u884c\u90fd\u662f\u552f\u4e00\u7684\uff0c\u4e26\u4e14\u4e0d\u5141\u8a31\u7a7a\u503c\u3002<\/li>\n<li><strong>\u5916\u9375\u7d04\u675f\uff08FOREIGN KEY\uff09<\/strong>\uff1a\u7528\u65bc\u5efa\u7acb\u5169\u500b\u8cc7\u6599\u8868\u4e4b\u9593\u7684\u95dc\u806f\uff0c\u78ba\u4fdd\u8cc7\u6599\u7684\u53c3\u7167\u5b8c\u6574\u6027\u3002<\/li>\n<li><strong>\u552f\u4e00\u7d04\u675f\uff08UNIQUE\uff09<\/strong>\uff1a\u78ba\u4fdd\u67d0\u4e00\u5217\u7684\u6240\u6709\u503c\u90fd\u662f\u552f\u4e00\u7684\uff0c\u4f46\u5141\u8a31\u7a7a\u503c\u3002<\/li>\n<li><strong>\u6aa2\u67e5\u7d04\u675f\uff08CHECK\uff09<\/strong>\uff1a\u7528\u65bc\u9650\u5236\u67d0\u4e00\u5217\u7684\u503c\u5fc5\u9808\u6eff\u8db3\u7279\u5b9a\u689d\u4ef6\u3002<\/li>\n<\/ul>\n<h2 id=\"%e5%88%aa%e9%99%a4%e7%b4%84%e6%9d%9f%e7%9a%84%e5%9f%ba%e6%9c%ac%e8%aa%9e%e6%b3%95-jExwREMAjw\">\u522a\u9664\u7d04\u675f\u7684\u57fa\u672c\u8a9e\u6cd5<\/h2>\n<p>\u522a\u9664SQL\u7d04\u675f\u7684\u57fa\u672c\u8a9e\u6cd5\u5982\u4e0b\uff1a<\/p>\n<pre><code>ALTER TABLE \u8868\u540d DROP CONSTRAINT \u7d04\u675f\u540d;<\/code><\/pre>\n<p>\u5728\u9019\u88e1\uff0c<code>\u8868\u540d<\/code>\u662f\u60a8\u8981\u4fee\u6539\u7684\u8cc7\u6599\u8868\u540d\u7a31\uff0c\u800c<code>\u7d04\u675f\u540d<\/code>\u662f\u60a8\u5e0c\u671b\u522a\u9664\u7684\u7d04\u675f\u540d\u7a31\u3002<\/p>\n<h2 id=\"%e5%88%aa%e9%99%a4%e4%b8%8d%e5%90%8c%e9%a1%9e%e5%9e%8b%e7%9a%84%e7%b4%84%e6%9d%9f-jExwREMAjw\">\u522a\u9664\u4e0d\u540c\u985e\u578b\u7684\u7d04\u675f<\/h2>\n<h3 id=\"1-%e5%88%aa%e9%99%a4%e4%b8%bb%e9%8d%b5%e7%b4%84%e6%9d%9f-jExwREMAjw\">1. \u522a\u9664\u4e3b\u9375\u7d04\u675f<\/h3>\n<p>\u8981\u522a\u9664\u4e3b\u9375\u7d04\u675f\uff0c\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b\u8a9e\u6cd5\uff1a<\/p>\n<pre><code>ALTER TABLE \u8868\u540d DROP PRIMARY KEY;<\/code><\/pre>\n<p>\u4f8b\u5982\uff0c\u5047\u8a2d\u6709\u4e00\u500b\u540d\u70ba <code>users<\/code> \u7684\u8cc7\u6599\u8868\uff0c\u60a8\u53ef\u4ee5\u9019\u6a23\u522a\u9664\u4e3b\u9375\u7d04\u675f\uff1a<\/p>\n<pre><code>ALTER TABLE users DROP PRIMARY KEY;<\/code><\/pre>\n<h3 id=\"2-%e5%88%aa%e9%99%a4%e5%a4%96%e9%8d%b5%e7%b4%84%e6%9d%9f-jExwREMAjw\">2. \u522a\u9664\u5916\u9375\u7d04\u675f<\/h3>\n<p>\u522a\u9664\u5916\u9375\u7d04\u675f\u9700\u8981\u6307\u5b9a\u7d04\u675f\u7684\u540d\u7a31\uff0c\u8a9e\u6cd5\u5982\u4e0b\uff1a<\/p>\n<pre><code>ALTER TABLE \u8868\u540d DROP FOREIGN KEY \u7d04\u675f\u540d;<\/code><\/pre>\n<p>\u4f8b\u5982\uff0c\u5047\u8a2d\u60a8\u6709\u4e00\u500b\u540d\u70ba <code>orders<\/code> \u7684\u8cc7\u6599\u8868\uff0c\u4e26\u4e14\u8981\u522a\u9664\u540d\u70ba <code>fk_user_id<\/code> \u7684\u5916\u9375\u7d04\u675f\uff1a<\/p>\n<pre><code>ALTER TABLE orders DROP FOREIGN KEY fk_user_id;<\/code><\/pre>\n<h3 id=\"3-%e5%88%aa%e9%99%a4%e5%94%af%e4%b8%80%e7%b4%84%e6%9d%9f-jExwREMAjw\">3. \u522a\u9664\u552f\u4e00\u7d04\u675f<\/h3>\n<p>\u522a\u9664\u552f\u4e00\u7d04\u675f\u7684\u8a9e\u6cd5\u8207\u522a\u9664\u5916\u9375\u7d04\u675f\u985e\u4f3c\uff1a<\/p>\n<pre><code>ALTER TABLE \u8868\u540d DROP INDEX \u7d04\u675f\u540d;<\/code><\/pre>\n<p>\u4f8b\u5982\uff0c\u5047\u8a2d\u60a8\u8981\u522a\u9664 <code>users<\/code> \u8cc7\u6599\u8868\u4e2d\u7684\u552f\u4e00\u7d04\u675f <code>unique_email<\/code>\uff1a<\/p>\n<pre><code>ALTER TABLE users DROP INDEX unique_email;<\/code><\/pre>\n<h3 id=\"4-%e5%88%aa%e9%99%a4%e6%aa%a2%e6%9f%a5%e7%b4%84%e6%9d%9f-jExwREMAjw\">4. \u522a\u9664\u6aa2\u67e5\u7d04\u675f<\/h3>\n<p>\u522a\u9664\u6aa2\u67e5\u7d04\u675f\u7684\u8a9e\u6cd5\u5982\u4e0b\uff1a<\/p>\n<pre><code>ALTER TABLE \u8868\u540d DROP CHECK \u7d04\u675f\u540d;<\/code><\/pre>\n<p>\u4f8b\u5982\uff0c\u5047\u8a2d\u60a8\u8981\u522a\u9664 <code>products<\/code> \u8cc7\u6599\u8868\u4e2d\u7684\u6aa2\u67e5\u7d04\u675f <code>check_price<\/code>\uff1a<\/p>\n<pre><code>ALTER TABLE products DROP CHECK check_price;<\/code><\/pre>\n<h2 id=\"%e6%b3%a8%e6%84%8f%e4%ba%8b%e9%a0%85-jExwREMAjw\">\u6ce8\u610f\u4e8b\u9805<\/h2>\n<p>\u5728\u522a\u9664\u7d04\u675f\u4e4b\u524d\uff0c\u8acb\u52d9\u5fc5\u8003\u616e\u4ee5\u4e0b\u5e7e\u9ede\uff1a<\/p>\n<ul>\n<li>\u522a\u9664\u7d04\u675f\u53ef\u80fd\u6703\u5f71\u97ff\u8cc7\u6599\u7684\u5b8c\u6574\u6027\uff0c\u8acb\u78ba\u4fdd\u5728\u522a\u9664\u4e4b\u524d\u9032\u884c\u5145\u5206\u7684\u6e2c\u8a66\u3002<\/li>\n<li>\u67d0\u4e9b\u8cc7\u6599\u5eab\u7cfb\u7d71\u53ef\u80fd\u5c0d\u7d04\u675f\u7684\u522a\u9664\u6709\u7279\u5b9a\u7684\u9650\u5236\u6216\u8981\u6c42\uff0c\u8acb\u53c3\u8003\u76f8\u95dc\u7684\u8cc7\u6599\u5eab\u6587\u6a94\u3002<\/li>\n<li>\u5728\u522a\u9664\u7d04\u675f\u4e4b\u524d\uff0c\u5efa\u8b70\u5099\u4efd\u8cc7\u6599\u5eab\uff0c\u4ee5\u9632\u6b62\u610f\u5916\u640d\u5931\u3002<\/li>\n<\/ul>\n<h2 id=\"%e7%b8%bd%e7%b5%90-jExwREMAjw\">\u7e3d\u7d50<\/h2>\n<p>\u522a\u9664SQL\u7d04\u675f\u662f\u4e00\u500b\u91cd\u8981\u7684\u64cd\u4f5c\uff0c\u80fd\u5920\u5e6b\u52a9\u8cc7\u6599\u5eab\u7ba1\u7406\u54e1\u6839\u64da\u696d\u52d9\u9700\u6c42\u8abf\u6574\u8cc7\u6599\u8868\u7684\u7d50\u69cb\u3002\u7121\u8ad6\u662f\u522a\u9664\u4e3b\u9375\u3001\u5916\u9375\u3001\u552f\u4e00\u9084\u662f\u6aa2\u67e5\u7d04\u675f\uff0c\u4e86\u89e3\u6b63\u78ba\u7684\u8a9e\u6cd5\u548c\u6ce8\u610f\u4e8b\u9805\u90fd\u662f\u81f3\u95dc\u91cd\u8981\u7684\u3002\u82e5\u60a8\u9700\u8981\u9032\u4e00\u6b65\u4e86\u89e3\u5982\u4f55\u7ba1\u7406\u60a8\u7684\u8cc7\u6599\u5eab\u6216\u5c0b\u627e\u5408\u9069\u7684 <a href=\"https:\/\/server.hk\">\u9999\u6e2fVPS<\/a> \u89e3\u6c7a\u65b9\u6848\uff0c\u8acb\u8a2a\u554f\u6211\u5011\u7684\u7db2\u7ad9\u4ee5\u7372\u53d6\u66f4\u591a\u8cc7\u8a0a\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4e86\u89e3\u5982\u4f55\u6709\u6548\u522a\u9664SQL\u7d04\u675f\uff0c\u78ba\u4fdd\u6578\u64da\u5b8c\u6574\u6027\u8207\u9748\u6d3b\u6027\uff0c\u63d0\u5347\u6578\u64da\u5eab\u7ba1\u7406\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-180188","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/180188","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=180188"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/180188\/revisions"}],"predecessor-version":[{"id":180189,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/180188\/revisions\/180189"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=180188"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=180188"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=180188"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}