{"id":28466,"date":"2025-05-21T15:48:24","date_gmt":"2025-05-21T08:48:24","guid":{"rendered":"https:\/\/interdata.vn\/blog\/?p=28466"},"modified":"2025-06-12T16:51:35","modified_gmt":"2025-06-12T09:51:35","slug":"foreign-key-la-gi","status":"publish","type":"post","link":"https:\/\/interdata.vn\/blog\/foreign-key-la-gi\/","title":{"rendered":"Foreign Key l\u00e0 g\u00ec trong DBMS? V\u00ed d\u1ee5 &#038; C\u00fa ph\u00e1p kh\u00f3a ngo\u1ea1i \u0111\u1ea7y \u0111\u1ee7"},"content":{"rendered":"<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_85 counter-hierarchy ez-toc-counter ez-toc-white ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">N\u1ed8I DUNG<\/p>\n<span class=\"ez-toc-title-toggle\"><a href=\"#\" class=\"ez-toc-pull-right ez-toc-btn ez-toc-btn-xs ez-toc-btn-default ez-toc-toggle\" aria-label=\"Toggle Table of Content\"><span class=\"ez-toc-js-icon-con\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #999;color:#999\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #999;color:#999\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/span><\/a><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1 eztoc-toggle-hide-by-default' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/interdata.vn\/blog\/foreign-key-la-gi\/#Foreign-Key-la-gi\" >Foreign Key l\u00e0 g\u00ec?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/interdata.vn\/blog\/foreign-key-la-gi\/#Vi-du-minh-hoa-ve-Foreign-Key\" >V\u00ed d\u1ee5 minh h\u1ecda v\u1ec1 Foreign Key<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/interdata.vn\/blog\/foreign-key-la-gi\/#Loi-ich-cua-Foreign-Key-trong-DBMS\" >L\u1ee3i \u00edch c\u1ee7a Foreign Key trong DBMS<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/interdata.vn\/blog\/foreign-key-la-gi\/#Dam-bao-tinh-toan-ven-du-lieu\" >\u0110\u1ea3m b\u1ea3o t\u00ednh to\u00e0n v\u1eb9n d\u1eef li\u1ec7u<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/interdata.vn\/blog\/foreign-key-la-gi\/#Thiet-lap-moi-quan-he-ro-rang\" >Thi\u1ebft l\u1eadp m\u1ed1i quan h\u1ec7 r\u00f5 r\u00e0ng<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/interdata.vn\/blog\/foreign-key-la-gi\/#Toi-uu-hoa-truy-van\" >T\u1ed1i \u01b0u h\u00f3a truy v\u1ea5n<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/interdata.vn\/blog\/foreign-key-la-gi\/#Ho-tro-bao-tri-co-so-du-lieu\" >H\u1ed7 tr\u1ee3 b\u1ea3o tr\u00ec c\u01a1 s\u1edf d\u1eef li\u1ec7u<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"https:\/\/interdata.vn\/blog\/foreign-key-la-gi\/#Tang-cuong-bao-mat-du-lieu\" >T\u0103ng c\u01b0\u1eddng b\u1ea3o m\u1eadt d\u1eef li\u1ec7u<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-9\" href=\"https:\/\/interdata.vn\/blog\/foreign-key-la-gi\/#Cu-phap-tao-xoa-Foreign-Key-trong-DBMS\" >C\u00fa ph\u00e1p t\u1ea1o, x\u00f3a Foreign Key trong DBMS<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-10\" href=\"https:\/\/interdata.vn\/blog\/foreign-key-la-gi\/#Cau-hoi-thuong-gap-ve-Foreign-Key\" >C\u00e2u h\u1ecfi th\u01b0\u1eddng g\u1eb7p v\u1ec1 Foreign Key<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-11\" href=\"https:\/\/interdata.vn\/blog\/foreign-key-la-gi\/#Foreign-Key-dung-de-lam-gi-trong-co-so-du-lieu\" >Foreign Key d\u00f9ng \u0111\u1ec3 l\u00e0m g\u00ec trong c\u01a1 s\u1edf d\u1eef li\u1ec7u?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-12\" href=\"https:\/\/interdata.vn\/blog\/foreign-key-la-gi\/#Mot-bang-trong-database-co-the-co-nhieu-hon-mot-Khoa-ngoai-duoc-khong\" >M\u1ed9t b\u1ea3ng trong database c\u00f3 th\u1ec3 c\u00f3 nhi\u1ec1u h\u01a1n m\u1ed9t Kh\u00f3a ngo\u1ea1i \u0111\u01b0\u1ee3c kh\u00f4ng?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-13\" href=\"https:\/\/interdata.vn\/blog\/foreign-key-la-gi\/#Khoa-ngoai-co-bat-buoc-phai-chua-gia-tri-NOT-NULL-khong\" >Kh\u00f3a ngo\u1ea1i c\u00f3 b\u1eaft bu\u1ed9c ph\u1ea3i ch\u1ee9a gi\u00e1 tr\u1ecb (NOT NULL) kh\u00f4ng?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-14\" href=\"https:\/\/interdata.vn\/blog\/foreign-key-la-gi\/#Khi-thiet-ke-database-khi-nao-nen-su-dung-Khoa-ngoai\" >Khi thi\u1ebft k\u1ebf database, khi n\u00e0o n\u00ean s\u1eed d\u1ee5ng Kh\u00f3a ngo\u1ea1i?<\/a><\/li><\/ul><\/li><\/ul><\/nav><\/div>\n<p>Trong thi\u1ebft k\u1ebf c\u01a1 s\u1edf d\u1eef li\u1ec7u, Foreign Key (Kh\u00f3a ngo\u1ea1i) \u0111\u00f3ng vai tr\u00f2 quan tr\u1ecdng gi\u00fap duy tr\u00ec t\u00ednh nh\u1ea5t qu\u00e1n v\u00e0 to\u00e0n v\u1eb9n d\u1eef li\u1ec7u. \u0110\u00e2y l\u00e0 m\u1ed9t trong nh\u1eefng th\u00e0nh ph\u1ea7n then ch\u1ed1t gi\u00fap thi\u1ebft l\u1eadp m\u1ed1i quan h\u1ec7 gi\u1eefa c\u00e1c b\u1ea3ng, t\u1eeb \u0111\u00f3 t\u1ed1i \u01b0u h\u00f3a thao t\u00e1c <a href=\"https:\/\/interdata.vn\/blog\/query-la-gi\/\">truy v\u1ea5n<\/a> v\u00e0 n\u00e2ng cao hi\u1ec7u qu\u1ea3 qu\u1ea3n l\u00fd d\u1eef li\u1ec7u. B\u00e0i vi\u1ebft d\u01b0\u1edbi \u0111\u00e2y t\u1eeb InterData s\u1ebd gi\u00fap b\u1ea1n hi\u1ec3u r\u00f5 <a href=\"https:\/\/interdata.vn\/blog\/foreign-key-la-gi\/\"><strong>Foreign Key l\u00e0 g\u00ec<\/strong><\/a>, c\u00fa ph\u00e1p s\u1eed d\u1ee5ng, l\u1ee3i \u00edch th\u1ef1c ti\u1ec5n trong <a href=\"https:\/\/interdata.vn\/blog\/he-quan-tri-co-so-du-lieu-la-gi\/\">h\u1ec7 qu\u1ea3n tr\u1ecb c\u01a1 s\u1edf d\u1eef li\u1ec7u<\/a> v\u00e0 v\u00ed d\u1ee5 minh h\u1ecda \u0111\u1ec3 b\u1ea1n hi\u1ec3u s\u00e2u h\u01a1n v\u1ec1 kh\u00f3a ngo\u1ea1i.<\/p>\n<h2><span class=\"ez-toc-section\" id=\"Foreign-Key-la-gi\"><\/span><span>Foreign Key l\u00e0 g\u00ec?<\/span><span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p><strong>Kh\u00f3a ngo\u1ea1i (Foreign Key &#8211; FK) l\u00e0 m\u1ed9t ho\u1eb7c t\u1eadp h\u1ee3p c\u00e1c c\u1ed9t trong m\u1ed9t b\u1ea3ng, c\u00f3 gi\u00e1 tr\u1ecb tham chi\u1ebfu \u0111\u1ebfn <a href=\"https:\/\/interdata.vn\/blog\/khoa-chinh-la-gi\/\">kh\u00f3a ch\u00ednh<\/a> (Primary Key) ho\u1eb7c kh\u00f3a \u1ee9ng vi\u00ean (Candidate Key) c\u1ee7a m\u1ed9t b\u1ea3ng kh\u00e1c trong c\u00f9ng c\u01a1 s\u1edf d\u1eef li\u1ec7u quan h\u1ec7<\/strong>. M\u1ee5c \u0111\u00edch ch\u00ednh c\u1ee7a kh\u00f3a ngo\u1ea1i l\u00e0 thi\u1ebft l\u1eadp v\u00e0 duy tr\u00ec m\u1ed1i quan h\u1ec7 gi\u1eefa c\u00e1c b\u1ea3ng, gi\u00fap li\u00ean k\u1ebft d\u1eef li\u1ec7u c\u00f3 li\u00ean quan \u0111\u01b0\u1ee3c l\u01b0u tr\u1eef \u1edf c\u00e1c b\u1ea3ng ri\u00eang bi\u1ec7t.<\/p>\n<p>Kh\u00f3a ngo\u1ea1i \u0111\u00f3ng vai tr\u00f2 quan tr\u1ecdng trong vi\u1ec7c \u0111\u1ea3m b\u1ea3o t\u00ednh to\u00e0n v\u1eb9n tham chi\u1ebfu (referential integrity), t\u1ee9c l\u00e0 ng\u0103n ch\u1eb7n c\u00e1c thao t\u00e1c d\u1eef li\u1ec7u b\u1ea5t h\u1ee3p l\u1ec7 l\u00e0m ph\u00e1 v\u1ee1 m\u1ed1i li\u00ean k\u1ebft gi\u1eefa c\u00e1c b\u1ea3ng. V\u00ed d\u1ee5, m\u1ed9t gi\u00e1 tr\u1ecb kh\u00f3a ngo\u1ea1i trong b\u1ea3ng con ph\u1ea3i t\u1ed3n t\u1ea1i trong b\u1ea3ng cha ho\u1eb7c c\u00f3 th\u1ec3 l\u00e0 NULL n\u1ebfu \u0111\u01b0\u1ee3c ph\u00e9p.<\/p>\n<figure id=\"attachment_28931\" aria-describedby=\"caption-attachment-28931\" style=\"width: 800px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/05\/Foreign-Key-la-gi-1.jpg\" alt=\" Foreign Key l\u00e0 g\u00ec?\" width=\"800\" height=\"500\" class=\"size-full wp-image-28931\" title=\"\" srcset=\"https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/05\/Foreign-Key-la-gi-1.jpg 800w, https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/05\/Foreign-Key-la-gi-1-300x188.jpg 300w, https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/05\/Foreign-Key-la-gi-1-768x480.jpg 768w, https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/05\/Foreign-Key-la-gi-1-750x469.jpg 750w\" sizes=\"auto, (max-width: 800px) 100vw, 800px\" \/><figcaption id=\"caption-attachment-28931\" class=\"wp-caption-text\">Foreign Key l\u00e0 g\u00ec?<\/figcaption><\/figure>\n<p>Ngo\u00e0i ra, kh\u00f3a ngo\u1ea1i c\u00f2n gi\u00fap <strong>b\u1ea3o v\u1ec7 d\u1eef li\u1ec7u kh\u1ecfi s\u1ef1 kh\u00f4ng nh\u1ea5t qu\u00e1n<\/strong>, tr\u00e1nh vi\u1ec7c t\u1ea1o ra c\u00e1c b\u1ea3n ghi \u201cm\u1ed3 c\u00f4i\u201d trong b\u1ea3ng con kh\u00f4ng c\u00f3 b\u1ea3n ghi t\u01b0\u01a1ng \u1ee9ng trong b\u1ea3ng cha. M\u1ed9t b\u1ea3ng c\u00f3 th\u1ec3 c\u00f3 nhi\u1ec1u kh\u00f3a ngo\u1ea1i, m\u1ed7i kh\u00f3a ngo\u1ea1i c\u00f3 th\u1ec3 tham chi\u1ebfu \u0111\u1ebfn kh\u00f3a ch\u00ednh c\u1ee7a c\u00e1c b\u1ea3ng kh\u00e1c nhau.<\/p>\n<p>Kh\u00f3a ngo\u1ea1i l\u00e0 th\u00e0nh ph\u1ea7n then ch\u1ed1t trong c\u01a1 s\u1edf d\u1eef li\u1ec7u quan h\u1ec7 \u0111\u1ec3 <strong>t\u1ea1o li\u00ean k\u1ebft gi\u1eefa c\u00e1c b\u1ea3ng<\/strong>, \u0111\u1ea3m b\u1ea3o t\u00ednh to\u00e0n v\u1eb9n v\u00e0 nh\u1ea5t qu\u00e1n d\u1eef li\u1ec7u, \u0111\u1ed3ng th\u1eddi h\u1ed7 tr\u1ee3 t\u1ed1i \u01b0u truy v\u1ea5n v\u00e0 qu\u1ea3n l\u00fd d\u1eef li\u1ec7u hi\u1ec7u qu\u1ea3<\/p>\n<h2><span class=\"ez-toc-section\" id=\"Vi-du-minh-hoa-ve-Foreign-Key\"><\/span><span>V\u00ed d\u1ee5 minh h\u1ecda v\u1ec1 Foreign Key<\/span><span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p><span><strong>V\u00ed d\u1ee5 1:<\/strong><\/span><\/p>\n<p><span>H\u00e3y t\u01b0\u1edfng t\u01b0\u1ee3ng b\u1ea1n c\u00f3 hai b\u1ea3ng trong database: <code>KhachHang<\/code> (l\u01b0u th\u00f4ng tin kh\u00e1ch h\u00e0ng) v\u00e0 <code>DonHang<\/code> (l\u01b0u th\u00f4ng tin \u0111\u01a1n h\u00e0ng). B\u1ea3ng <code>KhachHang<\/code> c\u00f3 c\u1ed9t <code>MaKhachHang<\/code> l\u00e0 Kh\u00f3a ch\u00ednh \u0111\u1ec3 \u0111\u1ecbnh danh t\u1eebng kh\u00e1ch h\u00e0ng.<\/span><\/p>\n<p><span>\u0110\u1ec3 bi\u1ebft m\u1ed7i \u0111\u01a1n h\u00e0ng thu\u1ed9c v\u1ec1 kh\u00e1ch h\u00e0ng n\u00e0o, ch\u00fang ta th\u00eam c\u1ed9t <code>MaKhachHang<\/code> v\u00e0o b\u1ea3ng <code>DonHang<\/code>. C\u1ed9t n\u00e0y trong b\u1ea3ng <code>DonHang<\/code> ch\u00ednh l\u00e0 Kh\u00f3a ngo\u1ea1i, v\u00e0 n\u00f3 s\u1ebd tham chi\u1ebfu ng\u01b0\u1ee3c l\u1ea1i c\u1ed9t <code>MaKhachHang<\/code> (PK) trong b\u1ea3ng <code>KhachHang<\/code>.<\/span><\/p>\n<p><span>Nh\u1edd r\u00e0ng bu\u1ed9c Kh\u00f3a ngo\u1ea1i n\u00e0y, h\u1ec7 th\u1ed1ng s\u1ebd ng\u0103n b\u1ea1n t\u1ea1o ra m\u1ed9t \u0111\u01a1n h\u00e0ng c\u00f3 <code>MaKhachHang<\/code> kh\u00f4ng t\u1ed3n t\u1ea1i trong danh s\u00e1ch kh\u00e1ch h\u00e0ng. V\u00ed d\u1ee5, n\u1ebfu kh\u00f4ng c\u00f3 kh\u00e1ch h\u00e0ng n\u00e0o c\u00f3 <code>MaKhachHang<\/code> l\u00e0 123, b\u1ea1n kh\u00f4ng th\u1ec3 t\u1ea1o \u0111\u01a1n h\u00e0ng v\u1edbi gi\u00e1 tr\u1ecb Kh\u00f3a ngo\u1ea1i <code>MaKhachHang<\/code> l\u00e0 123.<\/span><\/p>\n<p><span>\u0110i\u1ec1u n\u00e0y gi\u00fap gi\u1eef cho database lu\u00f4n trong tr\u1ea1ng th\u00e1i &#8220;s\u1ea1ch&#8221;, \u0111\u1ea3m b\u1ea3o r\u1eb1ng m\u1ecdi \u0111\u01a1n h\u00e0ng \u0111\u1ec1u li\u00ean k\u1ebft \u0111\u1ebfn m\u1ed9t kh\u00e1ch h\u00e0ng th\u1ef1c s\u1ef1 t\u1ed3n t\u1ea1i trong h\u1ec7 th\u1ed1ng, tr\u00e1nh t\u00ecnh tr\u1ea1ng d\u1eef li\u1ec7u &#8220;m\u1ed3 c\u00f4i&#8221; hay kh\u00f4ng h\u1ee3p l\u1ec7.<\/span><\/p>\n<p><span><strong>V\u00ed d\u1ee5 2:<\/strong><\/span><\/p>\n<figure id=\"attachment_28932\" aria-describedby=\"caption-attachment-28932\" style=\"width: 1042px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/05\/Vi-du-ve-khoa-ngoai-1.webp\" alt=\"V\u00ed d\u1ee5 v\u1ec1 kh\u00f3a ngo\u1ea1i\" width=\"1042\" height=\"745\" class=\"size-full wp-image-28932\" title=\"\" srcset=\"https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/05\/Vi-du-ve-khoa-ngoai-1.webp 1042w, https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/05\/Vi-du-ve-khoa-ngoai-1-300x214.webp 300w, https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/05\/Vi-du-ve-khoa-ngoai-1-1024x732.webp 1024w, https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/05\/Vi-du-ve-khoa-ngoai-1-768x549.webp 768w, https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/05\/Vi-du-ve-khoa-ngoai-1-120x86.webp 120w, https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/05\/Vi-du-ve-khoa-ngoai-1-350x250.webp 350w, https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/05\/Vi-du-ve-khoa-ngoai-1-750x536.webp 750w\" sizes=\"auto, (max-width: 1042px) 100vw, 1042px\" \/><figcaption id=\"caption-attachment-28932\" class=\"wp-caption-text\">V\u00ed d\u1ee5 v\u1ec1 kh\u00f3a ngo\u1ea1i<\/figcaption><\/figure>\n<ul>\n<li><span><code>dept_id<\/code> l\u00e0 kh\u00f3a ch\u00ednh trong b\u1ea3ng department_info.<\/span><\/li>\n<li><span><code>dept_id<\/code> l\u00e0 kh\u00f3a ngo\u1ea1i trong b\u1ea3ng employee_info.<\/span><\/li>\n<\/ul>\n<p><span>\u0110i\u1ec1u n\u00e0y c\u00f3 ngh\u0129a l\u00e0 tr\u01b0\u1eddng <code>dept_id<\/code> c\u1ee7a b\u1ea3ng employee_info ch\u1ec9 c\u00f3 th\u1ec3 c\u00f3 nh\u1eefng gi\u00e1 tr\u1ecb c\u00f3 trong tr\u01b0\u1eddng <code>dept_id<\/code> c\u1ee7a b\u1ea3ng department_info.<\/span><\/p>\n<ul>\n<li><span>Tr\u01b0\u1eddng <code>dept_id<\/code> trong b\u1ea3ng department_info d\u00f9ng \u0111\u1ec3 nh\u1eadn d\u1ea1ng duy nh\u1ea5t c\u00e1c b\u1ea3n ghi trong b\u1ea3ng.<\/span><\/li>\n<li><span>Tr\u01b0\u1eddng <code>dept_id<\/code> trong b\u1ea3ng employee_info d\u00f9ng \u0111\u1ec3 bi\u1ebft nh\u00e2n vi\u00ean n\u00e0o \u0111ang l\u00e0m vi\u1ec7c \u1edf ph\u00f2ng ban n\u00e0o.<\/span><\/li>\n<\/ul>\n<h2><span class=\"ez-toc-section\" id=\"Loi-ich-cua-Foreign-Key-trong-DBMS\"><\/span><span>L\u1ee3i \u00edch c\u1ee7a Foreign Key trong DBMS<\/span><span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p><span>S\u1eed d\u1ee5ng Kh\u00f3a ngo\u1ea1i (Foreign Key &#8211; FK) mang l\u1ea1i nhi\u1ec1u l\u1ee3i \u00edch thi\u1ebft y\u1ebfu cho c\u01a1 s\u1edf d\u1eef li\u1ec7u quan h\u1ec7. Ch\u00fang kh\u00f4ng ch\u1ec9 gi\u00fap \u0111\u1ea3m b\u1ea3o t\u00ednh to\u00e0n v\u1eb9n v\u00e0 nh\u1ea5t qu\u00e1n d\u1eef li\u1ec7u, thi\u1ebft l\u1eadp m\u1ed1i quan h\u1ec7 r\u00f5 r\u00e0ng gi\u1eefa c\u00e1c b\u1ea3ng, m\u00e0 c\u00f2n t\u1ed1i \u01b0u h\u00f3a truy v\u1ea5n, h\u1ed7 tr\u1ee3 b\u1ea3o tr\u00ec v\u00e0 t\u0103ng c\u01b0\u1eddng \u0111\u00e1ng k\u1ec3 b\u1ea3o m\u1eadt d\u1eef li\u1ec7u c\u1ee7a b\u1ea1n.<\/span><\/p>\n<p><span>Vi\u1ec7c tri\u1ec3n khai Foreign Key l\u00e0 m\u1ed9t y\u00eau c\u1ea7u c\u01a1 b\u1ea3n v\u00e0 quan tr\u1ecdng trong thi\u1ebft k\u1ebf database hi\u1ec7u qu\u1ea3. C\u00e1c l\u1ee3i \u00edch n\u00e0y c\u1ed9ng h\u01b0\u1edfng v\u1edbi nhau, t\u1ea1o n\u00ean m\u1ed9t n\u1ec1n t\u1ea3ng d\u1eef li\u1ec7u \u0111\u00e1ng tin c\u1eady, d\u1ec5 qu\u1ea3n l\u00fd v\u00e0 c\u00f3 hi\u1ec7u su\u1ea5t ho\u1ea1t \u0111\u1ed9ng t\u1ed1t, l\u00e0 y\u1ebfu t\u1ed1 then ch\u1ed1t cho m\u1ecdi h\u1ec7 th\u1ed1ng s\u1eed d\u1ee5ng database.<\/span><\/p>\n<h3><span class=\"ez-toc-section\" id=\"Dam-bao-tinh-toan-ven-du-lieu\"><\/span><span>\u0110\u1ea3m b\u1ea3o t\u00ednh to\u00e0n v\u1eb9n d\u1eef li\u1ec7u<\/span><span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p><span>L\u1ee3i \u00edch h\u00e0ng \u0111\u1ea7u v\u00e0 c\u1ed1t l\u00f5i c\u1ee7a Kh\u00f3a ngo\u1ea1i l\u00e0 duy tr\u00ec &#8220;t\u00ednh to\u00e0n v\u1eb9n tham chi\u1ebfu&#8221; (referential integrity). N\u00f3 ng\u0103n ch\u1eb7n vi\u1ec7c t\u1ea1o ra c\u00e1c b\u1ea3n ghi &#8220;m\u1ed3 c\u00f4i&#8221;, t\u1ee9c l\u00e0 nh\u1eefng d\u00f2ng d\u1eef li\u1ec7u \u1edf b\u1ea3ng con l\u1ea1i tham chi\u1ebfu \u0111\u1ebfn m\u1ed9t gi\u00e1 tr\u1ecb Kh\u00f3a ch\u00ednh kh\u00f4ng h\u1ec1 t\u1ed3n t\u1ea1i \u1edf b\u1ea3ng cha t\u01b0\u01a1ng \u1ee9ng.<\/span><\/p>\n<p><span>Nh\u1edd r\u00e0ng bu\u1ed9c Kh\u00f3a ngo\u1ea1i, h\u1ec7 qu\u1ea3n tr\u1ecb c\u01a1 s\u1edf d\u1eef li\u1ec7u (DBMS) s\u1ebd <strong>t\u1ef1 \u0111\u1ed9ng th\u1ef1c hi\u1ec7n ki\u1ec3m tra khi b\u1ea1n thao t\u00e1c d\u1eef li\u1ec7u<\/strong> (th\u00eam, s\u1eeda, x\u00f3a). N\u1ebfu h\u00e0nh \u0111\u1ed9ng n\u00e0o c\u00f3 nguy c\u01a1 l\u00e0m m\u1ea5t \u0111i s\u1ef1 nh\u1ea5t qu\u00e1n ho\u1eb7c ph\u00e1 v\u1ee1 m\u1ed1i li\u00ean k\u1ebft gi\u1eefa c\u00e1c b\u1ea3ng, h\u1ec7 th\u1ed1ng s\u1ebd l\u1eadp t\u1ee9c ng\u0103n ch\u1eb7n \u0111i\u1ec1u \u0111\u00f3 x\u1ea3y ra.<\/span><\/p>\n<p><span>\u0110i\u1ec1u n\u00e0y \u0111\u1ea3m b\u1ea3o r\u1eb1ng d\u1eef li\u1ec7u lu\u00f4n \u1edf tr\u1ea1ng th\u00e1i ch\u00ednh x\u00e1c, nh\u1ea5t qu\u00e1n gi\u1eefa c\u00e1c b\u1ea3ng c\u00f3 quan h\u1ec7. N\u00f3 lo\u1ea1i b\u1ecf r\u1ee7i ro nh\u1eadp sai m\u00e3 tham chi\u1ebfu ho\u1eb7c v\u00f4 t\u00ecnh x\u00f3a \u0111i d\u1eef li\u1ec7u cha trong khi v\u1eabn c\u00f2n d\u1eef li\u1ec7u con ph\u1ee5 thu\u1ed9c v\u00e0o n\u00f3, n\u00e2ng cao \u0111\u1ed9 tin c\u1eady t\u1ed5ng th\u1ec3.<\/span><\/p>\n<figure id=\"attachment_28933\" aria-describedby=\"caption-attachment-28933\" style=\"width: 800px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/05\/Loi-ich-cua-Foreign-Key-trong-DBMS-1.jpg\" alt=\" L\u1ee3i \u00edch c\u1ee7a Foreign Key trong DBMS\" width=\"800\" height=\"500\" class=\"size-full wp-image-28933\" title=\"\" srcset=\"https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/05\/Loi-ich-cua-Foreign-Key-trong-DBMS-1.jpg 800w, https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/05\/Loi-ich-cua-Foreign-Key-trong-DBMS-1-300x188.jpg 300w, https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/05\/Loi-ich-cua-Foreign-Key-trong-DBMS-1-768x480.jpg 768w, https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/05\/Loi-ich-cua-Foreign-Key-trong-DBMS-1-750x469.jpg 750w\" sizes=\"auto, (max-width: 800px) 100vw, 800px\" \/><figcaption id=\"caption-attachment-28933\" class=\"wp-caption-text\">L\u1ee3i \u00edch c\u1ee7a Foreign Key trong DBMS<\/figcaption><\/figure>\n<h3><span class=\"ez-toc-section\" id=\"Thiet-lap-moi-quan-he-ro-rang\"><\/span><span>Thi\u1ebft l\u1eadp m\u1ed1i quan h\u1ec7 r\u00f5 r\u00e0ng<\/span><span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p><span>Kh\u00f3a ngo\u1ea1i l\u00e0 c\u01a1 ch\u1ebf ti\u00eau chu\u1ea9n \u0111\u1ec3 \u0111\u1ecbnh ngh\u0129a v\u00e0 <strong>th\u1ec3 hi\u1ec7n m\u1ed1i quan h\u1ec7 gi\u1eefa c\u00e1c b\u1ea3ng<\/strong> trong m\u00f4 h\u00ecnh c\u01a1 s\u1edf d\u1eef li\u1ec7u quan h\u1ec7. Ch\u00fang gi\u00fap l\u00e0m s\u00e1ng t\u1ecf c\u00e1ch c\u00e1c th\u1ef1c th\u1ec3 (\u0111\u01b0\u1ee3c l\u01b0u trong c\u00e1c b\u1ea3ng) li\u00ean k\u1ebft v\u1edbi nhau, t\u1ea1o ra m\u1ed9t <a href=\"https:\/\/interdata.vn\/blog\/cau-truc-du-lieu\/\">c\u1ea5u tr\u00fac d\u1eef li\u1ec7u<\/a> m\u1ea1ch l\u1ea1c v\u00e0 d\u1ec5 hi\u1ec3u cho m\u1ecdi ng\u01b0\u1eddi l\u00e0m vi\u1ec7c v\u1edbi n\u00f3.<\/span><\/p>\n<p><span>Vi\u1ec7c x\u00e1c \u0111\u1ecbnh v\u00e0 \u00e1p d\u1ee5ng \u0111\u00fang c\u00e1c Kh\u00f3a ngo\u1ea1i l\u00e0 n\u1ec1n t\u1ea3ng quan tr\u1ecdng trong <strong>qu\u00e1 tr\u00ecnh chu\u1ea9n h\u00f3a database<\/strong> (normalization). \u0110i\u1ec1u n\u00e0y kh\u00f4ng ch\u1ec9 gi\u00fap thi\u1ebft k\u1ebf database tu\u00e2n th\u1ee7 c\u00e1c nguy\u00ean t\u1eafc t\u1ed1t, m\u00e0 c\u00f2n ph\u00e2n chia d\u1eef li\u1ec7u m\u1ed9t c\u00e1ch h\u1ee3p l\u00fd, tr\u00e1nh d\u01b0 th\u1eeba v\u00e0 \u0111\u1ea3m b\u1ea3o t\u00ednh logic c\u1ee7a to\u00e0n b\u1ed9 c\u1ea5u tr\u00fac.<\/span><\/p>\n<p><span>M\u1ed9t s\u01a1 \u0111\u1ed3 database c\u00f3 \u0111\u1ecbnh ngh\u0129a Kh\u00f3a ngo\u1ea1i r\u00f5 r\u00e0ng gi\u00fap c\u00e1c nh\u00e0 ph\u00e1t tri\u1ec3n, qu\u1ea3n tr\u1ecb vi\u00ean, hay b\u1ea5t k\u1ef3 ai m\u1edbi ti\u1ebfp c\u1eadn \u0111\u1ec1u nhanh ch\u00f3ng n\u1eafm b\u1eaft \u0111\u01b0\u1ee3c b\u1ee9c tranh t\u1ed5ng th\u1ec3 v\u1ec1 c\u00e1ch d\u1eef li\u1ec7u \u0111\u01b0\u1ee3c t\u1ed5 ch\u1ee9c v\u00e0 k\u1ebft n\u1ed1i trong h\u1ec7 th\u1ed1ng.<\/span><\/p>\n<h3><span class=\"ez-toc-section\" id=\"Toi-uu-hoa-truy-van\"><\/span><span>T\u1ed1i \u01b0u h\u00f3a truy v\u1ea5n<\/span><span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p><span>Khi c\u00e1c b\u1ea3ng trong database \u0111\u01b0\u1ee3c li\u00ean k\u1ebft th\u00f4ng qua Kh\u00f3a ngo\u1ea1i, h\u1ec7 qu\u1ea3n tr\u1ecb c\u01a1 s\u1edf d\u1eef li\u1ec7u (DBMS) s\u1ebd hi\u1ec3u r\u00f5 m\u1ed1i quan h\u1ec7 ng\u1eef ngh\u0129a gi\u1eefa ch\u00fang. Th\u00f4ng tin n\u00e0y c\u1ef1c k\u1ef3 h\u1eefu \u00edch cho tr\u00ecnh t\u1ed1i \u01b0u h\u00f3a truy v\u1ea5n c\u1ee7a DBMS \u0111\u1ec3 t\u00ecm ra c\u00e1ch th\u1ee9c truy xu\u1ea5t d\u1eef li\u1ec7u hi\u1ec7u qu\u1ea3 nh\u1ea5t.<\/span><\/p>\n<p><span>Vi\u1ec7c hi\u1ec3u r\u00f5 m\u1ed1i quan h\u1ec7 n\u00e0y cho ph\u00e9p DBMS s\u1eed d\u1ee5ng c\u00e1c k\u1ebf ho\u1ea1ch th\u1ef1c thi truy v\u1ea5n t\u1ed1i \u01b0u h\u01a1n, \u0111\u1eb7c bi\u1ec7t khi b\u1ea1n c\u1ea7n k\u1ebft h\u1ee3p d\u1eef li\u1ec7u t\u1eeb nhi\u1ec1u b\u1ea3ng li\u00ean quan b\u1eb1ng c\u00e1c c\u00e2u l\u1ec7nh JOIN trong <a href=\"https:\/\/interdata.vn\/blog\/structured-query-language-sql-la-gi\/\">SQL<\/a>. \u0110i\u1ec1u n\u00e0y gi\u00fap truy xu\u1ea5t d\u1eef li\u1ec7u nhanh ch\u00f3ng v\u00e0 hi\u1ec7u qu\u1ea3 h\u01a1n so v\u1edbi vi\u1ec7c kh\u00f4ng c\u00f3 Kh\u00f3a ngo\u1ea1i.<\/span><\/p>\n<p><span>K\u1ebft qu\u1ea3 l\u00e0 c\u00e1c \u1ee9ng d\u1ee5ng ho\u1ea1t \u0111\u1ed9ng nhanh h\u01a1n, th\u1eddi gian ph\u1ea3n h\u1ed3i khi l\u1ea5y d\u1eef li\u1ec7u gi\u1ea3m xu\u1ed1ng. Kh\u00f3a ngo\u1ea1i cung c\u1ea5p manh m\u1ed1i quan tr\u1ecdng \u0111\u1ec3 DBMS c\u00f3 th\u1ec3 \u0111i th\u1eb3ng v\u00e0o c\u00e1c d\u1eef li\u1ec7u li\u00ean quan thay v\u00ec ph\u1ea3i x\u1eed l\u00fd to\u00e0n b\u1ed9 d\u1eef li\u1ec7u m\u1ed9t c\u00e1ch &#8220;m\u00f9 qu\u00e1ng&#8221;, c\u1ea3i thi\u1ec7n hi\u1ec7u su\u1ea5t \u0111\u00e1ng k\u1ec3.<\/span><\/p>\n<h3><span class=\"ez-toc-section\" id=\"Ho-tro-bao-tri-co-so-du-lieu\"><\/span><span>H\u1ed7 tr\u1ee3 b\u1ea3o tr\u00ec c\u01a1 s\u1edf d\u1eef li\u1ec7u<\/span><span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p><span>Kh\u00f3a ngo\u1ea1i \u0111\u00f3ng vai tr\u00f2 thi\u1ebft y\u1ebfu trong c\u00e1c t\u00e1c v\u1ee5 <strong>b\u1ea3o tr\u00ec database \u0111\u1ecbnh k\u1ef3 v\u00e0 kh\u1ea9n c\u1ea5p<\/strong>. Ch\u00fang gi\u00fap \u0111\u1ea3m b\u1ea3o r\u1eb1ng khi th\u1ef1c hi\u1ec7n c\u00e1c quy tr\u00ecnh nh\u01b0 sao l\u01b0u, ph\u1ee5c h\u1ed3i d\u1eef li\u1ec7u, chuy\u1ec3n \u0111\u1ed5i l\u01b0\u1ee3c \u0111\u1ed3 (<a href=\"https:\/\/interdata.vn\/blog\/schema-la-gi\/\">schema<\/a> migration) hay nh\u1eadp\/xu\u1ea5t d\u1eef li\u1ec7u, t\u00ednh to\u00e0n v\u1eb9n v\u00e0 s\u1ef1 nh\u1ea5t qu\u00e1n gi\u1eefa c\u00e1c b\u1ea3ng lu\u00f4n \u0111\u01b0\u1ee3c duy tr\u00ec.<\/span><\/p>\n<p><span>R\u00e0ng bu\u1ed9c Kh\u00f3a ngo\u1ea1i cung c\u1ea5p m\u1ed9t l\u1edbp b\u1ea3o v\u1ec7 t\u1ef1 \u0111\u1ed9ng trong su\u1ed1t qu\u00e1 tr\u00ecnh b\u1ea3o tr\u00ec. B\u1ea5t k\u1ef3 thay \u0111\u1ed5i n\u00e0o c\u00f3 nguy c\u01a1 ph\u00e1 v\u1ee1 m\u1ed1i quan h\u1ec7 \u0111\u00e3 \u0111\u01b0\u1ee3c \u0111\u1ecbnh ngh\u0129a s\u1ebd b\u1ecb h\u1ec7 th\u1ed1ng c\u1ea3nh b\u00e1o ho\u1eb7c ng\u0103n ch\u1eb7n. \u0110i\u1ec1u n\u00e0y gi\u00fap gi\u1ea3m thi\u1ec3u r\u1ee7i ro ph\u00e1t sinh l\u1ed7i d\u1eef li\u1ec7u sau khi ho\u00e0n th\u00e0nh c\u00f4ng vi\u1ec7c b\u1ea3o tr\u00ec.<\/span><\/p>\n<p><span>S\u1ef1 c\u00f3 m\u1eb7t c\u1ee7a Kh\u00f3a ngo\u1ea1i gi\u00fap \u0111\u01a1n gi\u1ea3n h\u00f3a v\u00e0 an to\u00e0n h\u00f3a c\u00e1c quy tr\u00ecnh b\u1ea3o tr\u00ec ph\u1ee9c t\u1ea1p. Thay v\u00ec ph\u1ea3i vi\u1ebft c\u00e1c script ki\u1ec3m tra t\u00ednh nh\u1ea5t qu\u00e1n th\u1ee7 c\u00f4ng (r\u1ea5t d\u1ec5 sai s\u00f3t), b\u1ea1n c\u00f3 th\u1ec3 d\u1ef1a v\u00e0o ch\u00ednh c\u01a1 ch\u1ebf c\u1ee7a DBMS \u0111\u1ec3 \u0111\u1ea3m b\u1ea3o database lu\u00f4n trong tr\u1ea1ng th\u00e1i ho\u1ea1t \u0111\u1ed9ng \u0111\u00fang sau b\u1ea3o tr\u00ec.<\/span><\/p>\n<h3><span class=\"ez-toc-section\" id=\"Tang-cuong-bao-mat-du-lieu\"><\/span><span>T\u0103ng c\u01b0\u1eddng b\u1ea3o m\u1eadt d\u1eef li\u1ec7u<\/span><span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p><span>M\u1eb7c d\u00f9 kh\u00f4ng ph\u1ea3i l\u00e0 c\u01a1 ch\u1ebf ki\u1ec3m so\u00e1t quy\u1ec1n truy c\u1eadp tr\u1ef1c ti\u1ebfp, Kh\u00f3a ngo\u1ea1i <strong>g\u00f3p ph\u1ea7n t\u0103ng c\u01b0\u1eddng b\u1ea3o m\u1eadt d\u1eef li\u1ec7u theo c\u00e1ch quan tr\u1ecdng<\/strong>. Ch\u00fang ng\u0103n ch\u1eb7n c\u00e1c h\u00e0nh \u0111\u1ed9ng s\u1eeda \u0111\u1ed5i ho\u1eb7c x\u00f3a d\u1eef li\u1ec7u quan tr\u1ecdng trong b\u1ea3ng cha n\u1ebfu vi\u1ec7c \u0111\u00f3 l\u00e0m m\u1ea5t \u0111i m\u1ed1i li\u00ean k\u1ebft v\u1edbi d\u1eef li\u1ec7u \u0111ang \u0111\u01b0\u1ee3c tham chi\u1ebfu b\u1edfi Kh\u00f3a ngo\u1ea1i \u1edf b\u1ea3ng con.<\/span><\/p>\n<p><span>\u0110i\u1ec1u n\u00e0y c\u00f3 ngh\u0129a l\u00e0, Kh\u00f3a ngo\u1ea1i b\u1ea3o v\u1ec7 t\u00ednh to\u00e0n v\u1eb9n c\u1ee7a c\u00e1c m\u1ed1i quan h\u1ec7, qua \u0111\u00f3 gi\u00e1n ti\u1ebfp b\u1ea3o v\u1ec7 t\u00ednh h\u1ee3p l\u1ec7 c\u1ee7a to\u00e0n b\u1ed9 c\u1ea5u tr\u00fac d\u1eef li\u1ec7u. N\u00f3 ng\u0103n ch\u1eb7n c\u00e1c h\u00e0nh \u0111\u1ed9ng \u0111\u1ed9c h\u1ea1i ho\u1eb7c v\u00f4 \u00fd c\u00f3 th\u1ec3 b\u1ecb l\u1ea1m d\u1ee5ng \u0111\u1ec3 l\u00e0m h\u1ecfng ho\u1eb7c l\u00e0m sai l\u1ec7ch m\u1ed1i li\u00ean k\u1ebft d\u1eef li\u1ec7u quan tr\u1ecdng trong database.<\/span><\/p>\n<p><span>B\u1eb1ng c\u00e1ch \u0111\u1ea3m b\u1ea3o r\u1eb1ng d\u1eef li\u1ec7u lu\u00f4n \u0111\u01b0\u1ee3c k\u1ebft n\u1ed1i \u0111\u00fang c\u00e1ch, Kh\u00f3a ngo\u1ea1i gi\u00fap ng\u0103n ch\u1eb7n c\u00e1c <a href=\"https:\/\/interdata.vn\/blog\/lo-hong-bao-mat-la-gi\/\">l\u1ed7 h\u1ed5ng b\u1ea3o m\u1eadt<\/a> c\u00f3 th\u1ec3 ph\u00e1t sinh t\u1eeb d\u1eef li\u1ec7u kh\u00f4ng nh\u1ea5t qu\u00e1n. Ch\u00fang b\u1ed5 sung m\u1ed9t l\u1edbp b\u1ea3o v\u1ec7 logic, \u0111\u1ea3m b\u1ea3o ch\u1ec9 nh\u1eefng thao t\u00e1c h\u1ee3p l\u1ec7 theo c\u1ea5u tr\u00fac quan h\u1ec7 m\u1edbi \u0111\u01b0\u1ee3c th\u1ef1c hi\u1ec7n tr\u00ean database.<\/span><\/p>\n<h2><span class=\"ez-toc-section\" id=\"Cu-phap-tao-xoa-Foreign-Key-trong-DBMS\"><\/span><span>C\u00fa ph\u00e1p t\u1ea1o, x\u00f3a Foreign Key trong DBMS<\/span><span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p><span>C\u00fa ph\u00e1p \u0111\u1ec3 t\u1ea1o kh\u00f3a ngo\u1ea1i trong DBMS nh\u01b0 sau:<\/span><\/p>\n<p><span><strong>C\u00fa ph\u00e1p t\u1ea1o kh\u00f3a ngo\u1ea1i b\u1eb1ng l\u1ec7nh CREATE TABLE: <\/strong><\/span><\/p>\n<pre><span>CREATE TABLE bang_con\r\n(\r\ncot1 kieudulieu [ NULL | NOT NULL ],\r\ncot2 kieudulieu [ NULL | NOT NULL ],\r\n\u2026\r\n\r\nCONSTRAINT fk_ten\r\nFOREIGN KEY (cot_con1, cot_con2, \u2026 cot_con_n)\r\nREFERENCES bang_me (cot_me1, cot_me2, \u2026 cot_me_n)\r\n[ ON DELETE { NO ACTION | CASCADE | SET NULL | SET DEFAULT } ]\r\n[ ON UPDATE { NO ACTION | CASCADE | SET NULL | SET DEFAULT } ]\r\n);<\/span><\/pre>\n<ul>\n<li><span><strong>bang_con<\/strong>: L\u00e0 t\u00ean c\u1ee7a b\u1ea3ng con b\u1ea1n mu\u1ed1n t\u1ea1o.<br \/>\n<\/span><\/li>\n<li><span><strong>cot1,cot2<\/strong>: L\u00e0 c\u00e1c c\u1ed9t s\u1ebd \u0111\u01b0\u1ee3c khai b\u00e1o trong b\u1ea3ng con. M\u1ed7i c\u1ed9t c\u1ea7n ch\u1ec9 \u0111\u1ecbnh r\u00f5 <a href=\"https:\/\/interdata.vn\/blog\/kieu-du-lieu-data-type\/\">ki\u1ec3u d\u1eef li\u1ec7u<\/a> v\u00e0 tr\u1ea1ng th\u00e1i NULL\/NOT NULL. N\u1ebfu kh\u00f4ng khai b\u00e1o, m\u1eb7c \u0111\u1ecbnh c\u1ed9t s\u1ebd \u0111\u01b0\u1ee3c cho ph\u00e9p NULL.<br \/>\n<\/span><\/li>\n<li><span><strong>fk_ten<\/strong>: L\u00e0 t\u00ean c\u1ee7a r\u00e0ng bu\u1ed9c kh\u00f3a ngo\u1ea1i b\u1ea1n s\u1ebd t\u1ea1o.<br \/>\n<\/span><\/li>\n<li><span><strong>cot_con1, cot_con2, \u2026 cot_con_n<\/strong>: L\u00e0 c\u00e1c c\u1ed9t trong b\u1ea3ng con (bang_con) \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng \u0111\u1ec3 tham chi\u1ebfu t\u1edbi c\u00e1c c\u1ed9t kh\u00f3a ch\u00ednh trong b\u1ea3ng m\u1eb9 (bang_me).<br \/>\n<\/span><\/li>\n<li><span><strong>bang_me<\/strong>: L\u00e0 b\u1ea3ng m\u1eb9 ch\u1ee9a kh\u00f3a ch\u00ednh \u0111\u01b0\u1ee3c d\u00f9ng \u0111\u1ec3 thi\u1ebft l\u1eadp quan h\u1ec7 v\u1edbi b\u1ea3ng con.<br \/>\n<\/span><\/li>\n<li><span> <strong>cot_me_n<\/strong>: L\u00e0 c\u00e1c c\u1ed9t t\u1ea1o n\u00ean kh\u00f3a ch\u00ednh trong b\u1ea3ng m\u1eb9. Vi\u1ec7c t\u1ea1o kh\u00f3a ngo\u1ea1i s\u1ebd r\u00e0ng bu\u1ed9c c\u00e1c c\u1ed9t c\u1ee7a b\u1ea3ng con v\u1edbi c\u00e1c c\u1ed9t n\u00e0y trong b\u1ea3ng m\u1eb9.<br \/>\n<\/span><\/li>\n<li><span><strong>ON DELETE<\/strong>: T\u00f9y ch\u1ecdn n\u00e0y ch\u1ec9 \u0111\u1ecbnh h\u00e0nh vi \u00e1p d\u1ee5ng cho d\u1eef li\u1ec7u con khi d\u1eef li\u1ec7u m\u1eb9 b\u1ecb x\u00f3a. C\u00e1c t\u00f9y ch\u1ecdn bao g\u1ed3m: NO ACTION, CASCADE, SET NULL, v\u00e0 SET DEFAULT.<br \/>\n<\/span><\/li>\n<li><span><strong>ON<\/strong> <strong>UPDATE<\/strong>: T\u00f9y ch\u1ecdn x\u00e1c \u0111\u1ecbnh h\u00e0nh vi \u00e1p d\u1ee5ng cho d\u1eef li\u1ec7u con khi d\u1eef li\u1ec7u m\u1eb9 \u0111\u01b0\u1ee3c c\u1eadp nh\u1eadt. C\u00e1c l\u1ef1a ch\u1ecdn t\u01b0\u01a1ng t\u1ef1 nh\u01b0 ON DELETE: NO ACTION, CASCADE, SET NULL, SET DEFAULT.<br \/>\n<\/span><\/li>\n<li><span><strong>NO ACTION<\/strong>: Khi s\u1eed d\u1ee5ng v\u1edbi ON DELETE ho\u1eb7c ON UPDATE, t\u00f9y ch\u1ecdn n\u00e0y c\u00f3 ngh\u0129a l\u00e0 kh\u00f4ng th\u1ef1c hi\u1ec7n b\u1ea5t k\u1ef3 thay \u0111\u1ed5i n\u00e0o v\u1edbi d\u1eef li\u1ec7u con n\u1ebfu d\u1eef li\u1ec7u m\u1eb9 b\u1ecb x\u00f3a ho\u1eb7c c\u1eadp nh\u1eadt.<br \/>\n<\/span><\/li>\n<li><span><strong>CASCADE<\/strong>: D\u00f9ng trong ON DELETE ho\u1eb7c ON UPDATE, ngh\u0129a l\u00e0 d\u1eef li\u1ec7u con s\u1ebd b\u1ecb x\u00f3a ho\u1eb7c c\u1eadp nh\u1eadt theo khi d\u1eef li\u1ec7u m\u1eb9 thay \u0111\u1ed5i.<br \/>\n<\/span><\/li>\n<li><span><strong>SET NULL<\/strong>: Khi d\u1eef li\u1ec7u m\u1eb9 b\u1ecb x\u00f3a ho\u1eb7c c\u1eadp nh\u1eadt, d\u1eef li\u1ec7u con s\u1ebd \u0111\u01b0\u1ee3c \u0111\u1eb7t th\u00e0nh NULL n\u1ebfu ch\u1ecdn t\u00f9y ch\u1ecdn n\u00e0y.<br \/>\n<\/span><\/li>\n<li><span><strong>SET DEFAULT<\/strong>: Ngh\u0129a l\u00e0 khi c\u00f3 s\u1ef1 thay \u0111\u1ed5i \u1edf d\u1eef li\u1ec7u m\u1eb9, d\u1eef li\u1ec7u con s\u1ebd \u0111\u01b0\u1ee3c g\u00e1n v\u1ec1 gi\u00e1 tr\u1ecb m\u1eb7c \u0111\u1ecbnh \u0111\u00e3 thi\u1ebft l\u1eadp tr\u01b0\u1edbc \u0111\u00f3.<\/span><\/li>\n<\/ul>\n<figure id=\"attachment_28934\" aria-describedby=\"caption-attachment-28934\" style=\"width: 800px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/05\/Cu-phap-tao-xoa-khoa-ngoai-trong-DBMS-1.jpg\" alt=\" C\u00fa ph\u00e1p t\u1ea1o, x\u00f3a kh\u00f3a ngo\u1ea1i trong DBMS\" width=\"800\" height=\"500\" class=\"size-full wp-image-28934\" title=\"\" srcset=\"https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/05\/Cu-phap-tao-xoa-khoa-ngoai-trong-DBMS-1.jpg 800w, https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/05\/Cu-phap-tao-xoa-khoa-ngoai-trong-DBMS-1-300x188.jpg 300w, https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/05\/Cu-phap-tao-xoa-khoa-ngoai-trong-DBMS-1-768x480.jpg 768w, https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/05\/Cu-phap-tao-xoa-khoa-ngoai-trong-DBMS-1-750x469.jpg 750w\" sizes=\"auto, (max-width: 800px) 100vw, 800px\" \/><figcaption id=\"caption-attachment-28934\" class=\"wp-caption-text\">C\u00fa ph\u00e1p t\u1ea1o, x\u00f3a kh\u00f3a ngo\u1ea1i trong DBMS<\/figcaption><\/figure>\n<p><span><strong>C\u00fa ph\u00e1p t\u1ea1o kh\u00f3a ngo\u1ea1i b\u1eb1ng l\u1ec7nh ALTER TABLE<\/strong><\/span><\/p>\n<pre><span> ALTER TABLE bang_con\r\nADD CONSTRAINT fk_ten\r\nFOREIGN KEY (cot_con1, cot_con2, \u2026 cot_con_n)\r\nREFERENCES bang_me (cot_me1, cot_me2, \u2026 cot_me_n);<\/span><\/pre>\n<ul>\n<li><span><strong>bang_con<\/strong>: \u0110\u00e2y l\u00e0 t\u00ean c\u1ee7a b\u1ea3ng con m\u00e0 b\u1ea1n mu\u1ed1n t\u1ea1o trong c\u01a1 s\u1edf d\u1eef li\u1ec7u.<br \/>\n<\/span><\/li>\n<li><span><strong>fk_ten<\/strong>: L\u00e0 t\u00ean c\u1ee7a r\u00e0ng bu\u1ed9c kh\u00f3a ngo\u1ea1i m\u00e0 b\u1ea1n s\u1ebd thi\u1ebft l\u1eadp.<br \/>\n<\/span><\/li>\n<li><span><strong>cot_con1, cot_con2, \u2026 cot_con_n<\/strong>: C\u00e1c c\u1ed9t trong b\u1ea3ng con (bang_con) \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng \u0111\u1ec3 tham chi\u1ebfu t\u1edbi kh\u00f3a ch\u00ednh trong b\u1ea3ng m\u1eb9 (bang_me).<br \/>\n<\/span><\/li>\n<li><span><strong>bang_me<\/strong>: T\u00ean c\u1ee7a b\u1ea3ng m\u1eb9 \u2013 n\u01a1i ch\u1ee9a kh\u00f3a ch\u00ednh \u0111\u01b0\u1ee3c tham chi\u1ebfu b\u1edfi b\u1ea3ng con.<br \/>\n<\/span><\/li>\n<li><span><strong>cot_me1, cot_me2, \u2026 cot_me_n<\/strong>: C\u00e1c c\u1ed9t trong b\u1ea3ng m\u1eb9 t\u1ea1o th\u00e0nh kh\u00f3a ch\u00ednh. Kh\u00f3a ngo\u1ea1i s\u1ebd t\u1ea1o m\u1ed1i r\u00e0ng bu\u1ed9c gi\u1eefa c\u00e1c c\u1ed9t n\u00e0y v\u00e0 c\u00e1c c\u1ed9t t\u01b0\u01a1ng \u1ee9ng trong b\u1ea3ng con.<\/span><\/li>\n<\/ul>\n<p><span><strong>C\u00fa ph\u00e1p \u0111\u1ec3 x\u00f3a kh\u00f3a ngo\u1ea1i:<\/strong><\/span><\/p>\n<pre><span>ALTER TABLE Child_table_name\r\nDROP FOREIGN KEY Child_foreign_key_name;<\/span><\/pre>\n<h2><span class=\"ez-toc-section\" id=\"Cau-hoi-thuong-gap-ve-Foreign-Key\"><\/span><span>C\u00e2u h\u1ecfi th\u01b0\u1eddng g\u1eb7p v\u1ec1 Foreign Key<\/span><span class=\"ez-toc-section-end\"><\/span><\/h2>\n<h3><span class=\"ez-toc-section\" id=\"Foreign-Key-dung-de-lam-gi-trong-co-so-du-lieu\"><\/span><span>Foreign Key d\u00f9ng \u0111\u1ec3 l\u00e0m g\u00ec trong c\u01a1 s\u1edf d\u1eef li\u1ec7u?<\/span><span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p><span>Foreign Key d\u00f9ng \u0111\u1ec3 thi\u1ebft l\u1eadp m\u1ed1i quan h\u1ec7 gi\u1eefa c\u00e1c b\u1ea3ng trong database quan h\u1ec7. N\u00f3 \u0111\u1ea3m b\u1ea3o r\u1eb1ng d\u1eef li\u1ec7u \u1edf m\u1ed9t b\u1ea3ng (b\u1ea3ng con) tham chi\u1ebfu \u0111\u1ebfn d\u1eef li\u1ec7u h\u1ee3p l\u1ec7, \u0111ang t\u1ed3n t\u1ea1i \u1edf b\u1ea3ng kh\u00e1c (b\u1ea3ng cha), duy tr\u00ec t\u00ednh to\u00e0n v\u1eb9n tham chi\u1ebfu c\u1ee7a d\u1eef li\u1ec7u.<\/span><\/p>\n<h3><span class=\"ez-toc-section\" id=\"Mot-bang-trong-database-co-the-co-nhieu-hon-mot-Khoa-ngoai-duoc-khong\"><\/span><span>M\u1ed9t b\u1ea3ng trong database c\u00f3 th\u1ec3 c\u00f3 nhi\u1ec1u h\u01a1n m\u1ed9t Kh\u00f3a ngo\u1ea1i \u0111\u01b0\u1ee3c kh\u00f4ng?<\/span><span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p><span>\u0110\u01b0\u1ee3c, m\u1ed9t b\u1ea3ng ho\u00e0n to\u00e0n c\u00f3 th\u1ec3 c\u00f3 nhi\u1ec1u Kh\u00f3a ngo\u1ea1i. M\u1ed7i Kh\u00f3a ngo\u1ea1i c\u00f3 th\u1ec3 tham chi\u1ebfu \u0111\u1ebfn Kh\u00f3a ch\u00ednh c\u1ee7a m\u1ed9t b\u1ea3ng kh\u00e1c nhau ho\u1eb7c th\u1eadm ch\u00ed tham chi\u1ebfu nhi\u1ec1u l\u1ea7n \u0111\u1ebfn Kh\u00f3a ch\u00ednh c\u1ee7a c\u00f9ng m\u1ed9t b\u1ea3ng (d\u00f9 tr\u01b0\u1eddng h\u1ee3p sau \u00edt ph\u1ed5 bi\u1ebfn h\u01a1n).<\/span><\/p>\n<h3><span class=\"ez-toc-section\" id=\"Khoa-ngoai-co-bat-buoc-phai-chua-gia-tri-NOT-NULL-khong\"><\/span><span>Kh\u00f3a ngo\u1ea1i c\u00f3 b\u1eaft bu\u1ed9c ph\u1ea3i ch\u1ee9a gi\u00e1 tr\u1ecb (NOT NULL) kh\u00f4ng?<\/span><span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p><span>Kh\u00f4ng b\u1eaft bu\u1ed9c. M\u1eb7c \u0111\u1ecbnh, m\u1ed9t c\u1ed9t Kh\u00f3a ngo\u1ea1i c\u00f3 th\u1ec3 ch\u1ee9a gi\u00e1 tr\u1ecb NULL, tr\u1eeb khi c\u1ed9t \u0111\u00f3 \u0111\u01b0\u1ee3c \u0111\u1ecbnh ngh\u0129a r\u00f5 r\u00e0ng v\u1edbi r\u00e0ng bu\u1ed9c NOT NULL ho\u1eb7c l\u00e0 m\u1ed9t ph\u1ea7n c\u1ee7a Kh\u00f3a ch\u00ednh\/Kh\u00f3a \u1ee9ng vi\u00ean trong b\u1ea3ng con \u0111\u00f3.<\/span><\/p>\n<h3><span class=\"ez-toc-section\" id=\"Khi-thiet-ke-database-khi-nao-nen-su-dung-Khoa-ngoai\"><\/span><span>Khi thi\u1ebft k\u1ebf database, khi n\u00e0o n\u00ean s\u1eed d\u1ee5ng Kh\u00f3a ngo\u1ea1i?<\/span><span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p><span>B\u1ea1n n\u00ean s\u1eed d\u1ee5ng Kh\u00f3a ngo\u1ea1i b\u1ea5t c\u1ee9 khi n\u00e0o c\u00f3 m\u1ed1i quan h\u1ec7 gi\u1eefa hai b\u1ea3ng v\u00e0 b\u1ea1n mu\u1ed1n \u0111\u1ea3m b\u1ea3o r\u1eb1ng d\u1eef li\u1ec7u tham chi\u1ebfu (\u1edf b\u1ea3ng con) lu\u00f4n t\u01b0\u01a1ng \u1ee9ng v\u1edbi d\u1eef li\u1ec7u g\u1ed1c \u0111ang t\u1ed3n t\u1ea1i (\u1edf b\u1ea3ng cha), t\u1ee9c l\u00e0 c\u1ea7n \u0111\u1ea3m b\u1ea3o t\u00ednh to\u00e0n v\u1eb9n tham chi\u1ebfu.<\/span><\/p>\n<p>Qua b\u00e0i vi\u1ebft, b\u1ea1n \u0111\u00e3 n\u1eafm \u0111\u01b0\u1ee3c kh\u00e1i ni\u1ec7m Foreign Key l\u00e0 g\u00ec, c\u00e1ch s\u1eed d\u1ee5ng, c\u0169ng nh\u01b0 vai tr\u00f2 kh\u00f4ng th\u1ec3 thi\u1ebfu c\u1ee7a kh\u00f3a ngo\u1ea1i trong vi\u1ec7c x\u00e2y d\u1ef1ng c\u01a1 s\u1edf d\u1eef li\u1ec7u hi\u1ec7u qu\u1ea3 v\u00e0 an to\u00e0n. Vi\u1ec7c \u00e1p d\u1ee5ng \u0111\u00fang Foreign Key gi\u00fap b\u1ea1n t\u1ea1o ra h\u1ec7 th\u1ed1ng d\u1eef li\u1ec7u ch\u1eb7t ch\u1ebd, d\u1ec5 b\u1ea3o tr\u00ec v\u00e0 \u00edt l\u1ed7i h\u01a1n.<\/p>\n<p>\u0110\u1ec3 tri\u1ec3n khai h\u1ec7 th\u1ed1ng c\u01a1 s\u1edf d\u1eef li\u1ec7u th\u1ef1c t\u1ebf, c\u1ea7n m\u00f4i tr\u01b0\u1eddng <a href=\"https:\/\/interdata.vn\/blog\/may-chu-server-la-gi\/\">m\u00e1y ch\u1ee7<\/a> \u0111\u1ec3 thi\u1ebft l\u1eadp, qu\u1ea3n tr\u1ecb v\u00e0 ki\u1ec3m th\u1eed c\u01a1 s\u1edf d\u1eef li\u1ec7u (DBMS) nh\u01b0 <a href=\"https:\/\/interdata.vn\/blog\/mysql-la-gi\/\">MySQL<\/a>, <a href=\"https:\/\/interdata.vn\/blog\/postgresql-la-gi\/\">PostgreSQL<\/a>, SQL Server\u2026 D\u1ecbch v\u1ee5 <a href=\"https:\/\/interdata.vn\/thue-vps\/\">thu\u00ea VPS<\/a> l\u00e0 gi\u1ea3i ph\u00e1p ph\u00f9 h\u1ee3p. N\u1ebfu b\u1ea1n \u0111ang t\u00ecm m\u00f4i tr\u01b0\u1eddng \u0111\u1ec3 th\u1ef1c h\u00e0nh ho\u1eb7c tri\u1ec3n khai h\u1ec7 qu\u1ea3n tr\u1ecb c\u01a1 s\u1edf d\u1eef li\u1ec7u (DBMS) c\u00f3 s\u1eed d\u1ee5ng kh\u00f3a ngo\u1ea1i, d\u1ecbch v\u1ee5 <a href=\"https:\/\/interdata.vn\/vps-linux\">VPS Linux<\/a> v\u1edbi Full <a href=\"https:\/\/interdata.vn\/blog\/root-access-la-gi\/\">Root Access<\/a>, h\u1ed7 tr\u1ee3 c\u00e0i \u0111\u1eb7t <a href=\"https:\/\/interdata.vn\/blog\/he-dieu-hanh\/\">h\u1ec7 \u0111i\u1ec1u h\u00e0nh<\/a> nh\u01b0 <a href=\"https:\/\/interdata.vn\/blog\/ubuntu-server-la-gi\/\">Ubuntu<\/a>, <a href=\"https:\/\/interdata.vn\/blog\/he-dieu-hanh-centos\/\">CentOS<\/a>, Debian&#8230;, b\u1ea1n d\u1ec5 d\u00e0ng t\u00f9y ch\u1ec9nh c\u1ea5u h\u00ecnh, t\u1ea1o b\u1ea3ng, thi\u1ebft l\u1eadp kh\u00f3a ngo\u1ea1i v\u00e0 ki\u1ec3m th\u1eed to\u00e0n b\u1ed9 h\u1ec7 th\u1ed1ng m\u1ed9t c\u00e1ch ch\u1ee7 \u0111\u1ed9ng.<\/p>\n<p>T\u1ea1i InterData, d\u1ecbch v\u1ee5 <a href=\"https:\/\/interdata.vn\/blog\/vps-la-gi\/\">VPS<\/a> <a href=\"https:\/\/interdata.vn\/blog\/he-dieu-hanh-linux-la-gi\/\">Linux<\/a> s\u1eed d\u1ee5ng <strong><a href=\"https:\/\/interdata.vn\/blog\/o-cung-ssd-nvme-la-gi\/\">\u1ed5 c\u1ee9ng SSD NVMe<\/a> U.2 t\u1ed1c \u0111\u1ed9 cao<\/strong>, <a href=\"https:\/\/interdata.vn\/blog\/bang-thong-la-gi\/\">b\u0103ng th\u00f4ng<\/a> r\u1ed9ng v\u00e0 <strong><a href=\"https:\/\/interdata.vn\/blog\/uptime-la-gi\/\">uptime<\/a> \u0111\u1ea1t 99.9%<\/strong>, gi\u00fap h\u1ec7 th\u1ed1ng lu\u00f4n \u1ed5n \u0111\u1ecbnh trong su\u1ed1t qu\u00e1 tr\u00ecnh v\u1eadn h\u00e0nh. <strong>Ch\u1ec9 t\u1eeb 95K\/th\u00e1ng<\/strong>, b\u1ea1n \u0111\u00e3 c\u00f3 th\u1ec3 kh\u1edfi t\u1ea1o nhanh <a href=\"https:\/\/interdata.vn\/blog\/dedicated-server-la-gi\/\">m\u00e1y ch\u1ee7 ri\u00eang<\/a> v\u1edbi hi\u1ec7u su\u1ea5t m\u1ea1nh m\u1ebd, ph\u00f9 h\u1ee3p cho c\u1ea3 h\u1ecdc t\u1eadp, ph\u00e1t tri\u1ec3n ph\u1ea7n m\u1ec1m l\u1eabn tri\u1ec3n khai h\u1ec7 th\u1ed1ng d\u1eef li\u1ec7u chuy\u00ean nghi\u1ec7p.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Trong thi\u1ebft k\u1ebf c\u01a1 s\u1edf d\u1eef li\u1ec7u, Foreign Key (Kh\u00f3a ngo\u1ea1i) \u0111\u00f3ng vai tr\u00f2 quan tr\u1ecdng gi\u00fap duy tr\u00ec t\u00ednh nh\u1ea5t qu\u00e1n v\u00e0 to\u00e0n v\u1eb9n d\u1eef li\u1ec7u. \u0110\u00e2y l\u00e0 m\u1ed9t trong nh\u1eefng th\u00e0nh ph\u1ea7n then ch\u1ed1t gi\u00fap thi\u1ebft l\u1eadp m\u1ed1i quan h\u1ec7 gi\u1eefa c\u00e1c b\u1ea3ng, t\u1eeb \u0111\u00f3 t\u1ed1i \u01b0u h\u00f3a thao t\u00e1c truy v\u1ea5n v\u00e0<\/p>\n","protected":false},"author":11,"featured_media":28480,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[140],"tags":[],"class_list":["post-28466","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-lap-trinh"],"_links":{"self":[{"href":"https:\/\/interdata.vn\/blog\/wp-json\/wp\/v2\/posts\/28466","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/interdata.vn\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/interdata.vn\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/interdata.vn\/blog\/wp-json\/wp\/v2\/users\/11"}],"replies":[{"embeddable":true,"href":"https:\/\/interdata.vn\/blog\/wp-json\/wp\/v2\/comments?post=28466"}],"version-history":[{"count":8,"href":"https:\/\/interdata.vn\/blog\/wp-json\/wp\/v2\/posts\/28466\/revisions"}],"predecessor-version":[{"id":30172,"href":"https:\/\/interdata.vn\/blog\/wp-json\/wp\/v2\/posts\/28466\/revisions\/30172"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/interdata.vn\/blog\/wp-json\/wp\/v2\/media\/28480"}],"wp:attachment":[{"href":"https:\/\/interdata.vn\/blog\/wp-json\/wp\/v2\/media?parent=28466"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/interdata.vn\/blog\/wp-json\/wp\/v2\/categories?post=28466"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/interdata.vn\/blog\/wp-json\/wp\/v2\/tags?post=28466"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}