{"id":79334,"date":"2024-10-16T12:58:17","date_gmt":"2024-10-16T04:58:17","guid":{"rendered":"https:\/\/server.hk\/cnblog\/79334\/"},"modified":"2024-10-16T12:58:17","modified_gmt":"2024-10-16T04:58:17","slug":"mysql%e6%8c%87%e4%bb%a4-on-delete%ef%bc%88%e5%88%aa%e9%99%a4%e6%99%82%ef%bc%89","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/79334\/","title":{"rendered":"MySQL\u6307\u4ee4: ON DELETE\uff08\u522a\u9664\u6642\uff09"},"content":{"rendered":"<h1 id=\"mysql%e6%8c%87%e4%bb%a4-on-delete%ef%bc%88%e5%88%aa%e9%99%a4%e6%99%82%ef%bc%89-COzUxyBoCw\">MySQL\u6307\u4ee4: ON DELETE\uff08\u522a\u9664\u6642\uff09<\/h1>\n<p>\u5728\u95dc\u806f\u5f0f\u8cc7\u6599\u5eab\u4e2d\uff0c\u8cc7\u6599\u8868\u4e4b\u9593\u7684\u95dc\u806f\u6027\u662f\u975e\u5e38\u91cd\u8981\u7684\u3002MySQL\u4f5c\u70ba\u4e00\u500b\u6d41\u884c\u7684\u8cc7\u6599\u5eab\u7ba1\u7406\u7cfb\u7d71\uff0c\u63d0\u4f9b\u4e86\u591a\u7a2e\u65b9\u5f0f\u4f86\u7ba1\u7406\u9019\u4e9b\u95dc\u806f\u6027\u3002\u5176\u4e2d\uff0c<code>ON DELETE<\/code>\u6307\u4ee4\u662f\u7528\u4f86\u5b9a\u7fa9\u7576\u4e00\u500b\u8cc7\u6599\u884c\u88ab\u522a\u9664\u6642\uff0c\u76f8\u95dc\u8cc7\u6599\u884c\u61c9\u8a72\u5982\u4f55\u8655\u7406\u7684\u95dc\u9375\u6307\u4ee4\u3002\u672c\u6587\u5c07\u6df1\u5165\u63a2\u8a0e<code>ON DELETE<\/code>\u7684\u4e0d\u540c\u9078\u9805\u53ca\u5176\u61c9\u7528\u3002<\/p>\n<h2 id=\"%e4%bb%80%e9%ba%bc%e6%98%afon-delete-COzUxyBoCw\">\u4ec0\u9ebc\u662fON DELETE?<\/h2>\n<p><code>ON DELETE<\/code>\u662f\u7528\u65bc\u5916\u9375\u7d04\u675f\u7684\u4e00\u90e8\u5206\uff0c\u7576\u4e00\u500b\u7236\u8868\u4e2d\u7684\u8cc7\u6599\u88ab\u522a\u9664\u6642\uff0c\u9019\u500b\u6307\u4ee4\u6c7a\u5b9a\u4e86\u5b50\u8868\u4e2d\u76f8\u95dc\u8cc7\u6599\u7684\u884c\u70ba\u3002\u9019\u5c0d\u65bc\u4fdd\u6301\u8cc7\u6599\u7684\u5b8c\u6574\u6027\u548c\u4e00\u81f4\u6027\u81f3\u95dc\u91cd\u8981\u3002<\/p>\n<h2 id=\"on-delete%e7%9a%84%e9%81%b8%e9%a0%85-COzUxyBoCw\">ON DELETE\u7684\u9078\u9805<\/h2>\n<p>MySQL\u63d0\u4f9b\u4e86\u5e7e\u7a2e<code>ON DELETE<\/code>\u7684\u9078\u9805\uff0c\u4e3b\u8981\u5305\u62ec\uff1a<\/p>\n<ul>\n<li><code>CASCADE<\/code><\/li>\n<li><code>SET NULL<\/code><\/li>\n<li><code>NO ACTION<\/code><\/li>\n<li><code>RESTRICT<\/code><\/li>\n<li><code>SET DEFAULT<\/code><\/li>\n<\/ul>\n<h3 id=\"1-cascade-COzUxyBoCw\">1. CASCADE<\/h3>\n<p>\u7576\u4f7f\u7528<code>CASCADE<\/code>\u9078\u9805\u6642\uff0c\u7576\u7236\u8868\u4e2d\u7684\u4e00\u884c\u88ab\u522a\u9664\u6642\uff0c\u6240\u6709\u5728\u5b50\u8868\u4e2d\u8207\u4e4b\u76f8\u95dc\u7684\u884c\u4e5f\u6703\u81ea\u52d5\u88ab\u522a\u9664\u3002\u9019\u5c0d\u65bc\u9700\u8981\u4fdd\u6301\u8cc7\u6599\u4e00\u81f4\u6027\u7684\u60c5\u6cc1\u975e\u5e38\u6709\u7528\u3002<\/p>\n<pre><code>CREATE TABLE orders (\n    order_id INT PRIMARY KEY,\n    customer_id INT,\n    FOREIGN KEY (customer_id) REFERENCES customers(customer_id) ON DELETE CASCADE\n);<\/code><\/pre>\n<p>\u5728\u9019\u500b\u4f8b\u5b50\u4e2d\uff0c\u7576\u4e00\u500b\u5ba2\u6236\u88ab\u522a\u9664\u6642\uff0c\u6240\u6709\u8207\u8a72\u5ba2\u6236\u76f8\u95dc\u7684\u8a02\u55ae\u4e5f\u6703\u88ab\u81ea\u52d5\u522a\u9664\u3002<\/p>\n<h3 id=\"2-set-null-COzUxyBoCw\">2. SET NULL<\/h3>\n<p>\u4f7f\u7528<code>SET NULL<\/code>\u9078\u9805\u6642\uff0c\u7576\u7236\u8868\u4e2d\u7684\u4e00\u884c\u88ab\u522a\u9664\u6642\uff0c\u5b50\u8868\u4e2d\u76f8\u95dc\u7684\u5916\u9375\u6b04\u4f4d\u5c07\u88ab\u8a2d\u7f6e\u70baNULL\u3002\u9019\u5728\u67d0\u4e9b\u60c5\u6cc1\u4e0b\u53ef\u4ee5\u4fdd\u7559\u5b50\u8868\u4e2d\u7684\u8cc7\u6599\uff0c\u4f46\u53bb\u9664\u4e86\u8207\u7236\u8868\u7684\u95dc\u806f\u3002<\/p>\n<pre><code>CREATE TABLE orders (\n    order_id INT PRIMARY KEY,\n    customer_id INT,\n    FOREIGN KEY (customer_id) REFERENCES customers(customer_id) ON DELETE SET NULL\n);<\/code><\/pre>\n<p>\u5728\u9019\u500b\u4f8b\u5b50\u4e2d\uff0c\u7576\u5ba2\u6236\u88ab\u522a\u9664\u6642\uff0c\u6240\u6709\u76f8\u95dc\u7684\u8a02\u55ae\u5c07\u4fdd\u7559\uff0c\u4f46\u5176<code>customer_id<\/code>\u5c07\u88ab\u8a2d\u7f6e\u70baNULL\u3002<\/p>\n<h3 id=\"3-no-action-COzUxyBoCw\">3. NO ACTION<\/h3>\n<p><code>NO ACTION<\/code>\u9078\u9805\u8868\u793a\u5982\u679c\u6709\u4efb\u4f55\u5b50\u8868\u4e2d\u7684\u8cc7\u6599\u8207\u7236\u8868\u4e2d\u7684\u8cc7\u6599\u76f8\u95dc\u806f\uff0c\u5247\u4e0d\u5141\u8a31\u522a\u9664\u7236\u8868\u4e2d\u7684\u8cc7\u6599\u3002\u9019\u662f\u6700\u56b4\u683c\u7684\u9078\u9805\uff0c\u78ba\u4fdd\u4e86\u8cc7\u6599\u7684\u5b8c\u6574\u6027\u3002<\/p>\n<pre><code>CREATE TABLE orders (\n    order_id INT PRIMARY KEY,\n    customer_id INT,\n    FOREIGN KEY (customer_id) REFERENCES customers(customer_id) ON DELETE NO ACTION\n);<\/code><\/pre>\n<h3 id=\"4-restrict-COzUxyBoCw\">4. RESTRICT<\/h3>\n<p><code>RESTRICT<\/code>\u8207<code>NO ACTION<\/code>\u985e\u4f3c\uff0c\u4f46\u5728\u57f7\u884c\u522a\u9664\u64cd\u4f5c\u6642\u6703\u7acb\u5373\u6aa2\u67e5\u7d04\u675f\u689d\u4ef6\u3002\u5982\u679c\u6709\u4efb\u4f55\u76f8\u95dc\u7684\u5b50\u8868\u8cc7\u6599\uff0c\u5247\u6703\u963b\u6b62\u522a\u9664\u64cd\u4f5c\u3002<\/p>\n<h3 id=\"5-set-default-COzUxyBoCw\">5. SET DEFAULT<\/h3>\n<p>\u4f7f\u7528<code>SET DEFAULT<\/code>\u9078\u9805\u6642\uff0c\u7576\u7236\u8868\u4e2d\u7684\u4e00\u884c\u88ab\u522a\u9664\u6642\uff0c\u5b50\u8868\u4e2d\u76f8\u95dc\u7684\u5916\u9375\u6b04\u4f4d\u5c07\u88ab\u8a2d\u7f6e\u70ba\u5176\u9810\u8a2d\u503c\u3002\u9019\u5728\u67d0\u4e9b\u60c5\u6cc1\u4e0b\u53ef\u4ee5\u4fdd\u6301\u8cc7\u6599\u7684\u5b8c\u6574\u6027\uff0c\u540c\u6642\u5141\u8a31\u67d0\u4e9b\u9748\u6d3b\u6027\u3002<\/p>\n<pre><code>CREATE TABLE orders (\n    order_id INT PRIMARY KEY,\n    customer_id INT DEFAULT 0,\n    FOREIGN KEY (customer_id) REFERENCES customers(customer_id) ON DELETE SET DEFAULT\n);<\/code><\/pre>\n<h2 id=\"%e7%b8%bd%e7%b5%90-COzUxyBoCw\">\u7e3d\u7d50<\/h2>\n<p>\u5728MySQL\u4e2d\uff0c<code>ON DELETE<\/code>\u6307\u4ee4\u662f\u7ba1\u7406\u8cc7\u6599\u8868\u4e4b\u9593\u95dc\u806f\u6027\u7684\u91cd\u8981\u5de5\u5177\u3002\u901a\u904e\u9078\u64c7\u9069\u7576\u7684\u9078\u9805\uff0c\u5982<code>CASCADE<\/code>\u3001<code>SET NULL<\/code>\u3001<code>NO ACTION<\/code>\u3001<code>RESTRICT<\/code>\u548c<code>SET DEFAULT<\/code>\uff0c\u958b\u767c\u8005\u53ef\u4ee5\u6709\u6548\u5730\u63a7\u5236\u8cc7\u6599\u7684\u5b8c\u6574\u6027\u548c\u4e00\u81f4\u6027\u3002\u4e86\u89e3\u9019\u4e9b\u9078\u9805\u7684\u4f7f\u7528\u60c5\u5883\uff0c\u5c0d\u65bc\u8a2d\u8a08\u7a69\u5065\u7684\u8cc7\u6599\u5eab\u67b6\u69cb\u81f3\u95dc\u91cd\u8981\u3002<\/p>\n<p>\u5982\u679c\u60a8\u6b63\u5728\u5c0b\u627e\u9ad8\u6548\u7684 <a href=\"https:\/\/server.hk\">\u9999\u6e2fVPS<\/a> \u89e3\u6c7a\u65b9\u6848\uff0cServer.HK \u63d0\u4f9b\u591a\u7a2e\u9078\u64c7\u4ee5\u6eff\u8db3\u60a8\u7684\u9700\u6c42\uff0c\u7121\u8ad6\u662f\u8cc7\u6599\u5eab\u7ba1\u7406\u9084\u662f\u5176\u4ed6\u61c9\u7528\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4e86\u89e3MySQL\u4e2d\u7684ON DELETE\u6307\u4ee4\uff0c\u638c\u63e1\u5982\u4f55\u5728\u522a\u9664\u64cd\u4f5c\u4e2d\u7dad\u8b77\u6578\u64da\u5b8c\u6574\u6027\u548c\u95dc\u806f\u6027\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-79334","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/79334","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=79334"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/79334\/revisions"}],"predecessor-version":[{"id":79335,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/79334\/revisions\/79335"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=79334"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=79334"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=79334"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}