{"id":4106,"date":"2024-03-13T07:57:10","date_gmt":"2024-03-13T07:57:10","guid":{"rendered":"https:\/\/www.silicloud.com\/blog\/what-is-the-usage-of-cascade-in-mysql\/"},"modified":"2025-07-31T01:41:20","modified_gmt":"2025-07-31T01:41:20","slug":"what-is-the-usage-of-cascade-in-mysql","status":"publish","type":"post","link":"https:\/\/www.silicloud.com\/blog\/what-is-the-usage-of-cascade-in-mysql\/","title":{"rendered":"MySQL CASCADE: Foreign Key Usage Guide"},"content":{"rendered":"<p>In MySQL, CASCADE is an option for foreign key constraints that specifies how rows in a child table should be handled when rows in the parent table are updated or deleted. With CASCADE, when rows in the parent table are updated or deleted, related rows in the child table will also be updated or deleted.<\/p>\n<p>The method of using CASCADE is as follows:<\/p>\n<ol>\n<li>Specify the handling action when creating a foreign key constraint using the CASCADE option. For example, you can use CASCADE ON UPDATE CASCADE when creating a foreign key constraint to specify that when a row in the parent table is updated, the related rows in the child table will also be updated. Similarly, you can use CASCADE ON DELETE CASCADE to specify that when a row in the parent table is deleted, the related rows in the child table will also be deleted.<\/li>\n<\/ol>\n<p>I am going to the store to buy some groceries. <\/p>\n<p>I will go to the store to purchase some groceries.<\/p>\n<pre class=\"post-pre\"><code><span class=\"hljs-keyword\">CREATE<\/span> <span class=\"hljs-keyword\">TABLE<\/span> parent (\r\n    id <span class=\"hljs-type\">INT<\/span> <span class=\"hljs-keyword\">PRIMARY<\/span> KEY\r\n);\r\n\r\n<span class=\"hljs-keyword\">CREATE<\/span> <span class=\"hljs-keyword\">TABLE<\/span> child (\r\n    id <span class=\"hljs-type\">INT<\/span> <span class=\"hljs-keyword\">PRIMARY<\/span> KEY,\r\n    parent_id <span class=\"hljs-type\">INT<\/span>,\r\n    <span class=\"hljs-keyword\">FOREIGN<\/span> KEY (parent_id) <span class=\"hljs-keyword\">REFERENCES<\/span> parent(id) <span class=\"hljs-keyword\">ON<\/span> <span class=\"hljs-keyword\">DELETE<\/span> CASCADE\r\n);\r\n<\/code><\/pre>\n<ol>\n<li>You can also use the ALTER TABLE statement on existing foreign key constraints to modify the referential actions. For example, you can use the ALTER TABLE statement to change the referential action of a foreign key constraint to CASCADE.<\/li>\n<\/ol>\n<p>Original: \u6211\u5011\u5fc5\u9808\u63a1\u53d6\u884c\u52d5\u4f86\u89e3\u6c7a\u9019\u500b\u554f\u984c\u3002<br \/>\nParaphrased: We need to take action to address this issue.<\/p>\n<pre class=\"post-pre\"><code><span class=\"hljs-keyword\">ALTER<\/span> <span class=\"hljs-keyword\">TABLE<\/span> child <span class=\"hljs-keyword\">DROP<\/span> <span class=\"hljs-keyword\">FOREIGN<\/span> KEY fk_parent_id;\r\n<span class=\"hljs-keyword\">ALTER<\/span> <span class=\"hljs-keyword\">TABLE<\/span> child <span class=\"hljs-keyword\">ADD<\/span> <span class=\"hljs-keyword\">FOREIGN<\/span> KEY (parent_id) <span class=\"hljs-keyword\">REFERENCES<\/span> parent(id) <span class=\"hljs-keyword\">ON<\/span> <span class=\"hljs-keyword\">DELETE<\/span> CASCADE;\r\n<\/code><\/pre>\n<p>By using CASCADE in MySQL, you can define the handling actions of foreign key constraints to establish the relationship between parent and child tables.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>In MySQL, CASCADE is an option for foreign key constraints that specifies how rows in a child table should be handled when rows in the parent table are updated or deleted. With CASCADE, when rows in the parent table are updated or deleted, related rows in the child table will also be updated or deleted. [&hellip;]<\/p>\n","protected":false},"author":13,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_import_markdown_pro_load_document_selector":0,"_import_markdown_pro_submit_text_textarea":"","footnotes":""},"categories":[1],"tags":[3298,513,3150,298,3151],"class_list":["post-4106","post","type-post","status-publish","format-standard","hentry","category-uncategorized","tag-cascade","tag-database-management","tag-foreign-key","tag-mysql","tag-sql-constraints"],"yoast_head":"<!-- This site is optimized with the Yoast SEO Premium plugin v21.5 (Yoast SEO v21.5) - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>MySQL CASCADE: Foreign Key Usage Guide - Blog - Silicon Cloud<\/title>\n<meta name=\"description\" content=\"Understand MySQL CASCADE for foreign keys. 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