{"id":51,"date":"2026-04-07T16:17:17","date_gmt":"2026-04-07T16:17:17","guid":{"rendered":"https:\/\/www.we-notes.com\/vn\/er-diagram-data-redundancy-legacy-migration\/"},"modified":"2026-04-07T16:17:17","modified_gmt":"2026-04-07T16:17:17","slug":"er-diagram-data-redundancy-legacy-migration","status":"publish","type":"post","link":"https:\/\/www.we-notes.com\/vn\/er-diagram-data-redundancy-legacy-migration\/","title":{"rendered":"Nghi\u00ean c\u1ee9u tr\u01b0\u1eddng h\u1ee3p: C\u00e1ch m\u1ed9t s\u01a1 \u0111\u1ed3 ER ph\u1ee9c t\u1ea1p \u0111\u00e3 gi\u1ea3i quy\u1ebft v\u1ea5n \u0111\u1ec1 tr\u00f9ng l\u1eb7p d\u1eef li\u1ec7u trong qu\u00e1 tr\u00ecnh di d\u1eddi h\u1ec7 th\u1ed1ng c\u0169"},"content":{"rendered":"

Trong th\u1ebf gi\u1edbi ki\u1ebfn tr\u00fac d\u1eef li\u1ec7u, \u00edt th\u00e1ch th\u1ee9c n\u00e0o dai d\u1eb3ng b\u1eb1ng v\u1ea5n \u0111\u1ec1 tr\u00f9ng l\u1eb7p d\u1eef li\u1ec7u trong c\u00e1c h\u1ec7 th\u1ed1ng c\u0169. Khi c\u00e1c t\u1ed5 ch\u1ee9c n\u1ed7 l\u1ef1c hi\u1ec7n \u0111\u1ea1i h\u00f3a c\u01a1 s\u1edf h\u1ea1 t\u1ea7ng c\u1ee7a m\u00ecnh, kh\u1ed1i l\u01b0\u1ee3ng d\u1eef li\u1ec7u b\u1ecb tr\u00f9ng l\u1eb7p, kh\u00f4ng nh\u1ea5t qu\u00e1n v\u00e0 b\u1ecb b\u1ecf r\u01a1i th\u01b0\u1eddng tr\u1edf th\u00e0nh r\u00e0o c\u1ea3n ch\u00ednh. Nghi\u00ean c\u1ee9u tr\u01b0\u1eddng h\u1ee3p n\u00e0y xem x\u00e9t m\u1ed9t t\u00ecnh hu\u1ed1ng th\u1ef1c t\u1ebf, n\u01a1i s\u01a1 \u0111\u1ed3 quan h\u1ec7 th\u1ef1c th\u1ec3 (ERD) chi ti\u1ebft \u0111\u00e3 \u0111\u00f3ng vai tr\u00f2 l\u00e0 b\u1ea3n thi\u1ebft k\u1ebf \u0111\u1ec3 gi\u1ea3i quy\u1ebft c\u00e1c v\u1ea5n \u0111\u1ec1 nghi\u00eam tr\u1ecdng v\u1ec1 t\u00ednh to\u00e0n v\u1eb9n d\u1eef li\u1ec7u trong m\u1ed9t d\u1ef1 \u00e1n di d\u1eddi l\u1edbn.<\/p>\n

M\u1ee5c ti\u00eau l\u00e0 r\u00f5 r\u00e0ng: chuy\u1ec3n \u0111\u1ed5i t\u1eeb m\u00f4i tr\u01b0\u1eddng h\u1ec7 th\u1ed1ng c\u0169 ph\u00e2n m\u1ea3nh, d\u1ef1a tr\u00ean t\u1ec7p ph\u1eb3ng sang c\u01a1 s\u1edf d\u1eef li\u1ec7u quan h\u1ec7 m\u1ea1nh m\u1ebd m\u00e0 kh\u00f4ng l\u00e0m m\u1ea5t t\u00ednh ch\u00ednh x\u00e1c c\u1ee7a d\u1eef li\u1ec7u hay t\u1ea1o ra s\u1ef1 kh\u00f4ng nh\u1ea5t qu\u00e1n m\u1edbi. Gi\u1ea3i ph\u00e1p kh\u00f4ng n\u1eb1m \u1edf c\u00f4ng c\u1ee5 di d\u1eddi b\u1ea3n th\u00e2n, m\u00e0 n\u1eb1m \u1edf vi\u1ec7c m\u00f4 h\u00ecnh h\u00f3a tr\u1ef1c quan v\u00e0 c\u1ea5u tr\u00fac h\u00f3a logic d\u1eef li\u1ec7u tr\u01b0\u1edbc khi di chuy\u1ec3n b\u1ea5t k\u1ef3 byte d\u1eef li\u1ec7u n\u00e0o. Ch\u00fang t\u00f4i s\u1ebd kh\u00e1m ph\u00e1 ph\u01b0\u01a1ng ph\u00e1p ti\u1ebfp c\u1eadn, nh\u1eefng th\u00e1ch th\u1ee9c c\u1ee5 th\u1ec3 v\u1ec1 chu\u1ea9n h\u00f3a \u0111\u00e3 g\u1eb7p ph\u1ea3i, v\u00e0 k\u1ebft qu\u1ea3 c\u1ee5 th\u1ec3 t\u1eeb m\u1ed9t c\u00e1ch ti\u1ebfp c\u1eadn k\u1ef7 lu\u1eadt trong thi\u1ebft k\u1ebf l\u01b0\u1ee3c \u0111\u1ed3.<\/p>\n

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\"Marker-style<\/figure>\n<\/div>\n

\ud83d\udd0d Th\u00e1ch th\u1ee9c c\u1ee7a c\u00e1c c\u1ea5u tr\u00fac d\u1eef li\u1ec7u c\u0169<\/h2>\n

C\u00e1c h\u1ec7 th\u1ed1ng c\u0169 th\u01b0\u1eddng t\u00edch l\u0169y n\u1ee3 d\u1eef li\u1ec7u trong nhi\u1ec1u th\u1eadp k\u1ef7. Ch\u00fang \u0111\u01b0\u1ee3c x\u00e2y d\u1ef1ng \u0111\u1ec3 \u0111\u00e1p \u1ee9ng nhu c\u1ea7u c\u1ee5 th\u1ec3 c\u1ee7a th\u1eddi \u0111i\u1ec3m \u0111\u00f3, \u01b0u ti\u00ean t\u1ed1c \u0111\u1ed9 ph\u00e1t tri\u1ec3n h\u01a1n l\u00e0 kh\u1ea3 n\u0103ng duy tr\u00ec l\u00e2u d\u00e0i. Trong t\u00ecnh hu\u1ed1ng \u0111\u01b0\u1ee3c ph\u00e2n t\u00edch \u1edf \u0111\u00e2y, h\u1ec7 th\u1ed1ng ngu\u1ed3n s\u1eed d\u1ee5ng k\u1ebft h\u1ee3p gi\u1eefa c\u00e1c c\u1ea5u tr\u00fac ph\u00e2n c\u1ea5p v\u00e0 t\u1ec7p ph\u1eb3ng, \u0111\u00e3 \u0111\u01b0\u1ee3c s\u1eeda ch\u1eefa v\u00e0 gh\u00e9p n\u1ed1i qua nhi\u1ec1u n\u0103m c\u1eadp nh\u1eadt t\u1eebng b\u01b0\u1edbc.<\/p>\n

Nh\u1eefng \u0111\u1eb7c \u0111i\u1ec3m ch\u00ednh c\u1ee7a tr\u1ea1ng th\u00e1i c\u0169 bao g\u1ed3m:<\/p>\n

    \n
  • Logic \u0111\u01b0\u1ee3c ghi c\u1ee9ng:<\/strong>C\u00e1c quy t\u1eafc kinh doanh \u0111\u01b0\u1ee3c nh\u00fang tr\u1ef1c ti\u1ebfp trong m\u00e3 \u1ee9ng d\u1ee5ng thay v\u00ec \u0111\u01b0\u1ee3c th\u1ef1c thi \u1edf c\u1ea5p \u0111\u1ed9 c\u01a1 s\u1edf d\u1eef li\u1ec7u.<\/li>\n
  • L\u01b0u tr\u1eef kh\u00f4ng chu\u1ea9n h\u00f3a:<\/strong>\u0110\u1ec3 c\u1ea3i thi\u1ec7n hi\u1ec7u su\u1ea5t \u0111\u1ecdc trong b\u1ed1i c\u1ea3nh thi\u1ebfu ch\u1ec9 m\u1ee5c hi\u1ec7n \u0111\u1ea1i, d\u1eef li\u1ec7u th\u01b0\u1eddng b\u1ecb tr\u00f9ng l\u1eb7p tr\u00ean nhi\u1ec1u b\u1ea3ng kh\u00e1c nhau.<\/li>\n
  • Thi\u1ebfu t\u00ednh to\u00e0n v\u1eb9n tham chi\u1ebfu:<\/strong>C\u00e1c r\u00e0ng bu\u1ed9c kh\u00f3a ngo\u1ea1i hi\u1ebfm khi \u0111\u01b0\u1ee3c th\u1ef1c thi, cho ph\u00e9p c\u00e1c b\u1ea3n ghi b\u1ecb t\u00e1ch r\u1eddi lan r\u1ed9ng.<\/li>\n
  • Quy \u01b0\u1edbc \u0111\u1eb7t t\u00ean kh\u00f4ng nh\u1ea5t qu\u00e1n:<\/strong>C\u00e1c \u0111\u1ecbnh danh thay \u0111\u1ed5i r\u1ea5t l\u1edbn, khi\u1ebfn vi\u1ec7c \u00e1nh x\u1ea1 t\u1ef1 \u0111\u1ed9ng g\u1ea7n nh\u01b0 kh\u00f4ng th\u1ec3 th\u1ef1c hi\u1ec7n \u0111\u01b0\u1ee3c m\u00e0 kh\u00f4ng c\u1ea7n can thi\u1ec7p th\u1ee7 c\u00f4ng.<\/li>\n<\/ul>\n

    M\u00f4i tr\u01b0\u1eddng n\u00e0y t\u1ea1o ra nguy c\u01a1 cao v\u1ec1s\u1ef1 b\u1ea5t th\u01b0\u1eddng khi c\u1eadp nh\u1eadt<\/strong>. N\u1ebfu \u0111\u1ecba ch\u1ec9 kh\u00e1ch h\u00e0ng thay \u0111\u1ed5i, n\u00f3 ph\u1ea3i \u0111\u01b0\u1ee3c c\u1eadp nh\u1eadt tr\u00ean h\u00e0ng ch\u1ee5c b\u1ea3ng kh\u00e1c nhau. Vi\u1ec7c kh\u00f4ng c\u1eadp nh\u1eadt m\u1ecdi tr\u01b0\u1eddng h\u1ee3p d\u1eabn \u0111\u1ebfn s\u1ef1 kh\u00f4ng nh\u1ea5t qu\u00e1n d\u1eef li\u1ec7u. H\u01a1n n\u1eefa, s\u1ef1 b\u1ea5t th\u01b0\u1eddng khi ch\u00e8n d\u1eef li\u1ec7u<\/strong> ng\u0103n c\u1ea3n vi\u1ec7c th\u00eam d\u1eef li\u1ec7u m\u1edbi m\u00e0 kh\u00f4ng c\u1ea7n sao ch\u00e9p c\u00e1c b\u1ea3n ghi hi\u1ec7n c\u00f3, v\u00e0 s\u1ef1 b\u1ea5t th\u01b0\u1eddng khi x\u00f3a d\u1eef li\u1ec7u<\/strong>\u0111e d\u1ecda m\u1ea5t th\u00f4ng tin quan tr\u1ecdng khi c\u00e1c b\u1ea3n ghi kh\u00f4ng li\u00ean quan b\u1ecb x\u00f3a.<\/p>\n

    \ud83d\udee0\ufe0f Vai tr\u00f2 c\u1ee7a s\u01a1 \u0111\u1ed3 quan h\u1ec7 th\u1ef1c th\u1ec3<\/h2>\n

    S\u01a1 \u0111\u1ed3 quan h\u1ec7 th\u1ef1c th\u1ec3 kh\u00f4ng ch\u1ec9 \u0111\u01a1n thu\u1ea7n l\u00e0 m\u1ed9t b\u1ea3n v\u1ebd; \u0111\u00f3 l\u00e0 m\u1ed9t h\u1ee3p \u0111\u1ed3ng logic gi\u1eefa d\u1eef li\u1ec7u v\u00e0 c\u00e1c \u1ee9ng d\u1ee5ng ti\u00eau th\u1ee5 n\u00f3. Trong qu\u00e1 tr\u00ecnh di d\u1eddi n\u00e0y, ERD \u0111\u00f3ng vai tr\u00f2 l\u00e0 ngu\u1ed3n th\u00f4ng tin duy nh\u1ea5t. N\u00f3 bu\u1ed9c \u0111\u1ed9i ng\u0169 ph\u1ea3i x\u00e1c \u0111\u1ecbnh r\u00f5 r\u00e0ng c\u00e1c m\u1ed1i quan h\u1ec7, x\u00e1c \u0111\u1ecbnh kh\u00f3a ch\u00ednh v\u00e0 thi\u1ebft l\u1eadp c\u00e1c quy t\u1eafc b\u1ed9i s\u1ed1 tr\u01b0\u1edbc khi tri\u1ec3n khai v\u1eadt l\u00fd b\u1eaft \u0111\u1ea7u.<\/p>\n

    T\u1ea1i sao ERD l\u1ea1i quan tr\u1ecdng \u0111\u1ed1i v\u1edbi d\u1ef1 \u00e1n c\u1ee5 th\u1ec3 n\u00e0y?<\/p>\n

      \n
    • Tr\u1ef1c quan h\u00f3a \u0111\u1ed9 ph\u1ee9c t\u1ea1p:<\/strong>C\u00e1c m\u1ed1i quan h\u1ec7 d\u1eef li\u1ec7u c\u0169 l\u00e0 m\u01a1 h\u1ed3. S\u01a1 \u0111\u1ed3 \u0111\u00e3 l\u00e0m r\u00f5 c\u00e1c m\u1ed1i ph\u1ee5 thu\u1ed9c \u1ea9n.<\/li>\n
    • Th\u1ef1c thi chu\u1ea9n h\u00f3a:<\/strong>M\u00f4 h\u00ecnh y\u00eau c\u1ea7u \u0111\u1ed9i ng\u0169 \u00e1p d\u1ee5ng c\u00e1c quy t\u1eafc chu\u1ea9n h\u00f3a \u0111\u1ec3 lo\u1ea1i b\u1ecf s\u1ef1 tr\u00f9ng l\u1eb7p m\u1ed9t c\u00e1ch h\u1ec7 th\u1ed1ng.<\/li>\n
    • H\u01b0\u1edbng d\u1eabn \u00e1nh x\u1ea1:<\/strong>N\u00f3 cung c\u1ea5p con \u0111\u01b0\u1eddng r\u00f5 r\u00e0ng \u0111\u1ec3 \u00e1nh x\u1ea1 c\u00e1c c\u1ed9t c\u0169 sang c\u00e1c b\u1ea3ng m\u1edbi \u0111\u00e3 \u0111\u01b0\u1ee3c chu\u1ea9n h\u00f3a.<\/li>\n
    • Giao ti\u1ebfp v\u1edbi c\u00e1c b\u00ean li\u00ean quan:<\/strong>N\u00f3 cho ph\u00e9p c\u00e1c nh\u00e0 ph\u00e2n t\u00edch kinh doanh x\u00e1c minh logic d\u1ef1a tr\u00ean c\u00e1c quy tr\u00ecnh kinh doanh th\u1ef1c t\u1ebf.<\/li>\n<\/ul>\n

      \ud83d\udcc2 T\u00ecnh hu\u1ed1ng nghi\u00ean c\u1ee9u \u0111i\u1ec3n h\u00ecnh: T\u00e1i c\u1ea5u tr\u00fac ng\u00e2n h\u00e0ng b\u00e1n l\u1ebb<\/h2>\n

      \u0110\u1ed1i v\u1edbi ph\u00e2n t\u00edch n\u00e0y, ch\u00fang t\u00f4i xem x\u00e9t m\u1ed9t t\u1ed5 ch\u1ee9c ng\u00e2n h\u00e0ng b\u00e1n l\u1ebb chuy\u1ec3n t\u1eeb h\u1ec7 th\u1ed1ng th\u1eddi k\u1ef3 mainframe sang c\u01a1 s\u1edf d\u1eef li\u1ec7u quan h\u1ec7 d\u1ef1a tr\u00ean \u0111\u00e1m m\u00e2y. H\u1ec7 th\u1ed1ng c\u0169 qu\u1ea3n l\u00fd t\u00e0i kho\u1ea3n kh\u00e1ch h\u00e0ng, giao d\u1ecbch v\u00e0 h\u1ed3 s\u01a1 vay v\u1ed1n. Tuy nhi\u00ean, do \u0111\u1ed9 tu\u1ed5i c\u1ee7a h\u1ec7 th\u1ed1ng, th\u00f4ng tin kh\u00e1ch h\u00e0ng \u0111\u00e3 \u0111\u01b0\u1ee3c l\u01b0u tr\u1eef tr\u00f9ng l\u1eb7p trong c\u00e1c nh\u1eadt k\u00fd giao d\u1ecbch.<\/p>\n

      Tr\u01b0\u1edbc khi ph\u00e2n t\u00edch s\u01a1 \u0111\u1ed3 ERD:<\/strong><\/p>\n\n\n\n\n\n\n\n
      T\u00ean b\u1ea3ng<\/th>\nKh\u00f3a ch\u00ednh<\/th>\nD\u1eef li\u1ec7u tr\u00f9ng l\u1eb7p<\/th>\nV\u1ea5n \u0111\u1ec1<\/th>\n<\/tr>\n<\/thead>\n
      TXN_LOG<\/strong><\/td>\nTXN_ID<\/td>\nT\u00ean kh\u00e1ch h\u00e0ng, \u0110\u1ecba ch\u1ec9<\/td>\nVi\u1ec7c thay \u0111\u1ed5i \u0111\u1ecba ch\u1ec9 \u0111\u00f2i h\u1ecfi c\u1eadp nh\u1eadt h\u00e0ng ngh\u00ecn h\u00e0ng.<\/td>\n<\/tr>\n
      ACCT_HIST<\/strong><\/td>\nHIST_ID<\/td>\nM\u00e3 chi nh\u00e1nh, \u0110\u1ecba \u0111i\u1ec3m chi nh\u00e1nh<\/td>\nVi\u1ec7c \u0111\u00f3ng c\u1eeda chi nh\u00e1nh d\u1eabn \u0111\u1ebfn xung \u0111\u1ed9t d\u1eef li\u1ec7u.<\/td>\n<\/tr>\n
      LOAN_DETL<\/strong><\/td>\nLOAN_ID<\/td>\nM\u00e3 kh\u00e1ch h\u00e0ng, M\u00e3 t\u00e0i kho\u1ea3n<\/td>\nC\u00e1c li\u00ean k\u1ebft th\u01b0\u1eddng b\u1ecb thi\u1ebfu ho\u1eb7c tr\u00f9ng l\u1eb7p.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

      C\u1ea5u tr\u00fac n\u00e0y vi ph\u1ea1m c\u00e1c nguy\u00ean t\u1eafc c\u01a1 b\u1ea3n c\u1ee7a thi\u1ebft k\u1ebf c\u01a1 s\u1edf d\u1eef li\u1ec7u. Quy tr\u00ecnh ERD \u0111\u00f2i h\u1ecfi ph\u1ea3i chia nh\u1ecf c\u00e1c b\u1ea3ng n\u00e0y th\u00e0nh c\u00e1c th\u1ef1c th\u1ec3 nguy\u00ean t\u1eed, \u0111\u1ed9c l\u1eadp.<\/p>\n

      \ud83e\udde9 B\u01b0\u1edbc 1: X\u00e1c \u0111\u1ecbnh c\u00e1c th\u1ef1c th\u1ec3 v\u00e0 m\u1ed1i quan h\u1ec7<\/h2>\n

      Giai \u0111o\u1ea1n \u0111\u1ea7u ti\u00ean c\u1ee7a qu\u00e1 tr\u00ecnh di chuy\u1ec3n bao g\u1ed3m vi\u1ec7c tr\u00edch xu\u1ea5t m\u1ecdi b\u1ea3ng v\u00e0 c\u1ed9t t\u1eeb h\u1ec7 th\u1ed1ng c\u0169. Sau \u0111\u00f3, nh\u00f3m \u0111\u00e3 \u00e1nh x\u1ea1 ch\u00fang th\u00e0nh c\u00e1c th\u1ef1c th\u1ec3 logic. M\u1ee5c ti\u00eau l\u00e0 x\u00e1c \u0111\u1ecbnh c\u00e1c \u0111\u1ed1i t\u01b0\u1ee3ng ri\u00eang bi\u1ec7t trong l\u0129nh v\u1ef1c kinh doanh.<\/p>\n

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      • Kh\u00e1ch h\u00e0ng:<\/strong> M\u1ed9t c\u00e1 nh\u00e2n ho\u1eb7c th\u1ef1c th\u1ec3 duy nh\u1ea5t s\u1edf h\u1eefu m\u1ed9t t\u00e0i kho\u1ea3n.<\/li>\n
      • T\u00e0i kho\u1ea3n:<\/strong> M\u1ed9t s\u1ea3n ph\u1ea9m t\u00e0i ch\u00ednh c\u1ee5 th\u1ec3 do kh\u00e1ch h\u00e0ng s\u1edf h\u1eefu.<\/li>\n
      • Giao d\u1ecbch:<\/strong> M\u1ed9t chuy\u1ec3n \u0111\u1ed9ng ti\u1ec1n t\u1ec7 li\u00ean quan \u0111\u1ebfn m\u1ed9t t\u00e0i kho\u1ea3n.<\/li>\n
      • Chi nh\u00e1nh:<\/strong> M\u1ed9t \u0111\u1ecba \u0111i\u1ec3m v\u1eadt l\u00fd n\u01a1i c\u00e1c ho\u1ea1t \u0111\u1ed9ng ng\u00e2n h\u00e0ng di\u1ec5n ra.<\/li>\n<\/ul>\n

        Sau khi c\u00e1c th\u1ef1c th\u1ec3 \u0111\u01b0\u1ee3c x\u00e1c \u0111\u1ecbnh, c\u00e1c m\u1ed1i quan h\u1ec7 \u0111\u00e3 \u0111\u01b0\u1ee3c thi\u1ebft l\u1eadp. S\u01a1 \u0111\u1ed3 ERD cho th\u1ea5y m\u1ed9t Kh\u00e1ch h\u00e0ng duy nh\u1ea5t c\u00f3 th\u1ec3 s\u1edf h\u1eefu nhi\u1ec1u T\u00e0i kho\u1ea3n. M\u1ed9t T\u00e0i kho\u1ea3n c\u00f3 th\u1ec3 c\u00f3 nhi\u1ec1u Giao d\u1ecbch. M\u1ed9t Giao d\u1ecbch \u0111\u01b0\u1ee3c li\u00ean k\u1ebft v\u1edbi m\u1ed9t Chi nh\u00e1nh c\u1ee5 th\u1ec3. C\u00e1c m\u1ed1i quan h\u1ec7 n\u00e0y th\u01b0\u1eddng \u0111\u01b0\u1ee3c bi\u1ec3u di\u1ec5n nh\u01b0 sau:<\/p>\n

          \n
        • M\u1ed9t-\u0111\u1ebfn-Nhi\u1ec1u (1:N):<\/strong> M\u1ed9t Kh\u00e1ch h\u00e0ng \u0111\u1ebfn Nhi\u1ec1u T\u00e0i kho\u1ea3n.<\/li>\n
        • M\u1ed9t-\u0111\u1ebfn-Nhi\u1ec1u (1:N):<\/strong> M\u1ed9t T\u00e0i kho\u1ea3n \u0111\u1ebfn Nhi\u1ec1u Giao d\u1ecbch.<\/li>\n
        • Nhi\u1ec1u-\u0111\u1ebfn-M\u1ed9t (M:1):<\/strong> Nhi\u1ec1u Giao d\u1ecbch \u0111\u1ebfn M\u1ed9t Chi nh\u00e1nh.<\/li>\n<\/ul>\n

          B\u1eb1ng c\u00e1ch tr\u1ef1c quan h\u00f3a c\u00e1c k\u1ebft n\u1ed1i n\u00e0y, \u0111\u1ed9i ng\u0169 \u0111\u00e3 x\u00e1c \u0111\u1ecbnh \u0111\u01b0\u1ee3c n\u01a1i d\u1eef li\u1ec7u \u0111ang b\u1ecb tr\u00f9ng l\u1eb7p. V\u00ed d\u1ee5, T\u00ean Kh\u00e1ch h\u00e0ng xu\u1ea5t hi\u1ec7n trong b\u1ea3ngTXN_LOG<\/code> b\u1ea3ng. Trong m\u00f4 h\u00ecnh chu\u1ea9n h\u00f3a, b\u1ea3ng giao d\u1ecbch ch\u1ec9 n\u00ean l\u01b0u m\u1ed9t tham chi\u1ebfu (kh\u00f3a ngo\u1ea1i) \u0111\u1ebfn b\u1ea3ng Kh\u00e1ch h\u00e0ng, ch\u1ee9 kh\u00f4ng ph\u1ea3i d\u1eef li\u1ec7u b\u1ea3n th\u00e2n.<\/p>\n

          \ud83d\udcd0 B\u01b0\u1edbc 2: \u00c1p d\u1ee5ng c\u00e1c quy t\u1eafc chu\u1ea9n h\u00f3a<\/h2>\n

          Chu\u1ea9n h\u00f3a l\u00e0 qu\u00e1 tr\u00ecnh t\u1ed5 ch\u1ee9c d\u1eef li\u1ec7u nh\u1eb1m gi\u1ea3m thi\u1ec3u s\u1ef1 tr\u00f9ng l\u1eb7p v\u00e0 c\u1ea3i thi\u1ec7n t\u00ednh to\u00e0n v\u1eb9n. M\u00f4 h\u00ecnh ERD \u0111\u00e3 d\u1eabn d\u1eaft \u0111\u1ed9i ng\u0169 \u0111i qua c\u00e1c d\u1ea1ng chu\u1ea9n h\u00f3a ti\u00eau chu\u1ea9n.<\/p>\n

          D\u1ea1ng chu\u1ea9n h\u00f3a th\u1ee9 nh\u1ea5t (1NF)<\/h3>\n

          H\u1ec7 th\u1ed1ng c\u0169 ch\u1ee9a c\u00e1c nh\u00f3m l\u1eb7p l\u1ea1i. V\u00ed d\u1ee5, m\u1ed9t h\u00e0ng duy nh\u1ea5t trong b\u1ea3ng kh\u00e1ch h\u00e0ng c\u0169 c\u00f3 th\u1ec3 l\u01b0u nhi\u1ec1u s\u1ed1 \u0111i\u1ec7n tho\u1ea1i trong m\u1ed9t c\u1ed9t duy nh\u1ea5t (v\u00ed d\u1ee5: \u201c555-0199, 555-0200\u201d).<\/p>\n

            \n
          • V\u1ea5n \u0111\u1ec1:<\/strong> \u0110i\u1ec1u n\u00e0y khi\u1ebfn vi\u1ec7c truy v\u1ea5n m\u1ed9t s\u1ed1 \u0111i\u1ec7n tho\u1ea1i c\u1ee5 th\u1ec3 tr\u1edf n\u00ean kh\u00f3 kh\u0103n v\u00e0 vi ph\u1ea1m t\u00ednh nguy\u00ean t\u1eed.<\/li>\n
          • Gi\u1ea3i ph\u00e1p ERD:<\/strong> T\u1ea1o m\u1ed9t th\u1ef1c th\u1ec3 ri\u00eang bi\u1ec7t l\u00e0Contact_Information<\/strong> li\u00ean k\u1ebft v\u1edbi th\u1ef1c th\u1ec3 Kh\u00e1ch h\u00e0ng. M\u1ed7i h\u00e0ng trong b\u1ea3ng m\u1edbi n\u00e0y l\u01b0u \u0111\u00fang m\u1ed9t s\u1ed1 \u0111i\u1ec7n tho\u1ea1i.<\/li>\n<\/ul>\n

            D\u1ea1ng chu\u1ea9n h\u00f3a th\u1ee9 hai (2NF)<\/h3>\n

            2NF y\u00eau c\u1ea7u b\u1ea3ng ph\u1ea3i \u1edf d\u1ea1ng 1NF v\u00e0 t\u1ea5t c\u1ea3 c\u00e1c thu\u1ed9c t\u00ednh kh\u00f4ng kh\u00f3a ph\u1ea3i ph\u1ee5 thu\u1ed9c ho\u00e0n to\u00e0n v\u00e0o kh\u00f3a ch\u00ednh. B\u1ea3ng TXN_LOG<\/code> c\u00f3 kh\u00f3a h\u1ee3p th\u00e0nh l\u00e0TXN_ID<\/code> v\u00e0DATE<\/code>. Tuy nhi\u00ean, chi ti\u1ebft kh\u00e1ch h\u00e0ng ch\u1ec9 ph\u1ee5 thu\u1ed9c v\u00e0oM\u00e3 kh\u00e1ch h\u00e0ng<\/code>, kh\u00f4ng ph\u1ea3i ng\u00e0y giao d\u1ecbch.<\/p>\n

              \n
            • V\u1ea5n \u0111\u1ec1:<\/strong>D\u1eef li\u1ec7u kh\u00e1ch h\u00e0ng b\u1ecb l\u1eb7p l\u1ea1i cho m\u1ed7i giao d\u1ecbch, g\u00e2y ra c\u00e1c b\u1ea5t th\u01b0\u1eddng khi c\u1eadp nh\u1eadt.<\/li>\n
            • Gi\u1ea3i ph\u00e1p ERD:<\/strong> Lo\u1ea1i b\u1ecf chi ti\u1ebft kh\u00e1ch h\u00e0ng kh\u1ecfi b\u1ea3ng giao d\u1ecbch. L\u01b0u tr\u1eef ch\u00fang trong m\u1ed9t b\u1ea3ng chuy\u00ean d\u1ee5ng Kh\u00e1ch h\u00e0ng<\/strong> b\u1ea3ng v\u00e0 li\u00ean k\u1ebft ch\u00fang th\u00f4ng qua kh\u00f3a ngo\u1ea1i.<\/li>\n<\/ul>\n

              D\u1ea1ng chu\u1ea9n h\u00f3a th\u1ee9 ba (3NF)<\/h3>\n

              3NF y\u00eau c\u1ea7u t\u1ea5t c\u1ea3 c\u00e1c thu\u1ed9c t\u00ednh ch\u1ec9 ph\u1ee5 thu\u1ed9c v\u00e0o kh\u00f3a ch\u00ednh, kh\u00f4ng c\u00f3 ph\u1ee5 thu\u1ed9c b\u1eafc c\u1ea7u. Trong h\u1ec7 th\u1ed1ng c\u0169, t\u00ean v\u00e0 \u0111\u1ecba ch\u1ec9 Chi nh\u00e1nh<\/code> \u0111\u01b0\u1ee3c l\u01b0u tr\u1eef trong b\u1ea3ng T\u00e0i kho\u1ea3n<\/code> b\u1ea3ng, nh\u01b0ng ch\u00fang ph\u1ee5 thu\u1ed9c v\u00e0o M\u00e3 chi nh\u00e1nh<\/code>, kh\u00f4ng ph\u1ea3i M\u00e3 t\u00e0i kho\u1ea3n<\/code>.<\/p>\n

                \n
              • V\u1ea5n \u0111\u1ec1:<\/strong> N\u1ebfu m\u1ed9t chi nh\u00e1nh chuy\u1ec3n \u0111\u1ecba \u0111i\u1ec3m, m\u1ecdi b\u1ea3n ghi t\u00e0i kho\u1ea3n li\u00ean quan \u0111\u1ebfn chi nh\u00e1nh \u0111\u00f3 \u0111\u1ec1u c\u1ea7n \u0111\u01b0\u1ee3c c\u1eadp nh\u1eadt.<\/li>\n
              • Gi\u1ea3i ph\u00e1p ERD:<\/strong> T\u1ea1o m\u1ed9t b\u1ea3ng \u0111\u1ed9c l\u1eadp Chi nh\u00e1nh<\/strong> b\u1ea3ng. B\u1ea3ng T\u00e0i kho\u1ea3n<\/code> hi\u1ec7n ch\u1ec9 l\u01b0u m\u00e3 M\u00e3 chi nh\u00e1nh<\/code>.<\/li>\n<\/ul>\n

                \ud83d\udd04 B\u01b0\u1edbc 3: Chi\u1ebfn l\u01b0\u1ee3c th\u1ef1c hi\u1ec7n di chuy\u1ec3n<\/h2>\n

                V\u1edbi ERD m\u1edbi \u0111\u01b0\u1ee3c x\u00e1c \u0111\u1ecbnh, k\u1ebf ho\u1ea1ch di chuy\u1ec3n \u0111\u00e3 \u0111\u01b0\u1ee3c x\u00e2y d\u1ef1ng d\u1ef1a tr\u00ean l\u01b0\u1ee3c \u0111\u1ed3 m\u1edbi. Qu\u00e1 tr\u00ecnh n\u00e0y kh\u00f4ng \u0111\u01a1n thu\u1ea7n l\u00e0 sao ch\u00e9p v\u00e0 d\u00e1n; \u0111\u00f3 l\u00e0 m\u1ed9t qu\u00e1 tr\u00ecnh chuy\u1ec3n \u0111\u1ed5i.<\/p>\n

                  \n
                1. Tr\u00edch xu\u1ea5t d\u1eef li\u1ec7u:<\/strong>D\u1eef li\u1ec7u th\u00f4 \u0111\u00e3 \u0111\u01b0\u1ee3c tr\u00edch xu\u1ea5t t\u1eeb c\u00e1c h\u1ec7 th\u1ed1ng ngu\u1ed3n c\u0169 v\u00e0o khu v\u1ef1c t\u1ea1m th\u1eddi.<\/li>\n
                2. L\u00e0m s\u1ea1ch:<\/strong>C\u00e1c b\u1ea3n ghi tr\u00f9ng l\u1eb7p \u0111\u00e3 \u0111\u01b0\u1ee3c x\u00e1c \u0111\u1ecbnh v\u00e0 g\u1ed9p l\u1ea1i d\u1ef1a tr\u00ean c\u00e1c kh\u00f3a kinh doanh \u0111\u01b0\u1ee3c \u0111\u1ecbnh ngh\u0129a trong s\u01a1 \u0111\u1ed3 ERD.<\/li>\n
                3. Chuy\u1ec3n \u0111\u1ed5i:<\/strong>C\u00e1c t\u1eadp l\u1ec7nh \u0111\u00e3 \u0111\u01b0\u1ee3c vi\u1ebft \u0111\u1ec3 chia c\u00e1c c\u1ed9t kh\u00f4ng chu\u1ea9n h\u00f3a th\u00e0nh c\u00e1c b\u1ea3ng m\u1edbi theo c\u00e1c quy t\u1eafc 1NF, 2NF v\u00e0 3NF.<\/li>\n
                4. \u00c1nh x\u1ea1:<\/strong>C\u00e1c kh\u00f3a ngo\u1ea1i \u0111\u00e3 \u0111\u01b0\u1ee3c t\u1ea1o \u0111\u1ec3 li\u00ean k\u1ebft c\u00e1c b\u1ea3ng m\u1edbi. C\u00e1c kh\u00f3a thay th\u1ebf (ID do h\u1ec7 th\u1ed1ng t\u1ea1o) \u0111\u00e3 \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng \u0111\u1ec3 \u0111\u1ea3m b\u1ea3o \u0111\u1ed9 \u1ed5n \u0111\u1ecbnh \u0111\u1ed9c l\u1eadp v\u1edbi c\u00e1c kh\u00f3a kinh doanh c\u0169.<\/li>\n
                5. T\u1ea3i d\u1eef li\u1ec7u:<\/strong>D\u1eef li\u1ec7u \u0111\u00e3 \u0111\u01b0\u1ee3c ch\u00e8n v\u00e0o c\u01a1 s\u1edf d\u1eef li\u1ec7u \u0111\u00edch theo th\u1ee9 t\u1ef1 c\u1ee5 th\u1ec3 \u0111\u1ec3 tu\u00e2n th\u1ee7 t\u00ednh to\u00e0n v\u1eb9n tham chi\u1ebfu (cha tr\u01b0\u1edbc con).<\/li>\n<\/ol>\n

                  S\u01a1 \u0111\u1ed3 ERD l\u00e0 r\u1ea5t quan tr\u1ecdng \u1edf \u0111\u00e2y. N\u00f3 x\u00e1c \u0111\u1ecbnh th\u1ee9 t\u1ef1 t\u1ea3i. V\u00ed d\u1ee5, b\u1ea3ng Kh\u00e1ch h\u00e0ng<\/strong> ph\u1ea3i \u0111\u01b0\u1ee3c \u0111i\u1ec1n tr\u01b0\u1edbc b\u1ea3ng T\u00e0i kho\u1ea3n<\/strong>, b\u1ea3ng n\u00e0y ph\u1ea3i \u0111\u01b0\u1ee3c \u0111i\u1ec1n tr\u01b0\u1edbc b\u1ea3ng Giao d\u1ecbch<\/strong> b\u1ea3ng. Th\u1eed t\u1ea3i theo th\u1ee9 t\u1ef1 kh\u00e1c s\u1ebd d\u1eabn \u0111\u1ebfn vi ph\u1ea1m r\u00e0ng bu\u1ed9c.<\/p>\n

                  \u2705 B\u01b0\u1edbc 4: X\u00e1c minh v\u00e0 Ki\u1ec3m th\u1eed<\/h2>\n

                  Vi\u1ec7c x\u00e1c minh sau di chuy\u1ec3n l\u00e0 r\u1ea5t k\u1ef9 l\u01b0\u1ee1ng. M\u1ee5c ti\u00eau l\u00e0 \u0111\u1ea3m b\u1ea3o t\u1ed5ng l\u01b0\u1ee3ng d\u1eef li\u1ec7u v\u1eabn gi\u1eef nguy\u00ean, d\u00f9 c\u1ea5u tr\u00fac \u0111\u00e3 thay \u0111\u1ed5i. \u0110\u1ed9i ng\u0169 \u0111\u00e3 s\u1eed d\u1ee5ng s\u01a1 \u0111\u1ed3 ERD \u0111\u1ec3 x\u00e1c \u0111\u1ecbnh tr\u1ea1ng th\u00e1i d\u1eef li\u1ec7u mong \u0111\u1ee3i.<\/p>\n

                  Ki\u1ec3m tra t\u00ednh to\u00e0n v\u1eb9n<\/h3>\n
                    \n
                  • To\u00e0n v\u1eb9n tham chi\u1ebfu:<\/strong> \u0110\u1ea3m b\u1ea3o m\u1ed7i Customer_ID<\/code> trong b\u1ea3ng T\u00e0i kho\u1ea3n t\u1ed3n t\u1ea1i trong b\u1ea3ng Kh\u00e1ch h\u00e0ng.<\/li>\n
                  • \u0110\u1ea7y \u0111\u1ee7:<\/strong>X\u00e1c minh r\u1eb1ng kh\u00f4ng c\u00f3 b\u1ea3n ghi n\u00e0o b\u1ecb m\u1ea5t trong qu\u00e1 tr\u00ecnh chuy\u1ec3n \u0111\u1ed5i.<\/li>\n
                  • \u0110\u1ed9c nh\u1ea5t:<\/strong>X\u00e1c nh\u1eadn r\u1eb1ng c\u00e1c kh\u00f3a ch\u00ednh l\u00e0 duy nh\u1ea5t v\u00e0 kh\u00f4ng c\u00f3 b\u1ea3n ghi tr\u00f9ng l\u1eb7p n\u00e0o t\u1ed3n t\u1ea1i trong c\u00e1c b\u1ea3ng m\u1edbi.<\/li>\n<\/ul>\n

                    C\u00e1c ch\u1ec9 s\u1ed1 so s\u00e1nh<\/h3>\n

                    C\u00e1c ch\u1ec9 s\u1ed1 sau \u0111\u00e2y \u0111\u00e3 \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng \u0111\u1ec3 so s\u00e1nh h\u1ec7 th\u1ed1ng ngu\u1ed3n v\u00e0 h\u1ec7 th\u1ed1ng \u0111\u00edch:<\/p>\n\n\n\n\n\n\n\n\n
                    Ch\u1ec9 s\u1ed1 x\u00e1c th\u1ef1c<\/th>\nTi\u00eau chu\u1ea9n m\u1ee5c ti\u00eau<\/th>\nPh\u01b0\u01a1ng ph\u00e1p<\/th>\n<\/tr>\n<\/thead>\n
                    S\u1ed1 l\u01b0\u1ee3ng b\u1ea3n ghi<\/strong><\/td>\nS\u1ed1 l\u01b0\u1ee3ng ngu\u1ed3n = S\u1ed1 l\u01b0\u1ee3ng m\u1ee5c ti\u00eau<\/td>\nS\u1ed1 l\u01b0\u1ee3ng h\u00e0ng theo t\u1eebng th\u1ef1c th\u1ec3 \u0111\u00e3 chu\u1ea9n h\u00f3a<\/td>\n<\/tr>\n
                    T\u1ed5ng gi\u00e1 tr\u1ecb<\/strong><\/td>\nT\u1ed5ng s\u1ed1 d\u01b0 ngu\u1ed3n = T\u1ed5ng s\u1ed1 d\u01b0 m\u1ee5c ti\u00eau<\/td>\nT\u1ed5ng h\u1ee3p c\u00e1c tr\u01b0\u1eddng s\u1ed1 h\u1ecdc<\/td>\n<\/tr>\n
                    Ki\u1ec3m tra gi\u00e1 tr\u1ecb r\u1ed7ng<\/strong><\/td>\nKh\u00f4ng c\u00f3 gi\u00e1 tr\u1ecb NULL kh\u00f4ng mong mu\u1ed1n trong c\u00e1c c\u1ed9t KH\u00d4NG \u0110\u01af\u1ee2C R\u1ed6NG<\/td>\nGi\u1edbi h\u1ea1n truy v\u1ea5n<\/td>\n<\/tr>\n
                    Ki\u1ec3m tra b\u1ea3n ghi tr\u00f9ng l\u1eb7p<\/strong><\/td>\nKh\u00f4ng c\u00f3 b\u1ea3n ghi tr\u00f9ng l\u1eb7p tr\u00ean Kh\u00f3a ch\u00ednh<\/td>\nPh\u00e2n t\u00edch GROUP BY<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

                    \ud83d\udcc9 T\u00e1c \u0111\u1ed9ng c\u1ee7a vi\u1ec7c gi\u1ea3m thi\u1ec3u d\u01b0 th\u1eeba<\/h2>\n

                    S\u1ef1 chuy\u1ec3n \u0111\u1ed5i t\u1eeb c\u1ea5u tr\u00fac c\u0169 sang m\u00f4 h\u00ecnh ERD \u0111\u00e3 chu\u1ea9n h\u00f3a mang l\u1ea1i nh\u1eefng c\u1ea3i thi\u1ec7n r\u00f5 r\u1ec7t v\u1ec1 hi\u1ec7u su\u1ea5t v\u00e0 b\u1ea3o tr\u00ec.<\/p>\n

                      \n
                    • Hi\u1ec7u qu\u1ea3 l\u01b0u tr\u1eef:<\/strong> B\u1eb1ng c\u00e1ch lo\u1ea1i b\u1ecf c\u00e1c \u0111\u1ecba ch\u1ec9 kh\u00e1ch h\u00e0ng v\u00e0 chi ti\u1ebft chi nh\u00e1nh tr\u00f9ng l\u1eb7p, nhu c\u1ea7u l\u01b0u tr\u1eef gi\u1ea3m kho\u1ea3ng 35%.<\/li>\n
                    • Hi\u1ec7u su\u1ea5t truy v\u1ea5n:<\/strong> C\u00e1c truy v\u1ea5n tr\u01b0\u1edbc \u0111\u00e2y c\u1ea7n qu\u00e9t c\u00e1c b\u1ea3ng l\u1edbn, kh\u00f4ng chu\u1ea9n h\u00f3a nay tr\u1edf n\u00ean nhanh h\u01a1n nh\u1edd k\u1ebft h\u1ee3p c\u00e1c b\u1ea3ng nh\u1ecf, \u0111\u01b0\u1ee3c ch\u1ec9 m\u1ee5c.<\/li>\n
                    • T\u1ed1c \u0111\u1ed9 c\u1eadp nh\u1eadt:<\/strong> C\u1eadp nh\u1eadt \u0111\u1ecba ch\u1ec9 kh\u00e1ch h\u00e0ng hi\u1ec7n nay ch\u1ec9 c\u1ea7n c\u1eadp nh\u1eadt m\u1ed9t h\u00e0ng duy nh\u1ea5t trong b\u1ea3ng Kh\u00e1ch h\u00e0ng<\/strong> b\u1ea3ng, thay v\u00ec h\u00e0ng ng\u00e0n thao t\u00e1c c\u1eadp nh\u1eadt tr\u00ean c\u00e1c nh\u1eadt k\u00fd giao d\u1ecbch.<\/li>\n
                    • T\u00ednh nh\u1ea5t qu\u00e1n d\u1eef li\u1ec7u:<\/strong> Nguy c\u01a1 d\u1eef li\u1ec7u m\u00e2u thu\u1eabn (v\u00ed d\u1ee5: hai \u0111\u1ecba ch\u1ec9 kh\u00e1c nhau cho c\u00f9ng m\u1ed9t kh\u00e1ch h\u00e0ng) \u0111\u00e3 \u0111\u01b0\u1ee3c lo\u1ea1i b\u1ecf nh\u1edd \u0111\u1ea3m b\u1ea3o ngu\u1ed3n d\u1eef li\u1ec7u duy nh\u1ea5t.<\/li>\n<\/ul>\n

                      \ud83d\udee1\ufe0f X\u1eed l\u00fd c\u00e1c tr\u01b0\u1eddng h\u1ee3p \u0111\u1eb7c bi\u1ec7t v\u00e0 d\u1eef li\u1ec7u l\u1ecbch s\u1eed<\/h2>\n

                      M\u1ed9t trong nh\u1eefng kh\u00eda c\u1ea1nh kh\u00f3 kh\u0103n nh\u1ea5t c\u1ee7a vi\u1ec7c di d\u1eddi h\u1ec7 th\u1ed1ng c\u0169 l\u00e0 x\u1eed l\u00fd d\u1eef li\u1ec7u l\u1ecbch s\u1eed kh\u00f4ng ph\u00f9 h\u1ee3p v\u1edbi m\u00f4 h\u00ecnh m\u1edbi. ERD \u0111\u00e3 gi\u00fap x\u00e1c \u0111\u1ecbnh c\u00e1ch x\u1eed l\u00fd nh\u1eefng ngo\u1ea1i l\u1ec7 n\u00e0y m\u1ed9t c\u00e1ch tr\u01a1n tru.<\/p>\n

                        \n
                      • C\u00e1c b\u1ea3n ghi b\u1ecb b\u1ecf r\u01a1i:<\/strong> C\u00e1c giao d\u1ecbch li\u00ean k\u1ebft v\u1edbi kh\u00e1ch h\u00e0ng kh\u00f4ng c\u00f2n t\u1ed3n t\u1ea1i trong ngu\u1ed3n \u0111\u00e3 b\u1ecb \u0111\u00e1nh d\u1ea5u. \u0110\u1ed9i ng\u0169 quy\u1ebft \u0111\u1ecbnh l\u01b0u tr\u1eef c\u00e1c giao d\u1ecbch n\u00e0y v\u00e0o m\u1ed9t Historical_Legacy<\/strong> b\u1ea3ng \u0111\u1ec3 duy tr\u00ec c\u00e1c lu\u1ed3ng ki\u1ec3m to\u00e1n m\u00e0 kh\u00f4ng l\u00e0m gi\u00e1n \u0111o\u1ea1n c\u00e1c m\u1ed1i quan h\u1ec7 m\u1edbi.<\/li>\n
                      • Kh\u00f3a b\u1ecb thi\u1ebfu:<\/strong> Trong c\u00e1c tr\u01b0\u1eddng h\u1ee3p m\u00e0 ID kh\u00e1ch h\u00e0ng b\u1ecb thi\u1ebfu trong h\u1ec7 th\u1ed1ng c\u0169, script di chuy\u1ec3n \u0111\u00e3 t\u1ea1o ra m\u1ed9t ID thay th\u1ebf t\u1ea1m th\u1eddi v\u00e0 \u0111\u00e1nh d\u1ea5u b\u1ea3n ghi \u0111\u1ec3 xem x\u00e9t th\u1ee7 c\u00f4ng.<\/li>\n
                      • X\u00f3a m\u1ec1m:<\/strong> Thay v\u00ec x\u00f3a b\u1ea3n ghi m\u1ed9t c\u00e1ch v\u1eadt l\u00fd, l\u01b0\u1ee3c \u0111\u1ed3 m\u1edbi bao g\u1ed3m m\u1ed9t is_active<\/code> c\u1edd. \u0110i\u1ec1u n\u00e0y b\u1ea3o t\u1ed3n l\u1ecbch s\u1eed trong khi \u0111\u1ea3m b\u1ea3o c\u00e1c b\u00e1o c\u00e1o ho\u1ea1t \u0111\u1ed9ng ch\u1ec9 truy v\u1ea5n d\u1eef li\u1ec7u hi\u1ec7n t\u1ea1i.<\/li>\n<\/ul>\n

                        \ud83d\ude80 B\u1ea3o v\u1ec7 l\u01b0\u1ee3c \u0111\u1ed3 cho t\u01b0\u01a1ng lai<\/h2>\n

                        L\u01b0\u1ee3c \u0111\u1ed3 ERD kh\u00f4ng \u0111\u01b0\u1ee3c thi\u1ebft k\u1ebf ch\u1ec9 cho vi\u1ec7c di chuy\u1ec3n hi\u1ec7n t\u1ea1i; n\u00f3 \u0111\u01b0\u1ee3c x\u00e2y d\u1ef1ng \u0111\u1ec3 h\u1ed7 tr\u1ee3 s\u1ef1 ph\u00e1t tri\u1ec3n trong t\u01b0\u01a1ng lai. B\u1eb1ng c\u00e1ch tu\u00e2n th\u1ee7 c\u00e1c nguy\u00ean t\u1eafc chu\u1ea9n h\u00f3a, l\u01b0\u1ee3c \u0111\u1ed3 tr\u1edf n\u00ean linh ho\u1ea1t \u0111\u1ee7 \u0111\u1ec3 h\u1ed7 tr\u1ee3 c\u00e1c t\u00ednh n\u0103ng m\u1edbi m\u00e0 kh\u00f4ng c\u1ea7n ph\u1ea3i thay \u0111\u1ed5i c\u1ea5u tr\u00fac.<\/p>\n

                          \n
                        • Kh\u1ea3 n\u0103ng m\u1edf r\u1ed9ng:<\/strong> S\u1ef1 t\u00e1ch bi\u1ec7t gi\u1eefa c\u00e1c th\u1ef1c th\u1ec3 cho ph\u00e9p m\u1edf r\u1ed9ng ngang. V\u00ed d\u1ee5, b\u1ea3ng Transaction<\/strong> c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c chia theo ng\u00e0y m\u00e0 kh\u00f4ng \u1ea3nh h\u01b0\u1edfng \u0111\u1ebfn b\u1ea3ng Customer<\/strong> b\u1ea3ng.<\/li>\n
                        • Kh\u1ea3 n\u0103ng m\u1edf r\u1ed9ng:<\/strong> N\u1ebfu m\u1ed9t lo\u1ea1i s\u1ea3n ph\u1ea9m m\u1edbi (v\u00ed d\u1ee5: kho\u1ea3n vay th\u1ebf ch\u1ea5p) \u0111\u01b0\u1ee3c th\u00eam v\u00e0o, n\u00f3 c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c li\u00ean k\u1ebft v\u1edbi c\u00e1c th\u1ef1c th\u1ec3 hi\u1ec7n c\u00f3 Customer<\/strong> v\u00e0 Account<\/strong> m\u00e0 kh\u00f4ng c\u1ea7n thay \u0111\u1ed5i l\u01b0\u1ee3c \u0111\u1ed3 c\u1ed1t l\u00f5i.<\/li>\n
                        • T\u00e0i li\u1ec7u:<\/strong> ERD \u0111\u00f3ng vai tr\u00f2 l\u00e0 t\u00e0i li\u1ec7u s\u1ed1ng \u0111\u1ed9ng. C\u00e1c nh\u00e0 ph\u00e1t tri\u1ec3n m\u1edbi c\u00f3 th\u1ec3 hi\u1ec3u ngay m\u00f4 h\u00ecnh d\u1eef li\u1ec7u b\u1eb1ng c\u00e1ch xem x\u00e9t s\u01a1 \u0111\u1ed3, gi\u1ea3m th\u1eddi gian l\u00e0m quen.<\/li>\n<\/ul>\n

                          \ud83d\udca1 Nh\u1eefng b\u00e0i h\u1ecdc c\u1ed1t l\u00f5i cho c\u00e1c ki\u1ebfn tr\u00fac s\u01b0 d\u1eef li\u1ec7u<\/h2>\n

                          Nghi\u00ean c\u1ee9u tr\u01b0\u1eddng h\u1ee3p n\u00e0y l\u00e0m n\u1ed5i b\u1eadt m\u1ed9t s\u1ed1 b\u00e0i h\u1ecdc quan tr\u1ecdng cho c\u00e1c \u0111\u1ed9i ng\u0169 th\u1ef1c hi\u1ec7n c\u00e1c cu\u1ed9c di chuy\u1ec3n t\u01b0\u01a1ng t\u1ef1.<\/p>\n

                            \n
                          • M\u00f4 h\u00ecnh h\u00f3a tr\u01b0\u1edbc khi di chuy\u1ec3n:<\/strong> Kh\u00f4ng bao gi\u1edd th\u1eed di chuy\u1ec3n d\u1eef li\u1ec7u v\u00e0o h\u1ec7 th\u1ed1ng m\u1edbi m\u00e0 kh\u00f4ng c\u00f3 thi\u1ebft k\u1ebf l\u01b0\u1ee3c \u0111\u1ed3 \u0111\u01b0\u1ee3c x\u00e1c nh\u1eadn. ERD l\u00e0 b\u1ea3n v\u1ebd thi\u1ebft k\u1ebf.<\/li>\n
                          • Chu\u1ea9n h\u00f3a \u0111\u1ec3 gi\u1ea3i quy\u1ebft s\u1ef1 tr\u00f9ng l\u1eb7p:<\/strong>\u0110\u1eebng s\u1ee3 chu\u1ea9n h\u00f3a. \u0110\u00f3 l\u00e0 bi\u1ec7n ph\u00e1p ph\u00f2ng th\u1ee7 ch\u00ednh ch\u1ed1ng l\u1ea1i s\u1ef1 b\u1ea5t nh\u1ea5t trong d\u1eef li\u1ec7u.<\/li>\n
                          • X\u00e1c minh li\u00ean t\u1ee5c:<\/strong>Ki\u1ec3m th\u1eed c\u1ea7n di\u1ec5n ra \u1edf m\u1ecdi giai \u0111o\u1ea1n chuy\u1ec3n \u0111\u1ed5i, ch\u1ee9 kh\u00f4ng ch\u1ec9 \u1edf cu\u1ed1i qu\u00e1 tr\u00ecnh.<\/li>\n
                          • T\u00e0i li\u1ec7u c\u00e1c m\u1ed1i quan h\u1ec7:<\/strong>Hi\u1ec3u r\u00f5 t\u00ednh cardinality. Bi\u1ebft \u0111\u01b0\u1ee3c m\u1ed1i quan h\u1ec7 l\u00e0 1:1 hay 1:N s\u1ebd ng\u0103n ng\u1eeba c\u00e1c l\u1ed7i logic trong m\u00f4 h\u00ecnh d\u1eef li\u1ec7u.<\/li>\n
                          • B\u1ea3o t\u1ed3n l\u1ecbch s\u1eed:<\/strong>Chuy\u1ec3n \u0111\u1ed5i kh\u00f4ng ch\u1ec9 li\u00ean quan \u0111\u1ebfn d\u1eef li\u1ec7u hi\u1ec7n t\u1ea1i; n\u00f3 l\u00e0 v\u1ec1 vi\u1ec7c b\u1ea3o t\u1ed3n t\u00ednh to\u00e0n v\u1eb9n c\u1ee7a qu\u00e1 kh\u1ee9.<\/li>\n<\/ul>\n

                            \ud83d\udd17 K\u1ebft lu\u1eadn v\u1ec1 t\u00ednh to\u00e0n v\u1eb9n d\u1eef li\u1ec7u<\/h2>\n

                            S\u1ef1 chuy\u1ec3n \u0111\u1ed5i t\u1eeb h\u1ec7 th\u1ed1ng c\u0169 sang c\u01a1 s\u1edf d\u1eef li\u1ec7u hi\u1ec7n \u0111\u1ea1i hi\u1ebfm khi \u0111\u01a1n gi\u1ea3n ch\u1ec9 l\u00e0 vi\u1ec7c n\u00e2ng l\u00ean v\u00e0 di chuy\u1ec3n. N\u00f3 \u0111\u00f2i h\u1ecfi ph\u1ea3i suy ngh\u0129 l\u1ea1i c\u0103n b\u1ea3n v\u1ec1 c\u00e1ch t\u1ed5 ch\u1ee9c d\u1eef li\u1ec7u. S\u01a1 \u0111\u1ed3 Th\u1ef1c th\u1ec3 – M\u1ed1i quan h\u1ec7 \u0111\u00e3 ch\u1ee9ng minh l\u00e0 t\u00e0i s\u1ea3n qu\u00fd gi\u00e1 nh\u1ea5t trong qu\u00e1 tr\u00ecnh n\u00e0y. N\u00f3 cung c\u1ea5p s\u1ef1 r\u00f5 r\u00e0ng c\u1ea7n thi\u1ebft \u0111\u1ec3 th\u00e1o g\u1ee1 c\u00e1c c\u1ea5u tr\u00fac tr\u00f9ng l\u1eb7p v\u00e0 t\u00e1i x\u00e2y d\u1ef1ng ch\u00fang m\u1ed9t c\u00e1ch to\u00e0n v\u1eb9n.<\/p>\n

                            B\u1eb1ng c\u00e1ch \u01b0u ti\u00ean thi\u1ebft k\u1ebf logic h\u01a1n l\u00e0 tri\u1ec3n khai ngay l\u1eadp t\u1ee9c, t\u1ed5 ch\u1ee9c \u0111\u00e3 \u0111\u1ea1t \u0111\u01b0\u1ee3c m\u00f4i tr\u01b0\u1eddng d\u1eef li\u1ec7u \u1ed5n \u0111\u1ecbnh, m\u1edf r\u1ed9ng \u0111\u01b0\u1ee3c v\u00e0 nh\u1ea5t qu\u00e1n. Vi\u1ec7c gi\u1ea3m thi\u1ec3u s\u1ef1 tr\u00f9ng l\u1eb7p \u0111\u00e3 lo\u1ea1i b\u1ecf m\u1ed9t ngu\u1ed3n r\u1ee7i ro v\u1eadn h\u00e0nh \u0111\u00e1ng k\u1ec3 v\u00e0 t\u1ea1o n\u1ec1n t\u1ea3ng v\u1eefng ch\u1eafc cho c\u00e1c s\u00e1ng ki\u1ebfn ph\u00e2n t\u00edch t\u01b0\u01a1ng lai v\u00e0 tr\u00ed tu\u1ec7 kinh doanh.<\/p>\n

                            S\u1ef1 tr\u00f9ng l\u1eb7p d\u1eef li\u1ec7u kh\u00f4ng ch\u1ec9 l\u00e0 v\u1ea5n \u0111\u1ec1 l\u01b0u tr\u1eef; \u0111\u00f3 l\u00e0 m\u1ed9t r\u1ee7i ro kinh doanh. Gi\u1ea3i quy\u1ebft n\u00f3 th\u00f4ng qua m\u00f4 h\u00ecnh h\u00f3a nghi\u00eam ng\u1eb7t \u0111\u1ea3m b\u1ea3o d\u1eef li\u1ec7u v\u1eabn l\u00e0 t\u00e0i s\u1ea3n \u0111\u00e1ng tin c\u1eady cho ra quy\u1ebft \u0111\u1ecbnh, thay v\u00ec m\u1ed9t g\u00e1nh n\u1eb7ng c\u1ea3n tr\u1edf ti\u1ebfn tri\u1ec3n.<\/p>\n","protected":false},"excerpt":{"rendered":"

                            Trong th\u1ebf gi\u1edbi ki\u1ebfn tr\u00fac d\u1eef li\u1ec7u, \u00edt th\u00e1ch th\u1ee9c n\u00e0o dai d\u1eb3ng b\u1eb1ng v\u1ea5n \u0111\u1ec1 tr\u00f9ng l\u1eb7p d\u1eef li\u1ec7u trong c\u00e1c h\u1ec7 th\u1ed1ng c\u0169. Khi c\u00e1c t\u1ed5 ch\u1ee9c n\u1ed7…<\/p>\n","protected":false},"author":1,"featured_media":52,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_yoast_wpseo_title":"S\u01a1 \u0111\u1ed3 ER Gi\u1ea3i quy\u1ebft V\u1ea5n \u0111\u1ec1 Tr\u00f9ng l\u1eb7p D\u1eef li\u1ec7u trong Chuy\u1ec3n \u0111\u1ed5i H\u1ec7 th\u1ed1ng C\u0169 \ud83d\udcca","_yoast_wpseo_metadesc":"H\u1ecdc c\u00e1ch m\u1ed9t s\u01a1 \u0111\u1ed3 ER chi ti\u1ebft \u0111\u00e3 gi\u1ea3i quy\u1ebft v\u1ea5n \u0111\u1ec1 tr\u00f9ng l\u1eb7p d\u1eef li\u1ec7u trong qu\u00e1 tr\u00ecnh chuy\u1ec3n \u0111\u1ed5i h\u1ec7 th\u1ed1ng c\u0169. Nghi\u00ean c\u1ee9u tr\u01b0\u1eddng h\u1ee3p v\u1ec1 chu\u1ea9n h\u00f3a v\u00e0 thi\u1ebft k\u1ebf l\u01b0\u1ee3c \u0111\u1ed3.","inline_featured_image":false,"fifu_image_url":"","fifu_image_alt":"","footnotes":""},"categories":[6],"tags":[10,11],"class_list":["post-51","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-erd","tag-academic","tag-erd"],"yoast_head":"\nS\u01a1 \u0111\u1ed3 ER Gi\u1ea3i quy\u1ebft V\u1ea5n \u0111\u1ec1 Tr\u00f9ng l\u1eb7p D\u1eef li\u1ec7u trong Chuy\u1ec3n \u0111\u1ed5i H\u1ec7 th\u1ed1ng C\u0169 \ud83d\udcca<\/title>\n<meta name=\"description\" content=\"H\u1ecdc c\u00e1ch m\u1ed9t s\u01a1 \u0111\u1ed3 ER chi ti\u1ebft \u0111\u00e3 gi\u1ea3i quy\u1ebft v\u1ea5n \u0111\u1ec1 tr\u00f9ng l\u1eb7p d\u1eef li\u1ec7u trong qu\u00e1 tr\u00ecnh chuy\u1ec3n \u0111\u1ed5i h\u1ec7 th\u1ed1ng c\u0169. Nghi\u00ean c\u1ee9u tr\u01b0\u1eddng h\u1ee3p v\u1ec1 chu\u1ea9n h\u00f3a v\u00e0 thi\u1ebft k\u1ebf l\u01b0\u1ee3c \u0111\u1ed3.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.we-notes.com\/vn\/er-diagram-data-redundancy-legacy-migration\/\" \/>\n<meta property=\"og:locale\" content=\"vi_VN\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"S\u01a1 \u0111\u1ed3 ER Gi\u1ea3i quy\u1ebft V\u1ea5n \u0111\u1ec1 Tr\u00f9ng l\u1eb7p D\u1eef li\u1ec7u trong Chuy\u1ec3n \u0111\u1ed5i H\u1ec7 th\u1ed1ng C\u0169 \ud83d\udcca\" \/>\n<meta property=\"og:description\" content=\"H\u1ecdc c\u00e1ch m\u1ed9t s\u01a1 \u0111\u1ed3 ER chi ti\u1ebft \u0111\u00e3 gi\u1ea3i quy\u1ebft v\u1ea5n \u0111\u1ec1 tr\u00f9ng l\u1eb7p d\u1eef li\u1ec7u trong qu\u00e1 tr\u00ecnh chuy\u1ec3n \u0111\u1ed5i h\u1ec7 th\u1ed1ng c\u0169. 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