\n| 3<\/td>\n | Bob<\/td>\n | Chanh, Qu\u00fdt<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n B\u1ea3ng n\u00e0y vi ph\u1ea1m d\u1ea1ng chu\u1ea9n 1NF v\u00ec c\u1ed9tS\u1ea3n ph\u1ea9m<\/code>ch\u1ee9a danh s\u00e1ch c\u00e1c m\u1ee5c. \u0110\u1ec3 \u0111\u01b0a n\u00f3 v\u00e0o d\u1ea1ng chu\u1ea9n 1NF, ch\u00fang ta chia c\u00e1c s\u1ea3n ph\u1ea9m th\u00e0nh c\u00e1c h\u00e0ng ri\u00eang bi\u1ec7t:<\/p>\n\n\n\n| M\u00e3 \u0111\u01a1n h\u00e0ng<\/th>\n | Kh\u00e1ch h\u00e0ng<\/th>\n | S\u1ea3n ph\u1ea9m<\/th>\n<\/tr>\n<\/thead>\n | \n\n| 1<\/td>\n | John<\/td>\n | T\u00e1o<\/td>\n<\/tr>\n | \n| 1<\/td>\n | John<\/td>\n | Chu\u1ed1i<\/td>\n<\/tr>\n | \n| 1<\/td>\n | John<\/td>\n | Cam<\/td>\n<\/tr>\n | \n| 2<\/td>\n | Alice<\/td>\n | Nho<\/td>\n<\/tr>\n | \n| 2<\/td>\n | Alice<\/td>\n | D\u00e2u t\u00e2y<\/td>\n<\/tr>\n | \n| 3<\/td>\n | Bob<\/td>\n | Chanh<\/td>\n<\/tr>\n | \n| 3<\/td>\n | Bob<\/td>\n | Chanh d\u00e2y<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n B\u00e2y gi\u1edd, m\u1ed7i \u00f4 ch\u1ee9a m\u1ed9t gi\u00e1 tr\u1ecb nguy\u00ean t\u1eed, v\u00e0 b\u1ea3ng \u1edf d\u1ea1ng chu\u1ea9n h\u00f3a th\u1ee9 nh\u1ea5t (1NF).<\/p>\n D\u1ea1ng chu\u1ea9n th\u1ee9 hai (2NF)<\/h2>\nXem x\u00e9t m\u1ed9t b\u1ea3ng l\u01b0u tr\u1eef th\u00f4ng tin v\u1ec1 sinh vi\u00ean v\u00e0 c\u00e1c kh\u00f3a h\u1ecdc c\u1ee7a h\u1ecd:<\/p>\n \n\n\n| M\u00e3 sinh vi\u00ean<\/th>\n | M\u00e3 kh\u00f3a h\u1ecdc<\/th>\n | T\u00ean kh\u00f3a h\u1ecdc<\/th>\n | Gi\u1ea3ng vi\u00ean<\/th>\n<\/tr>\n<\/thead>\n | \n\n| 1<\/td>\n | 101<\/td>\n | To\u00e1n<\/td>\n | Gi\u00e1o s\u01b0 Smith<\/td>\n<\/tr>\n | \n| 1<\/td>\n | 102<\/td>\n | V\u1eadt l\u00fd<\/td>\n | Gi\u00e1o s\u01b0 Johnson<\/td>\n<\/tr>\n | \n| 2<\/td>\n | 101<\/td>\n | To\u00e1n<\/td>\n | Gi\u00e1o s\u01b0 Smith<\/td>\n<\/tr>\n | \n| 3<\/td>\n | 103<\/td>\n | L\u1ecbch s\u1eed<\/td>\n | GS. Davis<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n B\u1ea3ng n\u00e0y vi ph\u1ea1m 2NF v\u00ec thu\u1ed9c t\u00ednh Gi\u1ea3ng vi\u00ean<\/code> thu\u1ed9c t\u00ednh ph\u1ee5 thu\u1ed9c v\u00e0o c\u1ea3 hai M\u00e3 sinh vi\u00ean<\/code> v\u00e0 M\u00e3 m\u00f4n h\u1ecdc<\/code>. \u0110\u1ec3 \u0111\u1ea1t \u0111\u01b0\u1ee3c 2NF, ch\u00fang ta chia b\u1ea3ng th\u00e0nh hai b\u1ea3ng ri\u00eang bi\u1ec7t:<\/p>\nB\u1ea3ng Sinh vi\u00ean:<\/strong><\/p>\n\n\n\n| M\u00e3 sinh vi\u00ean<\/th>\n | T\u00ean sinh vi\u00ean<\/th>\n<\/tr>\n<\/thead>\n | \n\n| 1<\/td>\n | John<\/td>\n<\/tr>\n | \n| 2<\/td>\n | Alice<\/td>\n<\/tr>\n | \n| 3<\/td>\n | Bob<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n B\u1ea3ng M\u00f4n h\u1ecdc:<\/strong><\/p>\n\n\n\n| M\u00e3 m\u00f4n h\u1ecdc<\/th>\n | T\u00ean m\u00f4n h\u1ecdc<\/th>\n | Gi\u1ea3ng vi\u00ean<\/th>\n<\/tr>\n<\/thead>\n | \n\n| 101<\/td>\n | To\u00e1n<\/td>\n | GS. Smith<\/td>\n<\/tr>\n | \n| 102<\/td>\n | V\u1eadt l\u00fd<\/td>\n | GS. Johnson<\/td>\n<\/tr>\n | \n| 103<\/td>\n | L\u1ecbch s\u1eed<\/td>\n | GS. Davis<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n B\u00e2y gi\u1edd, thu\u1ed9c t\u00ednh Gi\u1ea3ng vi\u00ean<\/code> ph\u1ee5 thu\u1ed9c ho\u00e0n to\u00e0n v\u00e0o M\u00e3Kh\u00f3aH\u1ecdc<\/code>, v\u00e0 b\u1ea3ng n\u00e0y \u1edf d\u1ea1ng chu\u1ea9n 2NF.<\/p>\nD\u1ea1ng chu\u1ea9n th\u1ee9 ba (3NF)<\/h2>\nX\u00e9t m\u1ed9t b\u1ea3ng l\u01b0u tr\u1eef th\u00f4ng tin v\u1ec1 nh\u00e2n vi\u00ean v\u00e0 c\u00e1c d\u1ef1 \u00e1n c\u1ee7a h\u1ecd:<\/p>\n \n\n\n| M\u00e3Nh\u00e2nVi\u00ean<\/th>\n | M\u00e3D\u1ef1\u00c1n<\/th>\n | T\u00eanD\u1ef1\u00c1n<\/th>\n | Gi\u00e1m \u0111\u1ed1c<\/th>\n<\/tr>\n<\/thead>\n | \n\n| 1<\/td>\n | 101<\/td>\n | D\u1ef1\u00c1nA<\/td>\n | John<\/td>\n<\/tr>\n | \n| 1<\/td>\n | 102<\/td>\n | D\u1ef1\u00c1nB<\/td>\n | Alice<\/td>\n<\/tr>\n | \n| 2<\/td>\n | 101<\/td>\n | D\u1ef1\u00c1nA<\/td>\n | John<\/td>\n<\/tr>\n | \n| 3<\/td>\n | 103<\/td>\n | D\u1ef1\u00c1nC<\/td>\n | Bob<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n B\u1ea3ng n\u00e0y vi ph\u1ea1m 3NF v\u00ec thu\u1ed9c t\u00ednhQu\u1ea3n l\u00fd<\/code> thu\u1ed9c t\u00ednh ph\u1ee5 thu\u1ed9c v\u00e0o EmployeeID<\/code>, kh\u00f4ng ph\u1ee5 thu\u1ed9c tr\u1ef1c ti\u1ebfp v\u00e0o kh\u00f3a ch\u00ednh. \u0110\u1ec3 \u0111\u01b0a n\u00f3 v\u00e0o d\u1ea1ng chu\u1ea9n 3NF, ch\u00fang ta chia b\u1ea3ng th\u00e0nh hai b\u1ea3ng ri\u00eang bi\u1ec7t:<\/p>\nB\u1ea3ng Nh\u00e2n vi\u00ean:<\/strong><\/p>\n\n\n\n| EmployeeID<\/th>\n | T\u00ean nh\u00e2n vi\u00ean<\/th>\n<\/tr>\n<\/thead>\n | \n\n| 1<\/td>\n | John<\/td>\n<\/tr>\n | \n| 2<\/td>\n | Alice<\/td>\n<\/tr>\n | \n| 3<\/td>\n | Bob<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n B\u1ea3ng D\u1ef1 \u00e1n:<\/strong><\/p>\n\n\n\n| ProjectID<\/th>\n | T\u00ean d\u1ef1 \u00e1n<\/th>\n<\/tr>\n<\/thead>\n | \n\n| 101<\/td>\n | ProjectA<\/td>\n<\/tr>\n | \n| 102<\/td>\n | ProjectB<\/td>\n<\/tr>\n | \n| 103<\/td>\n | ProjectC<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n B\u1ea3ng Nh\u00e2n vi\u00ean_D\u1ef1 \u00e1n:<\/strong><\/p>\n\n\n\n| EmployeeID<\/th>\n | ProjectID<\/th>\n<\/tr>\n<\/thead>\n | \n\n| 1<\/td>\n | 101<\/td>\n<\/tr>\n | \n| 1<\/td>\n | 102<\/td>\n<\/tr>\n | \n| 2<\/td>\n | 101<\/td>\n<\/tr>\n | \n| 3<\/td>\n | 103<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n B\u00e2y gi\u1edd, thu\u1ed9c t\u00ednh Gi\u00e1m \u0111\u1ed1c<\/code> thu\u1ed9c t\u00ednh ph\u1ee5 thu\u1ed9c v\u00e0o ProjectID<\/code>, v\u00e0 b\u1ea3ng n\u00e0y \u1edf d\u1ea1ng chu\u1ea9n 3NF.<\/p>\nD\u1ea1ng chu\u1ea9n Boyce-Codd (BCNF)<\/h2>\nBCNF l\u00e0 phi\u00ean b\u1ea3n nghi\u00eam ng\u1eb7t h\u01a1n c\u1ee7a 3NF. \u0110\u1ec3 minh h\u1ecda BCNF, h\u00e3y xem x\u00e9t m\u1ed9t b\u1ea3ng l\u01b0u tr\u1eef th\u00f4ng tin v\u1ec1 c\u00e1c gi\u00e1o s\u01b0 v\u00e0 c\u00e1c l\u0129nh v\u1ef1c nghi\u00ean c\u1ee9u c\u1ee7a h\u1ecd:<\/p>\n \n\n\n| IDGi\u00e1o s\u01b0<\/th>\n | L\u0129nh v\u1ef1cNghi\u00ean c\u1ee9u<\/th>\n | S\u1ed1V\u0103nPh\u00f2ng<\/th>\n<\/tr>\n<\/thead>\n | \n\n| 1<\/td>\n | Tr\u00ed tu\u1ec7 nh\u00e2n t\u1ea1o<\/td>\n | 101<\/td>\n<\/tr>\n | \n| 2<\/td>\n | H\u1ecdc m\u00e1y<\/td>\n | 102<\/td>\n<\/tr>\n | \n| 3<\/td>\n | Tr\u00ed tu\u1ec7 nh\u00e2n t\u1ea1o<\/td>\n | 103<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n B\u1ea3ng n\u00e0y vi ph\u1ea1m BCNF v\u00ec t\u1ed3n t\u1ea1i m\u1ed9t ph\u1ee5 thu\u1ed9c h\u00e0m phi t\u1ea7m th\u01b0\u1eddng gi\u1eefaL\u0129nh v\u1ef1cNghi\u00ean c\u1ee9u<\/code> v\u00e0 S\u1ed1V\u0103nPh\u00f2ng<\/code> (t\u1ee9c l\u00e0 s\u1ed1 v\u0103n ph\u00f2ng ph\u1ee5 thu\u1ed9c v\u00e0o l\u0129nh v\u1ef1c nghi\u00ean c\u1ee9u). \u0110\u1ec3 \u0111\u1ea1t \u0111\u01b0\u1ee3c BCNF, ch\u00fang ta chia b\u1ea3ng th\u00e0nh hai b\u1ea3ng ri\u00eang bi\u1ec7t:<\/p>\nB\u1ea3ng Gi\u00e1o s\u01b0:<\/strong><\/p>\n\n\n\n| IDGi\u00e1o s\u01b0<\/th>\n | T\u00eanGi\u00e1o s\u01b0<\/th>\n<\/tr>\n<\/thead>\n | \n\n| 1<\/td>\n | GS. Smith<\/td>\n<\/tr>\n | \n| 2<\/td>\n | GS. Johnson<\/td>\n<\/tr>\n | \n| 3<\/td>\n | GS. Davis<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n B\u1ea3ng ResearchAreas:<\/strong><\/p>\n\n\n\n| L\u0129nh v\u1ef1c nghi\u00ean c\u1ee9u<\/th>\n | S\u1ed1 ph\u00f2ng<\/th>\n<\/tr>\n<\/thead>\n | \n\n| Tr\u00ed tu\u1ec7 nh\u00e2n t\u1ea1o<\/td>\n | 101<\/td>\n<\/tr>\n | \n| H\u1ecdc m\u00e1y<\/td>\n | 102<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n B\u1ea3ng ProfessorResearch:<\/strong><\/p>\n\n\n\n| ID Gi\u00e1o s\u01b0<\/th>\n | L\u0129nh v\u1ef1c nghi\u00ean c\u1ee9u<\/th>\n<\/tr>\n<\/thead>\n | \n\n| 1<\/td>\n | Tr\u00ed tu\u1ec7 nh\u00e2n t\u1ea1o<\/td>\n<\/tr>\n | \n| 2<\/td>\n | H\u1ecdc m\u00e1y<\/td>\n<\/tr>\n | \n| 3<\/td>\n | Tr\u00ed tu\u1ec7 nh\u00e2n t\u1ea1o<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n B\u00e2y gi\u1edd, b\u1ea3ng \u0111\u00e3 \u1edf d\u1ea1ng chu\u1ea9n BCNF v\u00ec kh\u00f4ng c\u00f3 ph\u1ee5 thu\u1ed9c h\u00e0m phi t\u1ea7m th\u01b0\u1eddng n\u00e0o.<\/p>\n D\u1ea1ng chu\u1ea9n th\u1ee9 t\u01b0 (4NF)<\/h2>\n4NF x\u1eed l\u00fd c\u00e1c ph\u1ee5 thu\u1ed9c \u0111a gi\u00e1 tr\u1ecb. X\u00e9t m\u1ed9t b\u1ea3ng l\u01b0u tr\u1eef th\u00f4ng tin v\u1ec1 s\u00e1ch v\u00e0 t\u00e1c gi\u1ea3 c\u1ee7a ch\u00fang:<\/p>\n \n\n\n| ID S\u00e1ch<\/th>\n | Ti\u00eau \u0111\u1ec1<\/th>\n | T\u00e1c gi\u1ea3<\/th>\n<\/tr>\n<\/thead>\n | \n\n| 1<\/td>\n | S\u00e1chA<\/td>\n | T\u00e1c gi\u1ea3X, T\u00e1c gi\u1ea3Y<\/td>\n<\/tr>\n | \n| 2<\/td>\n | S\u00e1chB<\/td>\n | T\u00e1c gi\u1ea3Y, T\u00e1c gi\u1ea3Z<\/td>\n<\/tr>\n | \n| 3<\/td>\n | S\u00e1chC<\/td>\n | T\u00e1c gi\u1ea3X<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n B\u1ea3ng n\u00e0y vi ph\u1ea1m 4NF v\u00ec t\u1ed3n t\u1ea1i m\u1ed9t ph\u1ee5 thu\u1ed9c \u0111a gi\u00e1 tr\u1ecb gi\u1eefaBookID<\/code> v\u00e0 T\u00e1c gi\u1ea3<\/code>. \u0110\u1ec3 \u0111\u1ea1t \u0111\u01b0\u1ee3c 4NF, ch\u00fang ta chia b\u1ea3ng th\u00e0nh ba b\u1ea3ng ri\u00eang bi\u1ec7t:<\/p>\nB\u1ea3ng S\u00e1ch:<\/strong><\/p>\n\n\n\n| BookID<\/th>\n | Ti\u00eau \u0111\u1ec1<\/th>\n<\/tr>\n<\/thead>\n | \n\n| 1<\/td>\n | S\u00e1chA<\/td>\n<\/tr>\n | \n| 2<\/td>\n | S\u00e1chB<\/td>\n<\/tr>\n | \n| 3<\/td>\n | S\u00e1chC<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n B\u1ea3ng T\u00e1c gi\u1ea3:<\/strong><\/p>\n\n\n\n| AuthorID<\/th>\n | T\u00ean t\u00e1c gi\u1ea3<\/th>\n<\/tr>\n<\/thead>\n | \n\n| 1<\/td>\n | T\u00e1c gi\u1ea3X<\/td>\n<\/tr>\n | \n| 2<\/td>\n | T\u00e1c gi\u1ea3Y<\/td>\n<\/tr>\n | \n| 3<\/td>\n | T\u00e1c gi\u1ea3Z<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n B\u1ea3ng BookAuthors:<\/strong><\/p>\n\n\n\n| BookID<\/th>\n | AuthorID<\/th>\n<\/tr>\n<\/thead>\n | \n\n| 1<\/td>\n | 1<\/td>\n<\/tr>\n | \n| 1<\/td>\n | 2<\/td>\n<\/tr>\n | \n| 2<\/td>\n | 2<\/td>\n<\/tr>\n | \n| 2<\/td>\n | 3<\/td>\n<\/tr>\n | \n| 3<\/td>\n | 1<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n B\u00e2y gi\u1edd, m\u1ed7i b\u1ea3ng \u0111\u1ec1u \u1edf d\u1ea1ng chu\u1ea9n 4NF, v\u00e0 c\u00e1c ph\u1ee5 thu\u1ed9c \u0111a gi\u00e1 tr\u1ecb \u0111\u00e3 \u0111\u01b0\u1ee3c lo\u1ea1i b\u1ecf.<\/p>\n D\u1ea1ng chu\u1ea9n th\u1ee9 n\u0103m (5NF) ho\u1eb7c D\u1ea1ng chu\u1ea9n k\u1ebft h\u1ee3p-projekt (PJNF)<\/h2>\n5NF ho\u1eb7c PJNF x\u1eed l\u00fd c\u00e1c ph\u1ee5 thu\u1ed9c k\u1ebft h\u1ee3p, n\u1eb1m ngo\u00e0i ph\u1ea1m vi b\u00e0i vi\u1ebft gi\u1edbi thi\u1ec7u n\u00e0y. Vi\u1ec7c \u0111\u1ea1t \u0111\u01b0\u1ee3c 5NF th\u01b0\u1eddng \u0111\u00f2i h\u1ecfi ph\u00e2n r\u00e3 th\u00eam v\u00e0 th\u01b0\u1eddng l\u00e0 c\u1ea7n thi\u1ebft \u0111\u1ed1i v\u1edbi c\u00e1c c\u01a1 s\u1edf d\u1eef li\u1ec7u ph\u1ee9c t\u1ea1p.<\/p>\n K\u1ebft lu\u1eadn<\/h2>\nChu\u1ea9n h\u00f3a c\u01a1 s\u1edf d\u1eef li\u1ec7u l\u00e0 m\u1ed9t qu\u00e1 tr\u00ecnh quan tr\u1ecdng trong thi\u1ebft k\u1ebf c\u01a1 s\u1edf d\u1eef li\u1ec7u, nh\u1eb1m t\u1ed1i \u01b0u h\u00f3a l\u01b0u tr\u1eef d\u1eef li\u1ec7u, c\u1ea3i thi\u1ec7n t\u00ednh to\u00e0n v\u1eb9n d\u1eef li\u1ec7u v\u00e0 gi\u1ea3m thi\u1ec3u c\u00e1c hi\u1ec7n t\u01b0\u1ee3ng b\u1ea5t th\u01b0\u1eddng trong d\u1eef li\u1ec7u. B\u1eb1ng c\u00e1ch t\u1ed5 ch\u1ee9c d\u1eef li\u1ec7u v\u00e0o c\u00e1c b\u1ea3ng \u0111\u00e3 \u0111\u01b0\u1ee3c chu\u1ea9n h\u00f3a, b\u1ea1n c\u00f3 th\u1ec3 n\u00e2ng cao hi\u1ec7u qu\u1ea3 v\u00e0 kh\u1ea3 n\u0103ng b\u1ea3o tr\u00ec c\u1ee7a h\u1ec7 th\u1ed1ng c\u01a1 s\u1edf d\u1eef li\u1ec7u.<\/p>\n H\u00e3y nh\u1edb r\u1eb1ng vi\u1ec7c \u0111\u1ea1t \u0111\u01b0\u1ee3c c\u00e1c d\u1ea1ng chu\u1ea9n cao h\u01a1n, nh\u01b0 BCNF v\u00e0 4NF, kh\u00f4ng ph\u1ea3i l\u00fac n\u00e0o c\u0169ng c\u1ea7n thi\u1ebft \u0111\u1ed1i v\u1edbi m\u1ecdi c\u01a1 s\u1edf d\u1eef li\u1ec7u. M\u1ee9c \u0111\u1ed9 chu\u1ea9n h\u00f3a ph\u1ee5 thu\u1ed9c v\u00e0o c\u00e1c y\u00eau c\u1ea7u c\u1ee5 th\u1ec3 c\u1ee7a \u1ee9ng d\u1ee5ng c\u1ee7a b\u1ea1n v\u00e0 s\u1ef1 \u0111\u00e1nh \u0111\u1ed5i gi\u1eefa t\u00ednh to\u00e0n v\u1eb9n d\u1eef li\u1ec7u v\u00e0 hi\u1ec7u su\u1ea5t.<\/p>\n Khi thi\u1ebft k\u1ebf c\u01a1 s\u1edf d\u1eef li\u1ec7u, \u0111i\u1ec1u quan tr\u1ecdng l\u00e0 ph\u1ea3i t\u00ecm \u0111\u01b0\u1ee3c s\u1ef1 c\u00e2n b\u1eb1ng gi\u1eefa chu\u1ea9n h\u00f3a v\u00e0 t\u00ednh th\u1ef1c ti\u1ec5n. Trong nhi\u1ec1u tr\u01b0\u1eddng h\u1ee3p, \u0111\u1ea1t \u0111\u01b0\u1ee3c d\u1ea1ng chu\u1ea9n 3NF l\u00e0 \u0111\u1ee7 \u0111\u1ec3 \u0111\u1ea3m b\u1ea3o t\u00ednh to\u00e0n v\u1eb9n d\u1eef li\u1ec7u \u0111\u1ed3ng th\u1eddi duy tr\u00ec hi\u1ec7u su\u1ea5t truy v\u1ea5n t\u1ed1t.<\/p>\n Hi\u1ec3u r\u00f5 c\u00e1c nguy\u00ean t\u1eafc chu\u1ea9n h\u00f3a v\u00e0 th\u1ef1c h\u00e0nh ch\u00fang th\u00f4ng qua c\u00e1c v\u00ed d\u1ee5 th\u1ef1c t\u1ebf l\u00e0 \u0111i\u1ec1u c\u1ea7n thi\u1ebft \u0111\u1ed1i v\u1edbi c\u00e1c qu\u1ea3n tr\u1ecb vi\u00ean c\u01a1 s\u1edf d\u1eef li\u1ec7u v\u00e0 nh\u00e0 ph\u00e1t tri\u1ec3n \u0111\u1ec3 t\u1ea1o ra c\u00e1c h\u1ec7 th\u1ed1ng c\u01a1 s\u1edf d\u1eef li\u1ec7u hi\u1ec7u qu\u1ea3 v\u00e0 b\u1ec1n v\u1eefng.<\/p>\n","protected":false},"excerpt":{"rendered":" Gi\u1edbi thi\u1ec7u Chu\u1ea9n h\u00f3a c\u01a1 s\u1edf d\u1eef li\u1ec7u l\u00e0 m\u1ed9t kh\u00e1i ni\u1ec7m quan tr\u1ecdng trong l\u0129nh v\u1ef1c qu\u1ea3n l\u00fd c\u01a1 s\u1edf d\u1eef li\u1ec7u. \u0110\u00e2y l\u00e0 m\u1ed9t qu\u00e1 tr\u00ecnh t\u1ed1i \u01b0u h\u00f3a c\u1ea5u tr\u00fac c\u01a1 s\u1edf d\u1eef li\u1ec7u b\u1eb1ng c\u00e1ch gi\u1ea3m thi\u1ec3u s\u1ef1 tr\u00f9ng l\u1eb7p d\u1eef li\u1ec7u v\u00e0 c\u1ea3i thi\u1ec7n t\u00ednh to\u00e0n v\u1eb9n d\u1eef li\u1ec7u. Chu\u1ea9n h\u00f3a l\u00e0 m\u1ed9t t\u1eadp h\u1ee3p c\u00e1c quy t\u1eafc v\u00e0 h\u01b0\u1edbng d\u1eabn gi\u00fap t\u1ed5 ch\u1ee9c d\u1eef li\u1ec7u m\u1ed9t c\u00e1ch hi\u1ec7u qu\u1ea3 v\u00e0 ng\u0103n ng\u1eeba c\u00e1c l\u1ed7i d\u1eef li\u1ec7u ph\u1ed5 bi\u1ebfn nh\u01b0 l\u1ed7i c\u1eadp nh\u1eadt, l\u1ed7i ch\u00e8n v\u00e0 l\u1ed7i x\u00f3a. Trong b\u00e0i vi\u1ebft n\u00e0y, ch\u00fang t\u00f4i s\u1ebd \u0111i s\u00e2u v\u00e0o c\u00e1c nguy\u00ean t\u1eafc c\u01a1 b\u1ea3n c\u1ee7a chu\u1ea9n h\u00f3a c\u01a1 s\u1edf d\u1eef li\u1ec7u, c\u00e1c d\u1ea1ng chu\u1ea9n h\u00f3a kh\u00e1c nhau v\u00e0 cung c\u1ea5p c\u00e1c v\u00ed d\u1ee5 th\u1ef1c t\u1ebf \u0111\u1ec3 minh h\u1ecda t\u1eebng c\u1ea5p \u0111\u1ed9 chu\u1ea9n h\u00f3a. T\u1ea1i sao c\u1ea7n chu\u1ea9n h\u00f3a c\u01a1 s\u1edf d\u1eef li\u1ec7u? Tr\u01b0\u1edbc khi ch\u00fang ta \u0111i v\u00e0o chi ti\u1ebft v\u1ec1 chu\u1ea9n h\u00f3a c\u01a1 s\u1edf d\u1eef li\u1ec7u, \u0111i\u1ec1u quan tr\u1ecdng l\u00e0 ph\u1ea3i hi\u1ec3u t\u1ea1i sao n\u00f3 l\u1ea1i c\u1ea7n thi\u1ebft. Chu\u1ea9n h\u00f3a mang l\u1ea1i nhi\u1ec1u l\u1ee3i \u00edch: To\u00e0n v\u1eb9n d\u1eef li\u1ec7u:Chu\u1ea9n h\u00f3a gi\u00fap duy tr\u00ec \u0111\u1ed9 ch\u00ednh x\u00e1c v\u00e0 t\u00ednh nh\u1ea5t qu\u00e1n c\u1ee7a d\u1eef li\u1ec7u b\u1eb1ng c\u00e1ch gi\u1ea3m thi\u1ec3u s\u1ef1 tr\u00f9ng l\u1eb7p. Khi d\u1eef li\u1ec7u \u0111\u01b0\u1ee3c l\u01b0u tr\u1eef theo c\u00e1ch kh\u00f4ng l\u1eb7p l\u1ea1i, n\u00f3 \u00edt d\u1ec5 b\u1ecb l\u1ed7i h\u01a1n. L\u01b0u tr\u1eef hi\u1ec7u qu\u1ea3:C\u00e1c c\u01a1 s\u1edf d\u1eef li\u1ec7u \u0111\u00e3 \u0111\u01b0\u1ee3c chu\u1ea9n h\u00f3a th\u01b0\u1eddng chi\u1ebfm \u00edt kh\u00f4ng gian l\u01b0u tr\u1eef h\u01a1n v\u00ec d\u1eef li\u1ec7u tr\u00f9ng l\u1eb7p \u0111\u01b0\u1ee3c gi\u1ea3m thi\u1ec3u. \u0110i\u1ec1u n\u00e0y gi\u00fap gi\u1ea3m chi ph\u00ed l\u01b0u tr\u1eef t\u1ed5ng th\u1ec3. T\u1ed1i \u01b0u h\u00f3a truy v\u1ea5n:C\u00e1c truy v\u1ea5n tr\u1edf n\u00ean hi\u1ec7u qu\u1ea3 h\u01a1n trong c\u00e1c c\u01a1 s\u1edf d\u1eef li\u1ec7u \u0111\u00e3 \u0111\u01b0\u1ee3c chu\u1ea9n h\u00f3a v\u00ec ch\u00fang ch\u1ec9 c\u1ea7n truy c\u1eadp c\u00e1c b\u1ea3ng nh\u1ecf, \u0111\u01b0\u1ee3c c\u1ea5u tr\u00fac t\u1ed1t thay v\u00ec c\u00e1c b\u1ea3ng l\u1edbn, ch\u01b0a chu\u1ea9n h\u00f3a. T\u00ednh linh ho\u1ea1t:C\u00e1c c\u01a1 s\u1edf d\u1eef li\u1ec7u \u0111\u00e3 \u0111\u01b0\u1ee3c chu\u1ea9n h\u00f3a c\u00f3 t\u00ednh linh ho\u1ea1t h\u01a1n khi c\u1ea7n th\u00edch \u1ee9ng v\u1edbi nh\u1eefng thay \u0111\u1ed5i v\u1ec1 y\u00eau c\u1ea7u d\u1eef li\u1ec7u ho\u1eb7c quy t\u1eafc kinh doanh. C\u00e1c c\u1ea5p \u0111\u1ed9 chu\u1ea9n h\u00f3a Chu\u1ea9n h\u00f3a c\u01a1 s\u1edf d\u1eef li\u1ec7u th\u01b0\u1eddng \u0111\u01b0\u1ee3c chia th\u00e0nh nhi\u1ec1u c\u1ea5p \u0111\u1ed9, \u0111\u01b0\u1ee3c g\u1ecdi l\u00e0 c\u00e1c d\u1ea1ng chu\u1ea9n. C\u00e1c d\u1ea1ng chu\u1ea9n th\u01b0\u1eddng \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng nh\u1ea5t l\u00e0: D\u1ea1ng chu\u1ea9n th\u1ee9 nh\u1ea5t (1NF):\u0110\u1ea3m b\u1ea3o r\u1eb1ng m\u1ed7i c\u1ed9t trong b\u1ea3ng ch\u1ee9a c\u00e1c gi\u00e1 tr\u1ecb nguy\u00ean t\u1eed, kh\u00f4ng th\u1ec3 chia nh\u1ecf. Kh\u00f4ng \u0111\u01b0\u1ee3c c\u00f3 c\u00e1c nh\u00f3m l\u1eb7p l\u1ea1i, v\u00e0 m\u1ed7i c\u1ed9t ph\u1ea3i c\u00f3 t\u00ean duy nh\u1ea5t. D\u1ea1ng chu\u1ea9n th\u1ee9 hai (2NF):D\u1ef1a tr\u00ean 1NF, 2NF lo\u1ea1i b\u1ecf c\u00e1c ph\u1ee5 thu\u1ed9c ri\u00eang ph\u1ea7n. M\u1ed9t b\u1ea3ng \u1edf d\u1ea1ng 2NF n\u1ebfu n\u00f3 \u1edf d\u1ea1ng 1NF v\u00e0 t\u1ea5t c\u1ea3 c\u00e1c thu\u1ed9c t\u00ednh kh\u00f4ng kh\u00f3a \u0111\u1ec1u ph\u1ee5 thu\u1ed9c h\u00e0m v\u00e0o to\u00e0n b\u1ed9 kh\u00f3a ch\u00ednh. D\u1ea1ng chu\u1ea9n th\u1ee9 ba (3NF):D\u1ef1a tr\u00ean 2NF, 3NF lo\u1ea1i b\u1ecf c\u00e1c ph\u1ee5 thu\u1ed9c b\u1eafc c\u1ea7u. M\u1ed9t b\u1ea3ng \u1edf d\u1ea1ng 3NF n\u1ebfu n\u00f3 \u1edf d\u1ea1ng 2NF v\u00e0 t\u1ea5t c\u1ea3 c\u00e1c thu\u1ed9c t\u00ednh kh\u00f4ng kh\u00f3a \u0111\u1ec1u ph\u1ee5 thu\u1ed9c h\u00e0m v\u00e0o kh\u00f3a ch\u00ednh, nh\u01b0ng kh\u00f4ng ph\u1ee5 thu\u1ed9c v\u00e0o c\u00e1c thu\u1ed9c t\u00ednh kh\u00f4ng kh\u00f3a kh\u00e1c. D\u1ea1ng chu\u1ea9n Boyce-Codd (BCNF):M\u1ed9t phi\u00ean b\u1ea3n nghi\u00eam ng\u1eb7t h\u01a1n c\u1ee7a 3NF, BCNF \u0111\u1ea3m b\u1ea3o r\u1eb1ng m\u1ecdi ph\u1ee5 thu\u1ed9c h\u00e0m kh\u00f4ng t\u1ea7m th\u01b0\u1eddng \u0111\u1ec1u l\u00e0 si\u00eau kh\u00f3a. \u0110i\u1ec1u n\u00e0y c\u00f3 ngh\u0129a l\u00e0 kh\u00f4ng \u0111\u01b0\u1ee3c ph\u00e9p c\u00f3 c\u00e1c ph\u1ee5 thu\u1ed9c ri\u00eang ph\u1ea7n hay ph\u1ee5 thu\u1ed9c b\u1eafc c\u1ea7u. D\u1ea1ng chu\u1ea9n th\u1ee9 t\u01b0 (4NF):4NF x\u1eed l\u00fd c\u00e1c ph\u1ee5 thu\u1ed9c \u0111a gi\u00e1 tr\u1ecb, n\u01a1i m\u1ed9t thu\u1ed9c t\u00ednh ph\u1ee5 thu\u1ed9c v\u00e0o m\u1ed9t thu\u1ed9c t\u00ednh kh\u00e1c nh\u01b0ng kh\u00f4ng ph\u1ea3i l\u00e0 h\u00e0m c\u1ee7a kh\u00f3a ch\u00ednh. D\u1ea1ng chu\u1ea9n th\u1ee9 n\u0103m (5NF) ho\u1eb7c D\u1ea1ng chu\u1ea9n k\u1ebft h\u1ee3p – chi\u1ebfu (PJNF):C\u00e1c d\u1ea1ng n\u00e0y x\u1eed l\u00fd c\u00e1c tr\u01b0\u1eddng h\u1ee3p m\u00e0 m\u1ed9t b\u1ea3ng \u1edf d\u1ea1ng 4NF, nh\u01b0ng v\u1eabn t\u1ed3n t\u1ea1i c\u00e1c ph\u1ee5 thu\u1ed9c k\u1ebft h\u1ee3p c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c t\u1ed1i \u01b0u h\u00f3a th\u00eam. B\u00e2y gi\u1edd, h\u00e3y minh h\u1ecda c\u00e1c d\u1ea1ng chu\u1ea9n n\u00e0y b\u1eb1ng c\u00e1c v\u00ed d\u1ee5: D\u1ea1ng chu\u1ea9n th\u1ee9 nh\u1ea5t (1NF) Xem x\u00e9t m\u1ed9t b\u1ea3ng ch\u01b0a chu\u1ea9n h\u00f3a l\u01b0u tr\u1eef c\u00e1c \u0111\u01a1n h\u00e0ng c\u1ee7a kh\u00e1ch h\u00e0ng: M\u00e3 \u0111\u01a1n h\u00e0ng Kh\u00e1ch h\u00e0ng S\u1ea3n ph\u1ea9m 1 John T\u00e1o, Chu\u1ed1i, Cam 2 Alice Nho, D\u00e2u t\u00e2y 3 Bob Chanh, Qu\u00fdt B\u1ea3ng n\u00e0y vi ph\u1ea1m d\u1ea1ng chu\u1ea9n 1NF v\u00ec c\u1ed9tS\u1ea3n ph\u1ea9mch\u1ee9a danh s\u00e1ch c\u00e1c m\u1ee5c. \u0110\u1ec3 \u0111\u01b0a n\u00f3 v\u00e0o d\u1ea1ng chu\u1ea9n 1NF, ch\u00fang ta chia c\u00e1c s\u1ea3n ph\u1ea9m th\u00e0nh c\u00e1c h\u00e0ng ri\u00eang bi\u1ec7t: M\u00e3 \u0111\u01a1n h\u00e0ng Kh\u00e1ch h\u00e0ng S\u1ea3n ph\u1ea9m 1 John T\u00e1o 1 John Chu\u1ed1i 1 John Cam 2 Alice Nho 2 Alice D\u00e2u t\u00e2y 3 Bob Chanh 3 Bob Chanh d\u00e2y B\u00e2y gi\u1edd, m\u1ed7i \u00f4 ch\u1ee9a m\u1ed9t gi\u00e1 tr\u1ecb nguy\u00ean t\u1eed, v\u00e0 b\u1ea3ng \u1edf d\u1ea1ng chu\u1ea9n h\u00f3a th\u1ee9 nh\u1ea5t (1NF). D\u1ea1ng chu\u1ea9n th\u1ee9 hai (2NF) Xem x\u00e9t m\u1ed9t b\u1ea3ng l\u01b0u tr\u1eef th\u00f4ng tin v\u1ec1 sinh vi\u00ean v\u00e0 c\u00e1c kh\u00f3a h\u1ecdc c\u1ee7a h\u1ecd: M\u00e3 sinh vi\u00ean M\u00e3 kh\u00f3a h\u1ecdc T\u00ean kh\u00f3a h\u1ecdc Gi\u1ea3ng vi\u00ean 1 101 To\u00e1n Gi\u00e1o s\u01b0 Smith 1 102 V\u1eadt l\u00fd Gi\u00e1o s\u01b0 Johnson 2 101 To\u00e1n Gi\u00e1o s\u01b0 Smith 3 103 L\u1ecbch s\u1eed GS. Davis B\u1ea3ng n\u00e0y vi ph\u1ea1m 2NF v\u00ec thu\u1ed9c t\u00ednh Gi\u1ea3ng vi\u00ean thu\u1ed9c t\u00ednh ph\u1ee5 thu\u1ed9c v\u00e0o c\u1ea3 hai M\u00e3 sinh vi\u00ean v\u00e0 M\u00e3 m\u00f4n h\u1ecdc. \u0110\u1ec3 \u0111\u1ea1t \u0111\u01b0\u1ee3c 2NF, ch\u00fang ta chia b\u1ea3ng th\u00e0nh hai b\u1ea3ng ri\u00eang bi\u1ec7t: B\u1ea3ng Sinh vi\u00ean: M\u00e3 sinh vi\u00ean T\u00ean sinh vi\u00ean 1 John 2 Alice 3 Bob B\u1ea3ng M\u00f4n h\u1ecdc: M\u00e3 m\u00f4n h\u1ecdc T\u00ean m\u00f4n h\u1ecdc Gi\u1ea3ng vi\u00ean 101 To\u00e1n GS. Smith 102 V\u1eadt l\u00fd GS. Johnson 103 L\u1ecbch s\u1eed GS. Davis B\u00e2y gi\u1edd, thu\u1ed9c t\u00ednh Gi\u1ea3ng vi\u00ean ph\u1ee5 thu\u1ed9c ho\u00e0n to\u00e0n v\u00e0o M\u00e3Kh\u00f3aH\u1ecdc, v\u00e0 b\u1ea3ng n\u00e0y \u1edf d\u1ea1ng chu\u1ea9n 2NF. D\u1ea1ng chu\u1ea9n th\u1ee9 ba (3NF) X\u00e9t m\u1ed9t b\u1ea3ng l\u01b0u tr\u1eef th\u00f4ng tin v\u1ec1 nh\u00e2n vi\u00ean v\u00e0 c\u00e1c d\u1ef1 \u00e1n c\u1ee7a h\u1ecd: M\u00e3Nh\u00e2nVi\u00ean M\u00e3D\u1ef1\u00c1n T\u00eanD\u1ef1\u00c1n Gi\u00e1m \u0111\u1ed1c 1 101 D\u1ef1\u00c1nA John 1 102 D\u1ef1\u00c1nB Alice 2 101 D\u1ef1\u00c1nA John 3 103 D\u1ef1\u00c1nC Bob B\u1ea3ng n\u00e0y vi ph\u1ea1m 3NF v\u00ec thu\u1ed9c t\u00ednhQu\u1ea3n l\u00fd thu\u1ed9c t\u00ednh ph\u1ee5 thu\u1ed9c v\u00e0o EmployeeID, kh\u00f4ng ph\u1ee5 thu\u1ed9c tr\u1ef1c ti\u1ebfp v\u00e0o kh\u00f3a ch\u00ednh. \u0110\u1ec3 \u0111\u01b0a n\u00f3 v\u00e0o d\u1ea1ng chu\u1ea9n 3NF, ch\u00fang ta chia b\u1ea3ng th\u00e0nh hai b\u1ea3ng ri\u00eang bi\u1ec7t: B\u1ea3ng Nh\u00e2n vi\u00ean: EmployeeID T\u00ean nh\u00e2n vi\u00ean 1 John 2 AliceH\u01b0\u1edbng d\u1eabn to\u00e0n di\u1ec7n v\u1ec1 chu\u1ea9n h\u00f3a c\u01a1 s\u1edf d\u1eef li\u1ec7u v\u1edbi c\u00e1c v\u00ed d\u1ee5<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":6549,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_yoast_wpseo_title":"","_yoast_wpseo_metadesc":"","_eb_attr":"","neve_meta_sidebar":"","neve_meta_container":"","neve_meta_enable_content_width":"","neve_meta_content_width":0,"neve_meta_title_alignment":"","neve_meta_author_avatar":"","neve_post_elements_order":"","neve_meta_disable_header":"","neve_meta_disable_footer":"","neve_meta_disable_title":"","fifu_image_url":"","fifu_image_alt":"","footnotes":""},"categories":[17],"tags":[],"class_list":["post-6548","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-data-modeling-database"],"yoast_head":"\nH\u01b0\u1edbng d\u1eabn to\u00e0n di\u1ec7n v\u1ec1 chu\u1ea9n h\u00f3a c\u01a1 s\u1edf d\u1eef li\u1ec7u v\u1edbi c\u00e1c v\u00ed d\u1ee5 - Visual Paradigm Guides Vietnamese<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/guides.visual-paradigm.com\/vn\/a-comprehensive-guide-to-database-normalization-with-examples\/\" \/>\n<meta property=\"og:locale\" content=\"vi_VN\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"H\u01b0\u1edbng d\u1eabn to\u00e0n di\u1ec7n v\u1ec1 chu\u1ea9n h\u00f3a c\u01a1 s\u1edf d\u1eef li\u1ec7u v\u1edbi c\u00e1c v\u00ed d\u1ee5 - Visual Paradigm Guides Vietnamese\" \/>\n<meta property=\"og:description\" content=\"Gi\u1edbi thi\u1ec7u Chu\u1ea9n h\u00f3a c\u01a1 s\u1edf d\u1eef li\u1ec7u l\u00e0 m\u1ed9t kh\u00e1i ni\u1ec7m quan tr\u1ecdng trong l\u0129nh v\u1ef1c qu\u1ea3n l\u00fd c\u01a1 s\u1edf d\u1eef li\u1ec7u. \u0110\u00e2y l\u00e0 m\u1ed9t qu\u00e1 tr\u00ecnh t\u1ed1i \u01b0u h\u00f3a c\u1ea5u tr\u00fac c\u01a1 s\u1edf d\u1eef li\u1ec7u b\u1eb1ng c\u00e1ch gi\u1ea3m thi\u1ec3u s\u1ef1 tr\u00f9ng l\u1eb7p d\u1eef li\u1ec7u v\u00e0 c\u1ea3i thi\u1ec7n t\u00ednh to\u00e0n v\u1eb9n d\u1eef li\u1ec7u. Chu\u1ea9n h\u00f3a l\u00e0 m\u1ed9t t\u1eadp h\u1ee3p c\u00e1c quy t\u1eafc v\u00e0 h\u01b0\u1edbng d\u1eabn gi\u00fap t\u1ed5 ch\u1ee9c d\u1eef li\u1ec7u m\u1ed9t c\u00e1ch hi\u1ec7u qu\u1ea3 v\u00e0 ng\u0103n ng\u1eeba c\u00e1c l\u1ed7i d\u1eef li\u1ec7u ph\u1ed5 bi\u1ebfn nh\u01b0 l\u1ed7i c\u1eadp nh\u1eadt, l\u1ed7i ch\u00e8n v\u00e0 l\u1ed7i x\u00f3a. Trong b\u00e0i vi\u1ebft n\u00e0y, ch\u00fang t\u00f4i s\u1ebd \u0111i s\u00e2u v\u00e0o c\u00e1c nguy\u00ean t\u1eafc c\u01a1 b\u1ea3n c\u1ee7a chu\u1ea9n h\u00f3a c\u01a1 s\u1edf d\u1eef li\u1ec7u, c\u00e1c d\u1ea1ng chu\u1ea9n h\u00f3a kh\u00e1c nhau v\u00e0 cung c\u1ea5p c\u00e1c v\u00ed d\u1ee5 th\u1ef1c t\u1ebf \u0111\u1ec3 minh h\u1ecda t\u1eebng c\u1ea5p \u0111\u1ed9 chu\u1ea9n h\u00f3a. T\u1ea1i sao c\u1ea7n chu\u1ea9n h\u00f3a c\u01a1 s\u1edf d\u1eef li\u1ec7u? Tr\u01b0\u1edbc khi ch\u00fang ta \u0111i v\u00e0o chi ti\u1ebft v\u1ec1 chu\u1ea9n h\u00f3a c\u01a1 s\u1edf d\u1eef li\u1ec7u, \u0111i\u1ec1u quan tr\u1ecdng l\u00e0 ph\u1ea3i hi\u1ec3u t\u1ea1i sao n\u00f3 l\u1ea1i c\u1ea7n thi\u1ebft. Chu\u1ea9n h\u00f3a mang l\u1ea1i nhi\u1ec1u l\u1ee3i \u00edch: To\u00e0n v\u1eb9n d\u1eef li\u1ec7u:Chu\u1ea9n h\u00f3a gi\u00fap duy tr\u00ec \u0111\u1ed9 ch\u00ednh x\u00e1c v\u00e0 t\u00ednh nh\u1ea5t qu\u00e1n c\u1ee7a d\u1eef li\u1ec7u b\u1eb1ng c\u00e1ch gi\u1ea3m thi\u1ec3u s\u1ef1 tr\u00f9ng l\u1eb7p. Khi d\u1eef li\u1ec7u \u0111\u01b0\u1ee3c l\u01b0u tr\u1eef theo c\u00e1ch kh\u00f4ng l\u1eb7p l\u1ea1i, n\u00f3 \u00edt d\u1ec5 b\u1ecb l\u1ed7i h\u01a1n. L\u01b0u tr\u1eef hi\u1ec7u qu\u1ea3:C\u00e1c c\u01a1 s\u1edf d\u1eef li\u1ec7u \u0111\u00e3 \u0111\u01b0\u1ee3c chu\u1ea9n h\u00f3a th\u01b0\u1eddng chi\u1ebfm \u00edt kh\u00f4ng gian l\u01b0u tr\u1eef h\u01a1n v\u00ec d\u1eef li\u1ec7u tr\u00f9ng l\u1eb7p \u0111\u01b0\u1ee3c gi\u1ea3m thi\u1ec3u. \u0110i\u1ec1u n\u00e0y gi\u00fap gi\u1ea3m chi ph\u00ed l\u01b0u tr\u1eef t\u1ed5ng th\u1ec3. T\u1ed1i \u01b0u h\u00f3a truy v\u1ea5n:C\u00e1c truy v\u1ea5n tr\u1edf n\u00ean hi\u1ec7u qu\u1ea3 h\u01a1n trong c\u00e1c c\u01a1 s\u1edf d\u1eef li\u1ec7u \u0111\u00e3 \u0111\u01b0\u1ee3c chu\u1ea9n h\u00f3a v\u00ec ch\u00fang ch\u1ec9 c\u1ea7n truy c\u1eadp c\u00e1c b\u1ea3ng nh\u1ecf, \u0111\u01b0\u1ee3c c\u1ea5u tr\u00fac t\u1ed1t thay v\u00ec c\u00e1c b\u1ea3ng l\u1edbn, ch\u01b0a chu\u1ea9n h\u00f3a. T\u00ednh linh ho\u1ea1t:C\u00e1c c\u01a1 s\u1edf d\u1eef li\u1ec7u \u0111\u00e3 \u0111\u01b0\u1ee3c chu\u1ea9n h\u00f3a c\u00f3 t\u00ednh linh ho\u1ea1t h\u01a1n khi c\u1ea7n th\u00edch \u1ee9ng v\u1edbi nh\u1eefng thay \u0111\u1ed5i v\u1ec1 y\u00eau c\u1ea7u d\u1eef li\u1ec7u ho\u1eb7c quy t\u1eafc kinh doanh. C\u00e1c c\u1ea5p \u0111\u1ed9 chu\u1ea9n h\u00f3a Chu\u1ea9n h\u00f3a c\u01a1 s\u1edf d\u1eef li\u1ec7u th\u01b0\u1eddng \u0111\u01b0\u1ee3c chia th\u00e0nh nhi\u1ec1u c\u1ea5p \u0111\u1ed9, \u0111\u01b0\u1ee3c g\u1ecdi l\u00e0 c\u00e1c d\u1ea1ng chu\u1ea9n. C\u00e1c d\u1ea1ng chu\u1ea9n th\u01b0\u1eddng \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng nh\u1ea5t l\u00e0: D\u1ea1ng chu\u1ea9n th\u1ee9 nh\u1ea5t (1NF):\u0110\u1ea3m b\u1ea3o r\u1eb1ng m\u1ed7i c\u1ed9t trong b\u1ea3ng ch\u1ee9a c\u00e1c gi\u00e1 tr\u1ecb nguy\u00ean t\u1eed, kh\u00f4ng th\u1ec3 chia nh\u1ecf. Kh\u00f4ng \u0111\u01b0\u1ee3c c\u00f3 c\u00e1c nh\u00f3m l\u1eb7p l\u1ea1i, v\u00e0 m\u1ed7i c\u1ed9t ph\u1ea3i c\u00f3 t\u00ean duy nh\u1ea5t. D\u1ea1ng chu\u1ea9n th\u1ee9 hai (2NF):D\u1ef1a tr\u00ean 1NF, 2NF lo\u1ea1i b\u1ecf c\u00e1c ph\u1ee5 thu\u1ed9c ri\u00eang ph\u1ea7n. M\u1ed9t b\u1ea3ng \u1edf d\u1ea1ng 2NF n\u1ebfu n\u00f3 \u1edf d\u1ea1ng 1NF v\u00e0 t\u1ea5t c\u1ea3 c\u00e1c thu\u1ed9c t\u00ednh kh\u00f4ng kh\u00f3a \u0111\u1ec1u ph\u1ee5 thu\u1ed9c h\u00e0m v\u00e0o to\u00e0n b\u1ed9 kh\u00f3a ch\u00ednh. D\u1ea1ng chu\u1ea9n th\u1ee9 ba (3NF):D\u1ef1a tr\u00ean 2NF, 3NF lo\u1ea1i b\u1ecf c\u00e1c ph\u1ee5 thu\u1ed9c b\u1eafc c\u1ea7u. M\u1ed9t b\u1ea3ng \u1edf d\u1ea1ng 3NF n\u1ebfu n\u00f3 \u1edf d\u1ea1ng 2NF v\u00e0 t\u1ea5t c\u1ea3 c\u00e1c thu\u1ed9c t\u00ednh kh\u00f4ng kh\u00f3a \u0111\u1ec1u ph\u1ee5 thu\u1ed9c h\u00e0m v\u00e0o kh\u00f3a ch\u00ednh, nh\u01b0ng kh\u00f4ng ph\u1ee5 thu\u1ed9c v\u00e0o c\u00e1c thu\u1ed9c t\u00ednh kh\u00f4ng kh\u00f3a kh\u00e1c. D\u1ea1ng chu\u1ea9n Boyce-Codd (BCNF):M\u1ed9t phi\u00ean b\u1ea3n nghi\u00eam ng\u1eb7t h\u01a1n c\u1ee7a 3NF, BCNF \u0111\u1ea3m b\u1ea3o r\u1eb1ng m\u1ecdi ph\u1ee5 thu\u1ed9c h\u00e0m kh\u00f4ng t\u1ea7m th\u01b0\u1eddng \u0111\u1ec1u l\u00e0 si\u00eau kh\u00f3a. \u0110i\u1ec1u n\u00e0y c\u00f3 ngh\u0129a l\u00e0 kh\u00f4ng \u0111\u01b0\u1ee3c ph\u00e9p c\u00f3 c\u00e1c ph\u1ee5 thu\u1ed9c ri\u00eang ph\u1ea7n hay ph\u1ee5 thu\u1ed9c b\u1eafc c\u1ea7u. D\u1ea1ng chu\u1ea9n th\u1ee9 t\u01b0 (4NF):4NF x\u1eed l\u00fd c\u00e1c ph\u1ee5 thu\u1ed9c \u0111a gi\u00e1 tr\u1ecb, n\u01a1i m\u1ed9t thu\u1ed9c t\u00ednh ph\u1ee5 thu\u1ed9c v\u00e0o m\u1ed9t thu\u1ed9c t\u00ednh kh\u00e1c nh\u01b0ng kh\u00f4ng ph\u1ea3i l\u00e0 h\u00e0m c\u1ee7a kh\u00f3a ch\u00ednh. D\u1ea1ng chu\u1ea9n th\u1ee9 n\u0103m (5NF) ho\u1eb7c D\u1ea1ng chu\u1ea9n k\u1ebft h\u1ee3p – chi\u1ebfu (PJNF):C\u00e1c d\u1ea1ng n\u00e0y x\u1eed l\u00fd c\u00e1c tr\u01b0\u1eddng h\u1ee3p m\u00e0 m\u1ed9t b\u1ea3ng \u1edf d\u1ea1ng 4NF, nh\u01b0ng v\u1eabn t\u1ed3n t\u1ea1i c\u00e1c ph\u1ee5 thu\u1ed9c k\u1ebft h\u1ee3p c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c t\u1ed1i \u01b0u h\u00f3a th\u00eam. B\u00e2y gi\u1edd, h\u00e3y minh h\u1ecda c\u00e1c d\u1ea1ng chu\u1ea9n n\u00e0y b\u1eb1ng c\u00e1c v\u00ed d\u1ee5: D\u1ea1ng chu\u1ea9n th\u1ee9 nh\u1ea5t (1NF) Xem x\u00e9t m\u1ed9t b\u1ea3ng ch\u01b0a chu\u1ea9n h\u00f3a l\u01b0u tr\u1eef c\u00e1c \u0111\u01a1n h\u00e0ng c\u1ee7a kh\u00e1ch h\u00e0ng: M\u00e3 \u0111\u01a1n h\u00e0ng Kh\u00e1ch h\u00e0ng S\u1ea3n ph\u1ea9m 1 John T\u00e1o, Chu\u1ed1i, Cam 2 Alice Nho, D\u00e2u t\u00e2y 3 Bob Chanh, Qu\u00fdt B\u1ea3ng n\u00e0y vi ph\u1ea1m d\u1ea1ng chu\u1ea9n 1NF v\u00ec c\u1ed9tS\u1ea3n ph\u1ea9mch\u1ee9a danh s\u00e1ch c\u00e1c m\u1ee5c. \u0110\u1ec3 \u0111\u01b0a n\u00f3 v\u00e0o d\u1ea1ng chu\u1ea9n 1NF, ch\u00fang ta chia c\u00e1c s\u1ea3n ph\u1ea9m th\u00e0nh c\u00e1c h\u00e0ng ri\u00eang bi\u1ec7t: M\u00e3 \u0111\u01a1n h\u00e0ng Kh\u00e1ch h\u00e0ng S\u1ea3n ph\u1ea9m 1 John T\u00e1o 1 John Chu\u1ed1i 1 John Cam 2 Alice Nho 2 Alice D\u00e2u t\u00e2y 3 Bob Chanh 3 Bob Chanh d\u00e2y B\u00e2y gi\u1edd, m\u1ed7i \u00f4 ch\u1ee9a m\u1ed9t gi\u00e1 tr\u1ecb nguy\u00ean t\u1eed, v\u00e0 b\u1ea3ng \u1edf d\u1ea1ng chu\u1ea9n h\u00f3a th\u1ee9 nh\u1ea5t (1NF). D\u1ea1ng chu\u1ea9n th\u1ee9 hai (2NF) Xem x\u00e9t m\u1ed9t b\u1ea3ng l\u01b0u tr\u1eef th\u00f4ng tin v\u1ec1 sinh vi\u00ean v\u00e0 c\u00e1c kh\u00f3a h\u1ecdc c\u1ee7a h\u1ecd: M\u00e3 sinh vi\u00ean M\u00e3 kh\u00f3a h\u1ecdc T\u00ean kh\u00f3a h\u1ecdc Gi\u1ea3ng vi\u00ean 1 101 To\u00e1n Gi\u00e1o s\u01b0 Smith 1 102 V\u1eadt l\u00fd Gi\u00e1o s\u01b0 Johnson 2 101 To\u00e1n Gi\u00e1o s\u01b0 Smith 3 103 L\u1ecbch s\u1eed GS. Davis B\u1ea3ng n\u00e0y vi ph\u1ea1m 2NF v\u00ec thu\u1ed9c t\u00ednh Gi\u1ea3ng vi\u00ean thu\u1ed9c t\u00ednh ph\u1ee5 thu\u1ed9c v\u00e0o c\u1ea3 hai M\u00e3 sinh vi\u00ean v\u00e0 M\u00e3 m\u00f4n h\u1ecdc. \u0110\u1ec3 \u0111\u1ea1t \u0111\u01b0\u1ee3c 2NF, ch\u00fang ta chia b\u1ea3ng th\u00e0nh hai b\u1ea3ng ri\u00eang bi\u1ec7t: B\u1ea3ng Sinh vi\u00ean: M\u00e3 sinh vi\u00ean T\u00ean sinh vi\u00ean 1 John 2 Alice 3 Bob B\u1ea3ng M\u00f4n h\u1ecdc: M\u00e3 m\u00f4n h\u1ecdc T\u00ean m\u00f4n h\u1ecdc Gi\u1ea3ng vi\u00ean 101 To\u00e1n GS. Smith 102 V\u1eadt l\u00fd GS. Johnson 103 L\u1ecbch s\u1eed GS. Davis B\u00e2y gi\u1edd, thu\u1ed9c t\u00ednh Gi\u1ea3ng vi\u00ean ph\u1ee5 thu\u1ed9c ho\u00e0n to\u00e0n v\u00e0o M\u00e3Kh\u00f3aH\u1ecdc, v\u00e0 b\u1ea3ng n\u00e0y \u1edf d\u1ea1ng chu\u1ea9n 2NF. D\u1ea1ng chu\u1ea9n th\u1ee9 ba (3NF) X\u00e9t m\u1ed9t b\u1ea3ng l\u01b0u tr\u1eef th\u00f4ng tin v\u1ec1 nh\u00e2n vi\u00ean v\u00e0 c\u00e1c d\u1ef1 \u00e1n c\u1ee7a h\u1ecd: M\u00e3Nh\u00e2nVi\u00ean M\u00e3D\u1ef1\u00c1n T\u00eanD\u1ef1\u00c1n Gi\u00e1m \u0111\u1ed1c 1 101 D\u1ef1\u00c1nA John 1 102 D\u1ef1\u00c1nB Alice 2 101 D\u1ef1\u00c1nA John 3 103 D\u1ef1\u00c1nC Bob B\u1ea3ng n\u00e0y vi ph\u1ea1m 3NF v\u00ec thu\u1ed9c t\u00ednhQu\u1ea3n l\u00fd thu\u1ed9c t\u00ednh ph\u1ee5 thu\u1ed9c v\u00e0o EmployeeID, kh\u00f4ng ph\u1ee5 thu\u1ed9c tr\u1ef1c ti\u1ebfp v\u00e0o kh\u00f3a ch\u00ednh. \u0110\u1ec3 \u0111\u01b0a n\u00f3 v\u00e0o d\u1ea1ng chu\u1ea9n 3NF, ch\u00fang ta chia b\u1ea3ng th\u00e0nh hai b\u1ea3ng ri\u00eang bi\u1ec7t: B\u1ea3ng Nh\u00e2n vi\u00ean: EmployeeID T\u00ean nh\u00e2n vi\u00ean 1 John 2 AliceH\u01b0\u1edbng d\u1eabn to\u00e0n di\u1ec7n v\u1ec1 chu\u1ea9n h\u00f3a c\u01a1 s\u1edf d\u1eef li\u1ec7u v\u1edbi c\u00e1c v\u00ed d\u1ee5\" \/>\n<meta property=\"og:url\" content=\"https:\/\/guides.visual-paradigm.com\/vn\/a-comprehensive-guide-to-database-normalization-with-examples\/\" \/>\n<meta property=\"og:site_name\" content=\"Visual Paradigm Guides Vietnamese\" \/>\n<meta property=\"article:published_time\" content=\"2026-02-05T01:46:53+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/guides.visual-paradigm.com\/vn\/wp-content\/uploads\/sites\/10\/2026\/02\/img_6503eac4b1cdf.png\" \/>\n\t<meta property=\"og:image:width\" content=\"1323\" \/>\n\t<meta property=\"og:image:height\" content=\"378\" \/>\n\t<meta property=\"og:image:type\" content=\"image\/png\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"\u0110\u01b0\u1ee3c vi\u1ebft b\u1edfi\" \/>\n\t<meta name=\"twitter:data1\" content=\"vpadmin\" \/>\n\t<meta name=\"twitter:label2\" content=\"\u01af\u1edbc t\u00ednh th\u1eddi gian \u0111\u1ecdc\" \/>\n\t<meta name=\"twitter:data2\" content=\"6 ph\u00fat\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\/\/guides.visual-paradigm.com\/vn\/a-comprehensive-guide-to-database-normalization-with-examples\/#article\",\"isPartOf\":{\"@id\":\"https:\/\/guides.visual-paradigm.com\/vn\/a-comprehensive-guide-to-database-normalization-with-examples\/\"},\"headline\":\"H\u01b0\u1edbng d\u1eabn to\u00e0n di\u1ec7n v\u1ec1 chu\u1ea9n h\u00f3a c\u01a1 s\u1edf d\u1eef li\u1ec7u v\u1edbi c\u00e1c v\u00ed d\u1ee5\",\"datePublished\":\"2026-02-05T01:46:53+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\/\/guides.visual-paradigm.com\/vn\/a-comprehensive-guide-to-database-normalization-with-examples\/\"},\"wordCount\":2512,\"commentCount\":0,\"image\":{\"@id\":\"https:\/\/guides.visual-paradigm.com\/vn\/a-comprehensive-guide-to-database-normalization-with-examples\/#primaryimage\"},\"thumbnailUrl\":\"https:\/\/guides.visual-paradigm.com\/vn\/wp-content\/uploads\/sites\/10\/2026\/02\/img_6503eac4b1cdf.png\",\"articleSection\":[\"Data Modeling \/ Database\"],\"inLanguage\":\"vi\",\"potentialAction\":[{\"@type\":\"CommentAction\",\"name\":\"Comment\",\"target\":[\"https:\/\/guides.visual-paradigm.com\/vn\/a-comprehensive-guide-to-database-normalization-with-examples\/#respond\"]}]},{\"@type\":\"WebPage\",\"@id\":\"https:\/\/guides.visual-paradigm.com\/vn\/a-comprehensive-guide-to-database-normalization-with-examples\/\",\"url\":\"https:\/\/guides.visual-paradigm.com\/vn\/a-comprehensive-guide-to-database-normalization-with-examples\/\",\"name\":\"H\u01b0\u1edbng d\u1eabn to\u00e0n di\u1ec7n v\u1ec1 chu\u1ea9n h\u00f3a c\u01a1 s\u1edf d\u1eef li\u1ec7u v\u1edbi c\u00e1c v\u00ed d\u1ee5 - 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Chu\u1ea9n h\u00f3a l\u00e0 m\u1ed9t t\u1eadp h\u1ee3p c\u00e1c quy t\u1eafc v\u00e0 h\u01b0\u1edbng d\u1eabn gi\u00fap t\u1ed5 ch\u1ee9c d\u1eef li\u1ec7u m\u1ed9t c\u00e1ch hi\u1ec7u qu\u1ea3 v\u00e0 ng\u0103n ng\u1eeba c\u00e1c l\u1ed7i d\u1eef li\u1ec7u ph\u1ed5 bi\u1ebfn nh\u01b0 l\u1ed7i c\u1eadp nh\u1eadt, l\u1ed7i ch\u00e8n v\u00e0 l\u1ed7i x\u00f3a. Trong b\u00e0i vi\u1ebft n\u00e0y, ch\u00fang t\u00f4i s\u1ebd \u0111i s\u00e2u v\u00e0o c\u00e1c nguy\u00ean t\u1eafc c\u01a1 b\u1ea3n c\u1ee7a chu\u1ea9n h\u00f3a c\u01a1 s\u1edf d\u1eef li\u1ec7u, c\u00e1c d\u1ea1ng chu\u1ea9n h\u00f3a kh\u00e1c nhau v\u00e0 cung c\u1ea5p c\u00e1c v\u00ed d\u1ee5 th\u1ef1c t\u1ebf \u0111\u1ec3 minh h\u1ecda t\u1eebng c\u1ea5p \u0111\u1ed9 chu\u1ea9n h\u00f3a. T\u1ea1i sao c\u1ea7n chu\u1ea9n h\u00f3a c\u01a1 s\u1edf d\u1eef li\u1ec7u? Tr\u01b0\u1edbc khi ch\u00fang ta \u0111i v\u00e0o chi ti\u1ebft v\u1ec1 chu\u1ea9n h\u00f3a c\u01a1 s\u1edf d\u1eef li\u1ec7u, \u0111i\u1ec1u quan tr\u1ecdng l\u00e0 ph\u1ea3i hi\u1ec3u t\u1ea1i sao n\u00f3 l\u1ea1i c\u1ea7n thi\u1ebft. Chu\u1ea9n h\u00f3a mang l\u1ea1i nhi\u1ec1u l\u1ee3i \u00edch: To\u00e0n v\u1eb9n d\u1eef li\u1ec7u:Chu\u1ea9n h\u00f3a gi\u00fap duy tr\u00ec \u0111\u1ed9 ch\u00ednh x\u00e1c v\u00e0 t\u00ednh nh\u1ea5t qu\u00e1n c\u1ee7a d\u1eef li\u1ec7u b\u1eb1ng c\u00e1ch gi\u1ea3m thi\u1ec3u s\u1ef1 tr\u00f9ng l\u1eb7p. Khi d\u1eef li\u1ec7u \u0111\u01b0\u1ee3c l\u01b0u tr\u1eef theo c\u00e1ch kh\u00f4ng l\u1eb7p l\u1ea1i, n\u00f3 \u00edt d\u1ec5 b\u1ecb l\u1ed7i h\u01a1n. L\u01b0u tr\u1eef hi\u1ec7u qu\u1ea3:C\u00e1c c\u01a1 s\u1edf d\u1eef li\u1ec7u \u0111\u00e3 \u0111\u01b0\u1ee3c chu\u1ea9n h\u00f3a th\u01b0\u1eddng chi\u1ebfm \u00edt kh\u00f4ng gian l\u01b0u tr\u1eef h\u01a1n v\u00ec d\u1eef li\u1ec7u tr\u00f9ng l\u1eb7p \u0111\u01b0\u1ee3c gi\u1ea3m thi\u1ec3u. \u0110i\u1ec1u n\u00e0y gi\u00fap gi\u1ea3m chi ph\u00ed l\u01b0u tr\u1eef t\u1ed5ng th\u1ec3. T\u1ed1i \u01b0u h\u00f3a truy v\u1ea5n:C\u00e1c truy v\u1ea5n tr\u1edf n\u00ean hi\u1ec7u qu\u1ea3 h\u01a1n trong c\u00e1c c\u01a1 s\u1edf d\u1eef li\u1ec7u \u0111\u00e3 \u0111\u01b0\u1ee3c chu\u1ea9n h\u00f3a v\u00ec ch\u00fang ch\u1ec9 c\u1ea7n truy c\u1eadp c\u00e1c b\u1ea3ng nh\u1ecf, \u0111\u01b0\u1ee3c c\u1ea5u tr\u00fac t\u1ed1t thay v\u00ec c\u00e1c b\u1ea3ng l\u1edbn, ch\u01b0a chu\u1ea9n h\u00f3a. T\u00ednh linh ho\u1ea1t:C\u00e1c c\u01a1 s\u1edf d\u1eef li\u1ec7u \u0111\u00e3 \u0111\u01b0\u1ee3c chu\u1ea9n h\u00f3a c\u00f3 t\u00ednh linh ho\u1ea1t h\u01a1n khi c\u1ea7n th\u00edch \u1ee9ng v\u1edbi nh\u1eefng thay \u0111\u1ed5i v\u1ec1 y\u00eau c\u1ea7u d\u1eef li\u1ec7u ho\u1eb7c quy t\u1eafc kinh doanh. C\u00e1c c\u1ea5p \u0111\u1ed9 chu\u1ea9n h\u00f3a Chu\u1ea9n h\u00f3a c\u01a1 s\u1edf d\u1eef li\u1ec7u th\u01b0\u1eddng \u0111\u01b0\u1ee3c chia th\u00e0nh nhi\u1ec1u c\u1ea5p \u0111\u1ed9, \u0111\u01b0\u1ee3c g\u1ecdi l\u00e0 c\u00e1c d\u1ea1ng chu\u1ea9n. C\u00e1c d\u1ea1ng chu\u1ea9n th\u01b0\u1eddng \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng nh\u1ea5t l\u00e0: D\u1ea1ng chu\u1ea9n th\u1ee9 nh\u1ea5t (1NF):\u0110\u1ea3m b\u1ea3o r\u1eb1ng m\u1ed7i c\u1ed9t trong b\u1ea3ng ch\u1ee9a c\u00e1c gi\u00e1 tr\u1ecb nguy\u00ean t\u1eed, kh\u00f4ng th\u1ec3 chia nh\u1ecf. Kh\u00f4ng \u0111\u01b0\u1ee3c c\u00f3 c\u00e1c nh\u00f3m l\u1eb7p l\u1ea1i, v\u00e0 m\u1ed7i c\u1ed9t ph\u1ea3i c\u00f3 t\u00ean duy nh\u1ea5t. D\u1ea1ng chu\u1ea9n th\u1ee9 hai (2NF):D\u1ef1a tr\u00ean 1NF, 2NF lo\u1ea1i b\u1ecf c\u00e1c ph\u1ee5 thu\u1ed9c ri\u00eang ph\u1ea7n. M\u1ed9t b\u1ea3ng \u1edf d\u1ea1ng 2NF n\u1ebfu n\u00f3 \u1edf d\u1ea1ng 1NF v\u00e0 t\u1ea5t c\u1ea3 c\u00e1c thu\u1ed9c t\u00ednh kh\u00f4ng kh\u00f3a \u0111\u1ec1u ph\u1ee5 thu\u1ed9c h\u00e0m v\u00e0o to\u00e0n b\u1ed9 kh\u00f3a ch\u00ednh. D\u1ea1ng chu\u1ea9n th\u1ee9 ba (3NF):D\u1ef1a tr\u00ean 2NF, 3NF lo\u1ea1i b\u1ecf c\u00e1c ph\u1ee5 thu\u1ed9c b\u1eafc c\u1ea7u. M\u1ed9t b\u1ea3ng \u1edf d\u1ea1ng 3NF n\u1ebfu n\u00f3 \u1edf d\u1ea1ng 2NF v\u00e0 t\u1ea5t c\u1ea3 c\u00e1c thu\u1ed9c t\u00ednh kh\u00f4ng kh\u00f3a \u0111\u1ec1u ph\u1ee5 thu\u1ed9c h\u00e0m v\u00e0o kh\u00f3a ch\u00ednh, nh\u01b0ng kh\u00f4ng ph\u1ee5 thu\u1ed9c v\u00e0o c\u00e1c thu\u1ed9c t\u00ednh kh\u00f4ng kh\u00f3a kh\u00e1c. D\u1ea1ng chu\u1ea9n Boyce-Codd (BCNF):M\u1ed9t phi\u00ean b\u1ea3n nghi\u00eam ng\u1eb7t h\u01a1n c\u1ee7a 3NF, BCNF \u0111\u1ea3m b\u1ea3o r\u1eb1ng m\u1ecdi ph\u1ee5 thu\u1ed9c h\u00e0m kh\u00f4ng t\u1ea7m th\u01b0\u1eddng \u0111\u1ec1u l\u00e0 si\u00eau kh\u00f3a. \u0110i\u1ec1u n\u00e0y c\u00f3 ngh\u0129a l\u00e0 kh\u00f4ng \u0111\u01b0\u1ee3c ph\u00e9p c\u00f3 c\u00e1c ph\u1ee5 thu\u1ed9c ri\u00eang ph\u1ea7n hay ph\u1ee5 thu\u1ed9c b\u1eafc c\u1ea7u. D\u1ea1ng chu\u1ea9n th\u1ee9 t\u01b0 (4NF):4NF x\u1eed l\u00fd c\u00e1c ph\u1ee5 thu\u1ed9c \u0111a gi\u00e1 tr\u1ecb, n\u01a1i m\u1ed9t thu\u1ed9c t\u00ednh ph\u1ee5 thu\u1ed9c v\u00e0o m\u1ed9t thu\u1ed9c t\u00ednh kh\u00e1c nh\u01b0ng kh\u00f4ng ph\u1ea3i l\u00e0 h\u00e0m c\u1ee7a kh\u00f3a ch\u00ednh. D\u1ea1ng chu\u1ea9n th\u1ee9 n\u0103m (5NF) ho\u1eb7c D\u1ea1ng chu\u1ea9n k\u1ebft h\u1ee3p – chi\u1ebfu (PJNF):C\u00e1c d\u1ea1ng n\u00e0y x\u1eed l\u00fd c\u00e1c tr\u01b0\u1eddng h\u1ee3p m\u00e0 m\u1ed9t b\u1ea3ng \u1edf d\u1ea1ng 4NF, nh\u01b0ng v\u1eabn t\u1ed3n t\u1ea1i c\u00e1c ph\u1ee5 thu\u1ed9c k\u1ebft h\u1ee3p c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c t\u1ed1i \u01b0u h\u00f3a th\u00eam. B\u00e2y gi\u1edd, h\u00e3y minh h\u1ecda c\u00e1c d\u1ea1ng chu\u1ea9n n\u00e0y b\u1eb1ng c\u00e1c v\u00ed d\u1ee5: D\u1ea1ng chu\u1ea9n th\u1ee9 nh\u1ea5t (1NF) Xem x\u00e9t m\u1ed9t b\u1ea3ng ch\u01b0a chu\u1ea9n h\u00f3a l\u01b0u tr\u1eef c\u00e1c \u0111\u01a1n h\u00e0ng c\u1ee7a kh\u00e1ch h\u00e0ng: M\u00e3 \u0111\u01a1n h\u00e0ng Kh\u00e1ch h\u00e0ng S\u1ea3n ph\u1ea9m 1 John T\u00e1o, Chu\u1ed1i, Cam 2 Alice Nho, D\u00e2u t\u00e2y 3 Bob Chanh, Qu\u00fdt B\u1ea3ng n\u00e0y vi ph\u1ea1m d\u1ea1ng chu\u1ea9n 1NF v\u00ec c\u1ed9tS\u1ea3n ph\u1ea9mch\u1ee9a danh s\u00e1ch c\u00e1c m\u1ee5c. \u0110\u1ec3 \u0111\u01b0a n\u00f3 v\u00e0o d\u1ea1ng chu\u1ea9n 1NF, ch\u00fang ta chia c\u00e1c s\u1ea3n ph\u1ea9m th\u00e0nh c\u00e1c h\u00e0ng ri\u00eang bi\u1ec7t: M\u00e3 \u0111\u01a1n h\u00e0ng Kh\u00e1ch h\u00e0ng S\u1ea3n ph\u1ea9m 1 John T\u00e1o 1 John Chu\u1ed1i 1 John Cam 2 Alice Nho 2 Alice D\u00e2u t\u00e2y 3 Bob Chanh 3 Bob Chanh d\u00e2y B\u00e2y gi\u1edd, m\u1ed7i \u00f4 ch\u1ee9a m\u1ed9t gi\u00e1 tr\u1ecb nguy\u00ean t\u1eed, v\u00e0 b\u1ea3ng \u1edf d\u1ea1ng chu\u1ea9n h\u00f3a th\u1ee9 nh\u1ea5t (1NF). D\u1ea1ng chu\u1ea9n th\u1ee9 hai (2NF) Xem x\u00e9t m\u1ed9t b\u1ea3ng l\u01b0u tr\u1eef th\u00f4ng tin v\u1ec1 sinh vi\u00ean v\u00e0 c\u00e1c kh\u00f3a h\u1ecdc c\u1ee7a h\u1ecd: M\u00e3 sinh vi\u00ean M\u00e3 kh\u00f3a h\u1ecdc T\u00ean kh\u00f3a h\u1ecdc Gi\u1ea3ng vi\u00ean 1 101 To\u00e1n Gi\u00e1o s\u01b0 Smith 1 102 V\u1eadt l\u00fd Gi\u00e1o s\u01b0 Johnson 2 101 To\u00e1n Gi\u00e1o s\u01b0 Smith 3 103 L\u1ecbch s\u1eed GS. Davis B\u1ea3ng n\u00e0y vi ph\u1ea1m 2NF v\u00ec thu\u1ed9c t\u00ednh Gi\u1ea3ng vi\u00ean thu\u1ed9c t\u00ednh ph\u1ee5 thu\u1ed9c v\u00e0o c\u1ea3 hai M\u00e3 sinh vi\u00ean v\u00e0 M\u00e3 m\u00f4n h\u1ecdc. \u0110\u1ec3 \u0111\u1ea1t \u0111\u01b0\u1ee3c 2NF, ch\u00fang ta chia b\u1ea3ng th\u00e0nh hai b\u1ea3ng ri\u00eang bi\u1ec7t: B\u1ea3ng Sinh vi\u00ean: M\u00e3 sinh vi\u00ean T\u00ean sinh vi\u00ean 1 John 2 Alice 3 Bob B\u1ea3ng M\u00f4n h\u1ecdc: M\u00e3 m\u00f4n h\u1ecdc T\u00ean m\u00f4n h\u1ecdc Gi\u1ea3ng vi\u00ean 101 To\u00e1n GS. Smith 102 V\u1eadt l\u00fd GS. Johnson 103 L\u1ecbch s\u1eed GS. Davis B\u00e2y gi\u1edd, thu\u1ed9c t\u00ednh Gi\u1ea3ng vi\u00ean ph\u1ee5 thu\u1ed9c ho\u00e0n to\u00e0n v\u00e0o M\u00e3Kh\u00f3aH\u1ecdc, v\u00e0 b\u1ea3ng n\u00e0y \u1edf d\u1ea1ng chu\u1ea9n 2NF. 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