{"id":476344,"date":"2023-08-09T07:28:31","date_gmt":"2023-08-09T07:28:31","guid":{"rendered":""},"modified":"2023-09-05T11:12:33","modified_gmt":"2023-09-05T11:12:33","slug":"composite-key","status":"publish","type":"wiki","link":"https:\/\/oneproxy.pro\/vn\/wiki\/composite-key\/","title":{"rendered":"T\u1ed5 h\u1ee3p ph\u00edm"},"content":{"rendered":"

Kh\u00f3a t\u1ed5ng h\u1ee3p l\u00e0 m\u1ed9t kh\u00e1i ni\u1ec7m \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng trong thi\u1ebft k\u1ebf v\u00e0 qu\u1ea3n l\u00fd c\u01a1 s\u1edf d\u1eef li\u1ec7u \u0111\u1ec3 x\u00e1c \u0111\u1ecbnh duy nh\u1ea5t m\u1ed9t b\u1ea3n ghi trong b\u1ea3ng. Kh\u00f4ng gi\u1ed1ng nh\u01b0 kh\u00f3a \u0111\u01a1n gi\u1ea3n ho\u1eb7c kh\u00f3a m\u1ed9t c\u1ed9t, kh\u00f3a t\u1ed5ng h\u1ee3p bao g\u1ed3m hai ho\u1eb7c nhi\u1ec1u thu\u1ed9c t\u00ednh m\u00e0 khi k\u1ebft h\u1ee3p l\u1ea1i s\u1ebd t\u1ea1o ra m\u00e3 \u0111\u1ecbnh danh duy nh\u1ea5t cho m\u1ed9t b\u1ea3n ghi. Vi\u1ec7c s\u1eed d\u1ee5ng kh\u00f3a t\u1ed5ng h\u1ee3p l\u00e0 c\u1ea7n thi\u1ebft khi m\u1ed9t thu\u1ed9c t\u00ednh duy nh\u1ea5t kh\u00f4ng th\u1ec3 \u0111\u1ea3m b\u1ea3o t\u00ednh duy nh\u1ea5t trong b\u1ea3ng, \u0111\u00f2i h\u1ecfi nhi\u1ec1u thu\u1ed9c t\u00ednh \u0111\u1ec3 \u0111\u1ea3m b\u1ea3o t\u00ednh duy nh\u1ea5t c\u1ee7a m\u1ed7i m\u1ee5c. B\u00e0i vi\u1ebft n\u00e0y s\u1ebd \u0111i s\u00e2u v\u00e0o l\u1ecbch s\u1eed, c\u1ea5u tr\u00fac, lo\u1ea1i, t\u00ednh n\u0103ng v\u00e0 tri\u1ec3n v\u1ecdng trong t\u01b0\u01a1ng lai c\u1ee7a kh\u00f3a t\u1ed5ng h\u1ee3p.<\/p>\n

L\u1ecbch s\u1eed ngu\u1ed3n g\u1ed1c c\u1ee7a Composite Key v\u00e0 l\u1ea7n \u0111\u1ea7u ti\u00ean nh\u1eafc t\u1edbi n\u00f3<\/h2>\n

Kh\u00e1i ni\u1ec7m v\u1ec1 kh\u00f3a t\u1ed5ng h\u1ee3p b\u1eaft ngu\u1ed3n t\u1eeb s\u1ef1 ph\u00e1t tri\u1ec3n ban \u0111\u1ea7u c\u1ee7a h\u1ec7 th\u1ed1ng c\u01a1 s\u1edf d\u1eef li\u1ec7u quan h\u1ec7 v\u00e0o nh\u1eefng n\u0103m 1970. Ti\u1ebfn s\u0129 Edgar F. Codd, \u0111\u01b0\u1ee3c coi l\u00e0 cha \u0111\u1ebb c\u1ee7a m\u00f4 h\u00ecnh c\u01a1 s\u1edf d\u1eef li\u1ec7u quan h\u1ec7, \u0111\u00e3 \u0111\u01b0a ra \u00fd t\u01b0\u1edfng v\u1ec1 kh\u00f3a ch\u00ednh l\u00e0m n\u1ec1n t\u1ea3ng \u0111\u1ec3 x\u00e1c \u0111\u1ecbnh c\u00e1c b\u1ea3n ghi duy nh\u1ea5t trong m\u1ed9t b\u1ea3ng. Tuy nhi\u00ean, khi c\u01a1 s\u1edf d\u1eef li\u1ec7u ng\u00e0y c\u00e0ng ph\u1ee9c t\u1ea1p, r\u00f5 r\u00e0ng l\u00e0 vi\u1ec7c s\u1eed d\u1ee5ng m\u1ed9t thu\u1ed9c t\u00ednh duy nh\u1ea5t l\u00e0m kh\u00f3a ch\u00ednh c\u00f3 th\u1ec3 kh\u00f4ng \u0111\u1ee7 cho t\u1ea5t c\u1ea3 c\u00e1c tr\u01b0\u1eddng h\u1ee3p.<\/p>\n

L\u1ea7n \u0111\u1ea7u ti\u00ean \u0111\u1ec1 c\u1eadp \u0111\u1ebfn kh\u00f3a t\u1ed5ng h\u1ee3p c\u00f3 th\u1ec3 b\u1eaft ngu\u1ed3n t\u1eeb b\u00e0i b\u00e1o chuy\u00ean \u0111\u1ec1 c\u1ee7a Codd c\u00f3 ti\u00eau \u0111\u1ec1 \u201cM\u00f4 h\u00ecnh d\u1eef li\u1ec7u quan h\u1ec7 cho c\u00e1c ng\u00e2n h\u00e0ng d\u1eef li\u1ec7u d\u00f9ng chung l\u1edbn\u201d v\u00e0o n\u0103m 1970. Codd \u0111\u00e3 th\u1ea3o lu\u1eadn v\u1ec1 t\u1ea7m quan tr\u1ecdng c\u1ee7a kh\u00f3a ch\u00ednh v\u00e0 \u0111\u1ec1 xu\u1ea5t r\u1eb1ng trong m\u1ed9t s\u1ed1 tr\u01b0\u1eddng h\u1ee3p, s\u1eed d\u1ee5ng nhi\u1ec1u thu\u1ed9c t\u00ednh l\u00e0m kh\u00f3a t\u1ed5ng h\u1ee3p. c\u1ea7n thi\u1ebft \u0111\u1ec3 \u0111\u1ea3m b\u1ea3o t\u00ednh duy nh\u1ea5t c\u1ee7a h\u1ed3 s\u01a1.<\/p>\n

Th\u00f4ng tin chi ti\u1ebft v\u1ec1 Composite Key: M\u1edf r\u1ed9ng ch\u1ee7 \u0111\u1ec1<\/h2>\n

Kh\u00f3a t\u1ed5ng h\u1ee3p \u0111\u01b0\u1ee3c h\u00ecnh th\u00e0nh b\u1eb1ng c\u00e1ch k\u1ebft h\u1ee3p hai ho\u1eb7c nhi\u1ec1u thu\u1ed9c t\u00ednh t\u1eeb b\u1ea3ng c\u01a1 s\u1edf d\u1eef li\u1ec7u \u0111\u1ec3 t\u1ea1o m\u00e3 \u0111\u1ecbnh danh duy nh\u1ea5t cho m\u1ed7i b\u1ea3n ghi. N\u00f3 \u0111\u00f3ng m\u1ed9t vai tr\u00f2 quan tr\u1ecdng trong vi\u1ec7c duy tr\u00ec t\u00ednh to\u00e0n v\u1eb9n d\u1eef li\u1ec7u v\u00e0 tr\u00e1nh c\u00e1c m\u1ee5c tr\u00f9ng l\u1eb7p. Khi thi\u1ebft k\u1ebf c\u01a1 s\u1edf d\u1eef li\u1ec7u, vi\u1ec7c l\u1ef1a ch\u1ecdn kh\u00f3a t\u1ed5ng h\u1ee3p d\u1ef1a tr\u00ean logic nghi\u1ec7p v\u1ee5 v\u00e0 t\u00ednh ch\u1ea5t c\u1ee7a d\u1eef li\u1ec7u \u0111\u01b0\u1ee3c l\u01b0u tr\u1eef.<\/p>\n

C\u1ea5u tr\u00fac b\u00ean trong c\u1ee7a kh\u00f3a t\u1ed5ng h\u1ee3p v\u00e0 c\u00e1ch th\u1ee9c ho\u1ea1t \u0111\u1ed9ng<\/h3>\n

C\u1ea5u tr\u00fac b\u00ean trong c\u1ee7a kh\u00f3a t\u1ed5ng h\u1ee3p li\u00ean quan \u0111\u1ebfn vi\u1ec7c gh\u00e9p c\u00e1c thu\u1ed9c t\u00ednh th\u00e0nh ph\u1ea7n c\u1ee7a n\u00f3. V\u00ed d\u1ee5: h\u00e3y xem x\u00e9t m\u1ed9t b\u1ea3ng nh\u00e2n vi\u00ean trong \u0111\u00f3 c\u1ea7n c\u00f3 c\u1ea3 ID nh\u00e2n vi\u00ean v\u00e0 ID ph\u00f2ng ban \u0111\u1ec3 nh\u1eadn d\u1ea1ng duy nh\u1ea5t m\u1ed7i nh\u00e2n vi\u00ean. Kh\u00f3a t\u1ed5ng h\u1ee3p trong tr\u01b0\u1eddng h\u1ee3p n\u00e0y s\u1ebd l\u00e0 s\u1ef1 k\u1ebft h\u1ee3p c\u1ee7a hai thu\u1ed9c t\u00ednh n\u00e0y.<\/p>\n

Khi m\u1ed9t b\u1ea3n ghi m\u1edbi \u0111\u01b0\u1ee3c ch\u00e8n v\u00e0o b\u1ea3ng, h\u1ec7 th\u1ed1ng c\u01a1 s\u1edf d\u1eef li\u1ec7u \u0111\u1ea3m b\u1ea3o r\u1eb1ng c\u00e1c gi\u00e1 tr\u1ecb c\u1ee7a kh\u00f3a t\u1ed5ng h\u1ee3p l\u00e0 duy nh\u1ea5t tr\u01b0\u1edbc khi ch\u1ea5p nh\u1eadn m\u1ee5c nh\u1eadp. Vi\u1ec7c x\u00e1c th\u1ef1c t\u01b0\u01a1ng t\u1ef1 \u0111\u01b0\u1ee3c \u00e1p d\u1ee5ng khi c\u1eadp nh\u1eadt ho\u1eb7c x\u00f3a b\u1ea3n ghi. B\u1eb1ng c\u00e1ch th\u1ef1c thi t\u00ednh duy nh\u1ea5t, kh\u00f3a t\u1ed5ng h\u1ee3p ho\u1ea1t \u0111\u1ed9ng nh\u01b0 m\u1ed9t bi\u1ec7n ph\u00e1p b\u1ea3o v\u1ec7 ch\u1ed1ng l\u1ea1i s\u1ef1 kh\u00f4ng nh\u1ea5t qu\u00e1n c\u1ee7a d\u1eef li\u1ec7u.<\/p>\n

Ph\u00e2n t\u00edch c\u00e1c t\u00ednh n\u0103ng ch\u00ednh c\u1ee7a kh\u00f3a t\u1ed5ng h\u1ee3p<\/h2>\n

Kh\u00f3a t\u1ed5ng h\u1ee3p s\u1edf h\u1eefu m\u1ed9t s\u1ed1 t\u00ednh n\u0103ng c\u1ea7n thi\u1ebft khi\u1ebfn ch\u00fang c\u00f3 gi\u00e1 tr\u1ecb trong qu\u1ea3n l\u00fd c\u01a1 s\u1edf d\u1eef li\u1ec7u:<\/p>\n

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  1. \n

    T\u00ednh duy nh\u1ea5t:<\/strong> S\u1ef1 k\u1ebft h\u1ee3p c\u00e1c thu\u1ed9c t\u00ednh trong kh\u00f3a t\u1ed5ng h\u1ee3p \u0111\u1ea3m b\u1ea3o t\u00ednh duy nh\u1ea5t c\u1ee7a c\u00e1c b\u1ea3n ghi trong b\u1ea3ng, ng\u0103n ng\u1eeba s\u1ef1 tr\u00f9ng l\u1eb7p d\u1eef li\u1ec7u.<\/p>\n<\/li>\n

  2. \n

    To\u00e0n v\u1eb9n d\u1eef li\u1ec7u:<\/strong> Kh\u00f3a t\u1ed5ng h\u1ee3p \u0111\u00f3ng vai tr\u00f2 quan tr\u1ecdng trong vi\u1ec7c duy tr\u00ec t\u00ednh to\u00e0n v\u1eb9n c\u1ee7a d\u1eef li\u1ec7u v\u00ec ch\u00fang ng\u0103n ch\u1eb7n vi\u1ec7c ch\u00e8n c\u00e1c b\u1ea3n ghi tr\u00f9ng l\u1eb7p ho\u1eb7c xung \u0111\u1ed9t.<\/p>\n<\/li>\n

  3. \n

    Bi\u1ec3u di\u1ec5n m\u1ed1i quan h\u1ec7:<\/strong> Trong c\u01a1 s\u1edf d\u1eef li\u1ec7u quan h\u1ec7, kh\u00f3a t\u1ed5ng h\u1ee3p th\u01b0\u1eddng \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng \u0111\u1ec3 x\u00e1c \u0111\u1ecbnh m\u1ed1i quan h\u1ec7 gi\u1eefa c\u00e1c b\u1ea3ng, cho ph\u00e9p t\u1ea1o ra c\u00e1c ho\u1ea1t \u0111\u1ed9ng n\u1ed1i hi\u1ec7u qu\u1ea3.<\/p>\n<\/li>\n

  4. \n

    L\u1eadp ch\u1ec9 m\u1ee5c:<\/strong> Kh\u00f3a t\u1ed5ng h\u1ee3p \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng l\u00e0m kh\u00f3a l\u1eadp ch\u1ec9 m\u1ee5c, cho ph\u00e9p truy xu\u1ea5t d\u1eef li\u1ec7u nhanh h\u01a1n v\u00e0 t\u1ed1i \u01b0u h\u00f3a hi\u1ec7u su\u1ea5t truy v\u1ea5n.<\/p>\n<\/li>\n

  5. \n

    M\u1ed1i quan h\u1ec7 ph\u1ee9c t\u1ea1p:<\/strong> Trong tr\u01b0\u1eddng h\u1ee3p m\u1ed9t b\u1ea3ng c\u00f3 nhi\u1ec1u m\u1ed1i quan h\u1ec7 v\u1edbi c\u00e1c b\u1ea3ng kh\u00e1c, kh\u00f3a t\u1ed5ng h\u1ee3p cung c\u1ea5p m\u1ed9t c\u00e1ch m\u1ea1nh m\u1ebd \u0111\u1ec3 th\u1ec3 hi\u1ec7n c\u00e1c k\u1ebft n\u1ed1i ph\u1ee9c t\u1ea1p n\u00e0y.<\/p>\n<\/li>\n<\/ol>\n

    C\u00e1c lo\u1ea1i kh\u00f3a t\u1ed5ng h\u1ee3p<\/h2>\n

    C\u00f3 ba lo\u1ea1i kh\u00f3a t\u1ed5ng h\u1ee3p ch\u00ednh, \u0111\u01b0\u1ee3c ph\u00e2n lo\u1ea1i d\u1ef1a tr\u00ean c\u00e1ch s\u1eed d\u1ee5ng ch\u00fang:<\/p>\n

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    1. \n

      Kh\u00f3a t\u1ed5ng h\u1ee3p t\u1ef1 nhi\u00ean:<\/strong> Kh\u00f3a t\u1ed5ng h\u1ee3p t\u1ef1 nhi\u00ean \u0111\u01b0\u1ee3c h\u00ecnh th\u00e0nh b\u1eb1ng c\u00e1ch s\u1eed d\u1ee5ng c\u00e1c thu\u1ed9c t\u00ednh c\u00f3 m\u1ed1i quan h\u1ec7 logic trong th\u1ebf gi\u1edbi th\u1ef1c. V\u00ed d\u1ee5: b\u1ea3ng \u201cNg\u01b0\u1eddi d\u00f9ng\u201d c\u00f3 th\u1ec3 s\u1eed d\u1ee5ng kh\u00f3a t\u1ed5ng h\u1ee3p t\u1ef1 nhi\u00ean bao g\u1ed3m \u201cFirstName\u201d v\u00e0 \u201cLastName\u201d.<\/p>\n<\/li>\n

    2. \n

      Kh\u00f3a t\u1ed5ng h\u1ee3p thay th\u1ebf:<\/strong> Kh\u00f3a t\u1ed5ng h\u1ee3p thay th\u1ebf l\u00e0 m\u00e3 \u0111\u1ecbnh danh nh\u00e2n t\u1ea1o \u0111\u01b0\u1ee3c t\u1ea1o ch\u1ec9 cho m\u1ee5c \u0111\u00edch c\u01a1 s\u1edf d\u1eef li\u1ec7u. N\u00f3 kh\u00f4ng c\u00f3 \u00fd ngh\u0129a trong th\u1ebf gi\u1edbi th\u1ef1c v\u00e0 th\u01b0\u1eddng l\u00e0 s\u1ed1 nguy\u00ean t\u0103ng t\u1ef1 \u0111\u1ed9ng ho\u1eb7c m\u00e3 \u0111\u1ecbnh danh duy nh\u1ea5t to\u00e0n c\u1ea7u (UUID).<\/p>\n<\/li>\n

    3. \n

      Kh\u00f3a t\u1ed5ng h\u1ee3p n\u01b0\u1edbc ngo\u00e0i:<\/strong> Kh\u00f3a t\u1ed5ng h\u1ee3p ngo\u1ea1i \u0111\u01b0\u1ee3c h\u00ecnh th\u00e0nh b\u1eb1ng c\u00e1ch k\u1ebft h\u1ee3p c\u00e1c thu\u1ed9c t\u00ednh t\u1eeb hai b\u1ea3ng kh\u00e1c nhau \u0111\u1ec3 th\u1ec3 hi\u1ec7n m\u1ed1i quan h\u1ec7 gi\u1eefa ch\u00fang.<\/p>\n<\/li>\n<\/ol>\n

      B\u1ea3ng d\u01b0\u1edbi \u0111\u00e2y t\u00f3m t\u1eaft c\u00e1c lo\u1ea1i kh\u00f3a t\u1ed5ng h\u1ee3p v\u00e0 \u0111\u1eb7c \u0111i\u1ec3m c\u1ee7a ch\u00fang:<\/p>\n\n\n\n\n\n\n\n
      Ki\u1ec3u<\/th>\nS\u1ef1 mi\u00eau t\u1ea3<\/th>\n<\/tr>\n<\/thead>\n
      Kh\u00f3a t\u1ed5ng h\u1ee3p t\u1ef1 nhi\u00ean<\/td>\nS\u1eed d\u1ee5ng c\u00e1c thu\u1ed9c t\u00ednh c\u00f3 \u00fd ngh\u0129a trong th\u1ebf gi\u1edbi th\u1ef1c.<\/td>\n<\/tr>\n
      Kh\u00f3a t\u1ed5ng h\u1ee3p thay th\u1ebf<\/td>\nM\u00e3 \u0111\u1ecbnh danh nh\u00e2n t\u1ea1o kh\u00f4ng c\u00f3 \u00fd ngh\u0129a trong th\u1ebf gi\u1edbi th\u1ef1c.<\/td>\n<\/tr>\n
      Kh\u00f3a t\u1ed5ng h\u1ee3p n\u01b0\u1edbc ngo\u00e0i<\/td>\nBi\u1ec3u th\u1ecb m\u1ed1i quan h\u1ec7 gi\u1eefa hai b\u1ea3ng.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

      C\u00e1ch s\u1eed d\u1ee5ng Kh\u00f3a t\u1ed5ng h\u1ee3p: V\u1ea5n \u0111\u1ec1 v\u00e0 gi\u1ea3i ph\u00e1p<\/h2>\n

      Vi\u1ec7c s\u1eed d\u1ee5ng c\u00e1c kh\u00f3a t\u1ed5ng h\u1ee3p \u0111\u1eb7t ra nh\u1eefng th\u00e1ch th\u1ee9c v\u00e0 c\u00e2n nh\u1eafc nh\u1ea5t \u0111\u1ecbnh:<\/p>\n

      Nh\u1eefng th\u00e1ch th\u1ee9c:<\/h3>\n
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      1. \n

        \u0110\u1ed9 ph\u1ee9c t\u1ea1p:<\/strong> Vi\u1ec7c thi\u1ebft k\u1ebf v\u00e0 qu\u1ea3n l\u00fd b\u1ea3ng b\u1eb1ng c\u00e1c ph\u00edm t\u1ed5ng h\u1ee3p c\u00f3 th\u1ec3 ph\u1ee9c t\u1ea1p h\u01a1n so v\u1edbi vi\u1ec7c s\u1eed d\u1ee5ng c\u00e1c ph\u00edm m\u1ed9t c\u1ed9t.<\/p>\n<\/li>\n

      2. \n

        Thay \u0111\u1ed5i d\u1eef li\u1ec7u:<\/strong> N\u1ebfu c\u00e1c thu\u1ed9c t\u00ednh t\u1ea1o th\u00e0nh kh\u00f3a t\u1ed5ng h\u1ee3p c\u1ea7n \u0111\u01b0\u1ee3c c\u1eadp nh\u1eadt th\u00ec vi\u1ec7c n\u00e0y c\u00f3 th\u1ec3 ph\u1ee9c t\u1ea1p v\u00e0 c\u00f3 th\u1ec3 c\u1ea7n \u0111\u01b0\u1ee3c ch\u0103m s\u00f3c th\u00eam \u0111\u1ec3 duy tr\u00ec t\u00ednh to\u00e0n v\u1eb9n c\u1ee7a d\u1eef li\u1ec7u.<\/p>\n<\/li>\n<\/ol>\n

        C\u00e1c gi\u1ea3i ph\u00e1p:<\/h3>\n
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        1. \n

          Thi\u1ebft k\u1ebf c\u1ea9n th\u1eadn:<\/strong> L\u1eadp k\u1ebf ho\u1ea1ch l\u01b0\u1ee3c \u0111\u1ed3 c\u01a1 s\u1edf d\u1eef li\u1ec7u v\u00e0 ch\u1ecdn c\u00e1c thu\u1ed9c t\u00ednh th\u00edch h\u1ee3p cho kh\u00f3a t\u1ed5ng h\u1ee3p d\u1ef1a tr\u00ean t\u00ednh ch\u1ea5t v\u00e0 m\u1ed1i quan h\u1ec7 c\u1ee7a d\u1eef li\u1ec7u.<\/p>\n<\/li>\n

        2. \n

          T\u1ef1 \u0111\u1ed9ng h\u00f3a:<\/strong> H\u00e3y c\u00e2n nh\u1eafc vi\u1ec7c s\u1eed d\u1ee5ng c\u00e1c h\u1ec7 th\u1ed1ng qu\u1ea3n l\u00fd c\u01a1 s\u1edf d\u1eef li\u1ec7u c\u00f3 th\u1ec3 t\u1ef1 \u0111\u1ed9ng x\u1eed l\u00fd c\u00e1c r\u00e0ng bu\u1ed9c kh\u00f3a t\u1ed5ng h\u1ee3p \u0111\u1ec3 gi\u1ea3m thi\u1ec3u c\u00e1c l\u1ed7i th\u1ee7 c\u00f4ng.<\/p>\n<\/li>\n<\/ol>\n

          C\u00e1c \u0111\u1eb7c \u0111i\u1ec3m ch\u00ednh v\u00e0 so s\u00e1nh v\u1edbi c\u00e1c thu\u1eadt ng\u1eef t\u01b0\u01a1ng t\u1ef1<\/h2>\n

          \u0110\u1ec3 ph\u00e2n bi\u1ec7t kh\u00f3a t\u1ed5ng h\u1ee3p v\u1edbi c\u00e1c kh\u00e1i ni\u1ec7m t\u01b0\u01a1ng t\u1ef1, h\u00e3y so s\u00e1nh ch\u00fang v\u1edbi c\u00e1c lo\u1ea1i kh\u00f3a kh\u00e1c:<\/p>\n\n\n\n\n\n\n\n
          \u0111\u1eb7c tr\u01b0ng<\/th>\nT\u1ed5 h\u1ee3p ph\u00edm<\/th>\nKh\u00f3a ch\u00ednh<\/th>\nKh\u00f3a ngo\u1ea1i<\/th>\n<\/tr>\n<\/thead>\n
          T\u00ednh duy nh\u1ea5t<\/td>\n\u0110\u1ed9c nh\u1ea5t<\/td>\n\u0110\u1ed9c nh\u1ea5t<\/td>\nKh\u00f4ng nh\u1ea5t thi\u1ebft ph\u1ea3i \u0111\u1ed9c \u0111\u00e1o<\/td>\n<\/tr>\n
          Thu\u1ed9c t\u00ednh b\u1eaft bu\u1ed9c<\/td>\nHai ho\u1eb7c nhi\u1ec1u h\u01a1n<\/td>\nM\u1ed9t ho\u1eb7c nhi\u1ec1u<\/td>\nSo kh\u1edbp v\u1edbi kh\u00f3a ch\u00ednh<\/td>\n<\/tr>\n
          M\u1ee5c \u0111\u00edch<\/td>\nX\u00e1c \u0111\u1ecbnh h\u1ed3 s\u01a1<\/td>\nX\u00e1c \u0111\u1ecbnh h\u1ed3 s\u01a1<\/td>\nThi\u1ebft l\u1eadp m\u1ed1i quan h\u1ec7<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

          Quan \u0111i\u1ec3m v\u00e0 c\u00f4ng ngh\u1ec7 c\u1ee7a t\u01b0\u01a1ng lai<\/h2>\n

          Khi c\u01a1 s\u1edf d\u1eef li\u1ec7u ph\u00e1t tri\u1ec3n v\u00e0 x\u1eed l\u00fd c\u00e1c c\u1ea5u tr\u00fac d\u1eef li\u1ec7u ng\u00e0y c\u00e0ng ph\u1ee9c t\u1ea1p, kh\u00f3a t\u1ed5ng h\u1ee3p s\u1ebd ti\u1ebfp t\u1ee5c \u0111\u00f3ng vai tr\u00f2 quan tr\u1ecdng trong vi\u1ec7c \u0111\u1ea3m b\u1ea3o t\u00ednh to\u00e0n v\u1eb9n c\u1ee7a d\u1eef li\u1ec7u v\u00e0 th\u1ec3 hi\u1ec7n m\u1ed1i quan h\u1ec7 ph\u1ee9c t\u1ea1p gi\u1eefa c\u00e1c b\u1ea3n ghi. Vi\u1ec7c \u00e1p d\u1ee5ng c\u01a1 s\u1edf d\u1eef li\u1ec7u NoSQL v\u00e0 c\u01a1 s\u1edf d\u1eef li\u1ec7u \u0111\u1ed3 th\u1ecb c\u00f3 th\u1ec3 mang \u0111\u1ebfn nh\u1eefng c\u01a1 h\u1ed9i m\u1edbi \u0111\u1ec3 t\u1eadn d\u1ee5ng c\u00e1c kh\u00f3a t\u1ed5ng h\u1ee3p theo nh\u1eefng c\u00e1ch \u0111\u1ed9c \u0111\u00e1o.<\/p>\n

          C\u00e1ch s\u1eed d\u1ee5ng ho\u1eb7c li\u00ean k\u1ebft m\u00e1y ch\u1ee7 proxy v\u1edbi kh\u00f3a t\u1ed5ng h\u1ee3p<\/h2>\n

          C\u00e1c m\u00e1y ch\u1ee7 proxy, ch\u1eb3ng h\u1ea1n nh\u01b0 c\u00e1c m\u00e1y ch\u1ee7 do OneProxy (oneproxy.pro) cung c\u1ea5p, l\u00e0 nh\u1eefng c\u00f4ng c\u1ee5 c\u1ea7n thi\u1ebft \u0111\u1ec3 t\u0103ng c\u01b0\u1eddng quy\u1ec1n ri\u00eang t\u01b0, b\u1ea3o m\u1eadt v\u00e0 hi\u1ec7u su\u1ea5t tr\u1ef1c tuy\u1ebfn. M\u1eb7c d\u00f9 kh\u00f4ng li\u00ean quan tr\u1ef1c ti\u1ebfp \u0111\u1ebfn kh\u00e1i ni\u1ec7m kh\u00f3a t\u1ed5ng h\u1ee3p trong thi\u1ebft k\u1ebf c\u01a1 s\u1edf d\u1eef li\u1ec7u, nh\u01b0ng m\u00e1y ch\u1ee7 proxy c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c t\u00edch h\u1ee3p v\u00e0o c\u00e1c chi\u1ebfn l\u01b0\u1ee3c qu\u1ea3n l\u00fd d\u1eef li\u1ec7u \u0111\u1ec3 b\u1ed5 sung th\u00eam m\u1ed9t l\u1edbp b\u1ea3o v\u1ec7.<\/p>\n

          B\u1eb1ng c\u00e1ch \u0111\u1ecbnh tuy\u1ebfn c\u00e1c y\u00eau c\u1ea7u th\u00f4ng qua m\u00e1y ch\u1ee7 proxy, ng\u01b0\u1eddi d\u00f9ng c\u00f3 th\u1ec3 che gi\u1ea5u \u0111\u1ecba ch\u1ec9 IP th\u1ef1c c\u1ee7a h\u1ecd v\u00e0 truy c\u1eadp Internet v\u1edbi t\u00ednh \u1ea9n danh cao h\u01a1n. \u0110i\u1ec1u n\u00e0y c\u00f3 th\u1ec3 \u0111\u1eb7c bi\u1ec7t c\u00f3 gi\u00e1 tr\u1ecb khi x\u1eed l\u00fd d\u1eef li\u1ec7u nh\u1ea1y c\u1ea3m ho\u1eb7c \u0111\u1ed1i v\u1edbi ng\u01b0\u1eddi d\u00f9ng \u1edf c\u00e1c khu v\u1ef1c c\u00f3 quy\u1ec1n truy c\u1eadp h\u1ea1n ch\u1ebf v\u00e0o m\u1ed9t s\u1ed1 trang web ho\u1eb7c d\u1ecbch v\u1ee5 nh\u1ea5t \u0111\u1ecbnh.<\/p>\n

          M\u00e1y ch\u1ee7 proxy c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng c\u00f9ng v\u1edbi kh\u00f3a t\u1ed5ng h\u1ee3p \u0111\u1ec3 cung c\u1ea5p th\u00eam t\u00ednh b\u1ea3o m\u1eadt v\u00e0 ki\u1ec3m so\u00e1t quy\u1ec1n truy c\u1eadp v\u00e0o c\u01a1 s\u1edf d\u1eef li\u1ec7u, h\u1ea1n ch\u1ebf quy\u1ec1n truy c\u1eadp \u0111\u1ed1i v\u1edbi ng\u01b0\u1eddi d\u00f9ng \u0111\u01b0\u1ee3c \u1ee7y quy\u1ec1n v\u00e0 gi\u1ea3m thi\u1ec3u nguy c\u01a1 vi ph\u1ea1m d\u1eef li\u1ec7u.<\/p>\n

          Li\u00ean k\u1ebft li\u00ean quan<\/h2>\n

          \u0110\u1ec3 bi\u1ebft th\u00eam th\u00f4ng tin v\u1ec1 kh\u00f3a t\u1ed5ng h\u1ee3p v\u00e0 thi\u1ebft k\u1ebf c\u01a1 s\u1edf d\u1eef li\u1ec7u, b\u1ea1n c\u00f3 th\u1ec3 th\u1ea5y c\u00e1c t\u00e0i nguy\u00ean sau h\u1eefu \u00edch:<\/p>\n

            \n
          1. Gi\u1edbi thi\u1ec7u v\u1ec1 c\u01a1 s\u1edf d\u1eef li\u1ec7u quan h\u1ec7<\/a><\/li>\n
          2. Thi\u1ebft k\u1ebf c\u01a1 s\u1edf d\u1eef li\u1ec7u: Kh\u00f3a chu\u1ea9n h\u00f3a v\u00e0 kh\u00f3a t\u1ed5ng h\u1ee3p<\/a><\/li>\n
          3. Hi\u1ec3u kh\u00f3a ch\u00ednh, kh\u00f3a ngo\u00e0i v\u00e0 kh\u00f3a t\u1ed5ng h\u1ee3p<\/a><\/li>\n
          4. M\u00e1y ch\u1ee7 proxy v\u00e0 c\u00f4ng d\u1ee5ng c\u1ee7a ch\u00fang<\/a><\/li>\n<\/ol>\n

            T\u00f3m l\u1ea1i, kh\u00f3a t\u1ed5ng h\u1ee3p l\u00e0 m\u1ed9t kh\u00eda c\u1ea1nh c\u01a1 b\u1ea3n c\u1ee7a thi\u1ebft k\u1ebf c\u01a1 s\u1edf d\u1eef li\u1ec7u, \u0111\u1ea3m b\u1ea3o t\u00ednh to\u00e0n v\u1eb9n d\u1eef li\u1ec7u v\u00e0 nh\u1eadn d\u1ea1ng duy nh\u1ea5t c\u00e1c b\u1ea3n ghi trong b\u1ea3ng. Khi c\u00f4ng ngh\u1ec7 ti\u1ebfn b\u1ed9, t\u1ea7m quan tr\u1ecdng c\u1ee7a kh\u00f3a t\u1ed5ng h\u1ee3p s\u1ebd ng\u00e0y c\u00e0ng t\u0103ng l\u00ean, cung c\u1ea5p m\u1ed9t c\u01a1 ch\u1ebf m\u1ea1nh m\u1ebd \u0111\u1ec3 th\u1ec3 hi\u1ec7n c\u00e1c m\u1ed1i quan h\u1ec7 ph\u1ee9c t\u1ea1p v\u00e0 t\u1ed1i \u01b0u h\u00f3a ho\u1ea1t \u0111\u1ed9ng c\u01a1 s\u1edf d\u1eef li\u1ec7u. Khi \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng k\u1ebft h\u1ee3p v\u1edbi m\u00e1y ch\u1ee7 proxy, t\u00ednh b\u1ea3o m\u1eadt v\u00e0 quy\u1ec1n ri\u00eang t\u01b0 c\u1ee7a d\u1eef li\u1ec7u c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c n\u00e2ng cao h\u01a1n n\u1eefa, khi\u1ebfn kh\u00f3a t\u1ed5ng h\u1ee3p tr\u1edf th\u00e0nh t\u00e0i s\u1ea3n qu\u00fd gi\u00e1 trong th\u1eddi \u0111\u1ea1i k\u1ef9 thu\u1eadt s\u1ed1.<\/p>","protected":false},"featured_media":467929,"menu_order":0,"template":"","meta":{"_acf_changed":false,"content-type":"","inline_featured_image":false,"footnotes":""},"class_list":["post-476344","wiki","type-wiki","status-publish","has-post-thumbnail","hentry"],"acf":{"faq_title":"Frequently Asked Questions about Composite Key: An In-Depth Exploration<\/mark>","faq_items":[{"question":"What is a composite key?","answer":"

            A composite key is a concept used in database design where two or more attributes are combined to create a unique identifier for each record within a table. Unlike a simple key, which uses a single attribute, a composite key offers a robust way to ensure data integrity and prevent duplicate entries.<\/p>"},{"question":"Why are composite keys important in database design?","answer":"

            Composite keys are crucial in database design because they guarantee the uniqueness of records within a table. They play a vital role in maintaining data integrity and help avoid data inconsistencies that may arise with a single-column key. By combining multiple attributes, composite keys provide a more comprehensive identifier for each record.<\/p>"},{"question":"How does a composite key work?","answer":"

            A composite key works by concatenating two or more attributes to create a unique identifier for each record. When inserting or updating data, the database system checks that the combination of attribute values forming the composite key is unique, thus preventing duplicate entries.<\/p>"},{"question":"What are the different types of composite keys?","answer":"

            There are three main types of composite keys:<\/p>

            1. Natural Composite Key:<\/strong> It uses attributes with real-world meaning, such as \"FirstName\" and \"LastName\" to identify records.<\/li>
            2. Surrogate Composite Key:<\/strong> It is an artificial identifier with no real-world meaning, often an auto-incremented integer or a universally unique identifier (UUID).<\/li>
            3. Foreign Composite Key:<\/strong> It represents a relationship between two tables by combining attributes from both tables.<\/li><\/ol>"},{"question":"What are the challenges of using composite keys?","answer":"

              Using composite keys can introduce complexity in database design and management. Updating the attributes forming the composite key requires careful handling to maintain data integrity. Additionally, it may require more attention during querying and indexing compared to single-column keys.<\/p>"},{"question":"How can one overcome the challenges of using composite keys?","answer":"

              To overcome the challenges of using composite keys, it is essential to plan the database schema carefully and choose appropriate attributes based on the data's nature and relationships. Database management systems that can automatically handle composite key constraints can also help minimize manual errors.<\/p>"},{"question":"How can proxy servers be associated with composite keys?","answer":"

              Proxy servers, like those provided by OneProxy (oneproxy.pro), offer added security and privacy for online activities. While not directly related to database design, proxy servers can complement the use of composite keys by providing an extra layer of protection and access control to databases. They can help anonymize user IP addresses and restrict access to authorized users.<\/p>"},{"question":"What are the future perspectives of composite keys?","answer":"

              As databases continue to evolve, composite keys will remain essential in ensuring data integrity and representing complex relationships between records. The adoption of NoSQL databases and graph databases may offer new opportunities for leveraging composite keys in unique ways, further enhancing database management and efficiency.<\/p>"}]},"_links":{"self":[{"href":"https:\/\/oneproxy.pro\/vn\/wp-json\/wp\/v2\/wiki\/476344","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/oneproxy.pro\/vn\/wp-json\/wp\/v2\/wiki"}],"about":[{"href":"https:\/\/oneproxy.pro\/vn\/wp-json\/wp\/v2\/types\/wiki"}],"version-history":[{"count":0,"href":"https:\/\/oneproxy.pro\/vn\/wp-json\/wp\/v2\/wiki\/476344\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/oneproxy.pro\/vn\/wp-json\/wp\/v2\/media\/467929"}],"wp:attachment":[{"href":"https:\/\/oneproxy.pro\/vn\/wp-json\/wp\/v2\/media?parent=476344"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}