![\"Kawaii-style](\"https:\/\/www.we-notes.com\/wp-content\/uploads\/2026\/04\/erd-notations-kawaii-comparison-infographic.jpg\"\/)
<\/figure>\n<\/div>\n\ud83c\udfdb\ufe0f K\u00fd hi\u1ec7u Chen: N\u1ec1n t\u1ea3ng l\u1ecbch s\u1eed<\/h2>\n
\u0110\u01b0\u1ee3c Peter Chen gi\u1edbi thi\u1ec7u v\u00e0o n\u0103m 1976, k\u00fd hi\u1ec7u Chen l\u00e0 \u00f4ng t\u1ed5 c\u1ee7a m\u00f4 h\u00ecnh h\u00f3a ER. N\u00f3 \u0111\u01b0\u1ee3c thi\u1ebft k\u1ebf \u0111\u1ec3 d\u1ec5 hi\u1ec3u \u0111\u1ed1i v\u1edbi c\u00e1c nh\u00e0 ph\u00e2n t\u00edch kinh doanh v\u00e0 c\u00e1c b\u00ean li\u00ean quan kh\u00f4ng chuy\u00ean v\u1ec1 k\u1ef9 thu\u1eadt. Ng\u00f4n ng\u1eef h\u00ecnh \u1ea3nh c\u1ee7a n\u00f3 r\u1ea5t \u0111\u1eb7c tr\u01b0ng, d\u1ef1a nhi\u1ec1u v\u00e0o c\u00e1c h\u00ecnh h\u1ecdc \u0111\u1ec3 bi\u1ec3u di\u1ec5n c\u00e1c kh\u00e1i ni\u1ec7m c\u1ed1t l\u00f5i trong l\u00fd thuy\u1ebft c\u01a1 s\u1edf d\u1eef li\u1ec7u.<\/p>\n
C\u00fa ph\u00e1p c\u1ed1t l\u00f5i v\u00e0 c\u00e1c y\u1ebfu t\u1ed1 h\u00ecnh \u1ea3nh<\/h3>\n\n- \n
Th\u1ef1c th\u1ec3:<\/strong>\u0110\u01b0\u1ee3c bi\u1ec3u di\u1ec5n b\u1eb1ng h\u00ecnh ch\u1eef nh\u1eadt. Ch\u00fang ch\u1ee9a kh\u00f3a ch\u00ednh v\u00e0 c\u00e1c thu\u1ed9c t\u00ednh.<\/p>\n<\/li>\n- \n
Thu\u1ed9c t\u00ednh:<\/strong>\u0110\u01b0\u1ee3c bi\u1ec3u di\u1ec5n b\u1eb1ng h\u00ecnh elip k\u1ebft n\u1ed1i v\u1edbi h\u00ecnh ch\u1eef nh\u1eadt th\u1ef1c th\u1ec3. Kh\u00f3a ch\u00ednh th\u01b0\u1eddng \u0111\u01b0\u1ee3c g\u1ea1ch ch\u00e2n.<\/p>\n<\/li>\n- \n
M\u1ed1i quan h\u1ec7:<\/strong>\u0110\u01b0\u1ee3c bi\u1ec3u di\u1ec5n b\u1eb1ng h\u00ecnh thoi k\u1ebft n\u1ed1i hai th\u1ef1c th\u1ec3.<\/p>\n<\/li>\n- \n
S\u1ed1 l\u01b0\u1ee3ng:<\/strong>\u0110\u01b0\u1ee3c bi\u1ec3u th\u1ecb b\u1eb1ng c\u00e1c \u0111\u01b0\u1eddng n\u1ed1i t\u1eeb h\u00ecnh thoi \u0111\u1ebfn c\u00e1c th\u1ef1c th\u1ec3, th\u01b0\u1eddng \u0111\u01b0\u1ee3c \u0111\u00e1nh nh\u00e3n b\u1eb1ng s\u1ed1 ho\u1eb7c ch\u1eef c\u00e1i (1, N, M).<\/p>\n<\/li>\n- \n
Th\u1ef1c th\u1ec3 y\u1ebfu:<\/strong>\u0110\u01b0\u1ee3c th\u1ec3 hi\u1ec7n b\u1eb1ng h\u00ecnh ch\u1eef nh\u1eadt k\u00e9p, cho th\u1ea5y s\u1ef1 ph\u1ee5 thu\u1ed9c v\u00e0o th\u1ef1c th\u1ec3 cha \u0111\u1ec3 t\u1ed3n t\u1ea1i.<\/p>\n<\/li>\n- \n
M\u1ed1i quan h\u1ec7 x\u00e1c \u0111\u1ecbnh:<\/strong>\u0110\u01b0\u1ee3c th\u1ec3 hi\u1ec7n b\u1eb1ng c\u00e1c \u0111\u01b0\u1eddng k\u00e9p n\u1ed1i th\u1ef1c th\u1ec3 y\u1ebfu v\u1edbi cha c\u1ee7a n\u00f3.<\/p>\n<\/li>\n<\/ul>\n\u01afu \u0111i\u1ec3m v\u00e0 tr\u01b0\u1eddng h\u1ee3p s\u1eed d\u1ee5ng<\/h3>\n
K\u00fd hi\u1ec7u Chen t\u1ecf ra v\u01b0\u1ee3t tr\u1ed9i trong c\u00e1c t\u00ecnh hu\u1ed1ng c\u1ea7n gi\u1ea3i th\u00edch thi\u1ebft k\u1ebf c\u01a1 s\u1edf d\u1eef li\u1ec7u cho nh\u1eefng ng\u01b0\u1eddi kh\u00f4ng vi\u1ebft SQL. Vi\u1ec7c s\u1eed d\u1ee5ng h\u00ecnh elip v\u00e0 h\u00ecnh thoi gi\u00fap ph\u00e2n bi\u1ec7t r\u00f5 r\u00e0ng gi\u1eefa m\u1ed9t th\u1ef1c th\u1ec3 (c\u00e1i g\u00ec \u0111\u00f3) v\u00e0 m\u1ed9t m\u1ed1i quan h\u1ec7 (m\u1ed9t h\u00e0nh \u0111\u1ed9ng).<\/p>\n
\n- \n
T\u00e0i li\u1ec7u h\u1ec7 th\u1ed1ng c\u0169:<\/strong>Nhi\u1ec1u h\u1ec7 th\u1ed1ng c\u0169 \u0111\u01b0\u1ee3c thi\u1ebft k\u1ebf theo chu\u1ea9n n\u00e0y. Vi\u1ec7c duy tr\u00ec s\u1ef1 nh\u1ea5t qu\u00e1n v\u1edbi c\u00e1c s\u01a1 \u0111\u1ed3 l\u1ecbch s\u1eed l\u00e0 r\u1ea5t quan tr\u1ecdng.<\/p>\n<\/li>\n- \n
Ph\u00e2n t\u00edch kinh doanh c\u1ea5p cao:<\/strong>Khi th\u1ea3o lu\u1eadn v\u1ec1 y\u00eau c\u1ea7u d\u1eef li\u1ec7u v\u1edbi c\u00e1c qu\u1ea3n l\u00fd s\u1ea3n ph\u1ea9m, h\u00ecnh thoi r\u00f5 r\u00e0ng cho th\u1ea5y m\u1ed1i li\u00ean k\u1ebft gi\u1eefa hai kh\u00e1i ni\u1ec7m kinh doanh.<\/p>\n<\/li>\n- \n
B\u1ed1i c\u1ea3nh h\u1ecdc thu\u1eadt v\u00e0 l\u00fd thuy\u1ebft:<\/strong>Ch\u01b0\u01a1ng tr\u00ecnh h\u1ecdc ng\u00e0nh khoa h\u1ecdc m\u00e1y t\u00ednh th\u01b0\u1eddng d\u1ea1y k\u00fd hi\u1ec7u Chen tr\u01b0\u1edbc \u0111\u1ec3 x\u00e2y d\u1ef1ng n\u1ec1n t\u1ea3ng l\u00fd thuy\u1ebft tr\u01b0\u1edbc khi chuy\u1ec3n sang c\u00e1c phong c\u00e1ch c\u1ee5 th\u1ec3 h\u00f3a tri\u1ec3n khai.<\/p>\n<\/li>\n<\/ul>\nTuy nhi\u00ean, k\u00fd hi\u1ec7u n\u00e0y c\u00f3 th\u1ec3 tr\u1edf n\u00ean r\u1ed1i r\u1eafm khi c\u00e1c m\u1ed1i quan h\u1ec7 ph\u1ee9c t\u1ea1p. C\u00e1c m\u1ed1i quan h\u1ec7 tam ph\u00e2n (m\u1ed1i quan h\u1ec7 gi\u1eefa ba th\u1ef1c th\u1ec3) d\u1ec5 h\u00ecnh dung trong Chen nh\u01b0ng l\u1ea1i kh\u00f3 chuy\u1ec3n \u0111\u1ed5i tr\u1ef1c ti\u1ebfp sang c\u00e1c r\u00e0ng bu\u1ed9c c\u01a1 s\u1edf d\u1eef li\u1ec7u quan h\u1ec7 m\u00e0 kh\u00f4ng c\u1ea7n di\u1ec5n gi\u1ea3i th\u00eam.<\/p>\n
\ud83e\uddb5 K\u00fd hi\u1ec7u ch\u00e2n chim: Chu\u1ea9n chu\u1ea9n quan h\u1ec7<\/h2>\n
C\u0169ng \u0111\u01b0\u1ee3c bi\u1ebft \u0111\u1ebfn v\u1edbi t\u00ean g\u1ecdi k\u00fd hi\u1ec7u IE (K\u1ef9 thu\u1eadt th\u00f4ng tin), k\u00fd hi\u1ec7u ch\u00e2n chim tr\u1edf th\u00e0nh chu\u1ea9n ng\u1ea7m \u0111\u1ecbnh cho thi\u1ebft k\u1ebf c\u01a1 s\u1edf d\u1eef li\u1ec7u quan h\u1ec7 v\u00e0o cu\u1ed1i th\u1ebf k\u1ef7 20. N\u00f3 r\u1ea5t th\u1ef1c ti\u1ec5n \u0111\u1ed1i v\u1edbi c\u00e1c qu\u1ea3n tr\u1ecb vi\u00ean c\u01a1 s\u1edf d\u1eef li\u1ec7u v\u00e0 k\u1ef9 s\u01b0 backend. T\u00ean g\u1ecdi xu\u1ea5t ph\u00e1t t\u1eeb h\u00ecnh d\u1ea1ng d\u00f9ng \u0111\u1ec3 bi\u1ec3u di\u1ec5n ph\u00eda “nhi\u1ec1u” c\u1ee7a m\u1ed9t m\u1ed1i quan h\u1ec7, tr\u00f4ng gi\u1ed1ng nh\u01b0 ch\u00e2n c\u1ee7a m\u1ed9t con chim c\u00fat.<\/p>\n
C\u00fa ph\u00e1p c\u1ed1t l\u00f5i v\u00e0 c\u00e1c y\u1ebfu t\u1ed1 h\u00ecnh \u1ea3nh<\/h3>\n\n- \n
C\u00e1c th\u1ef1c th\u1ec3:<\/strong>\u0110\u01b0\u1ee3c bi\u1ec3u di\u1ec5n b\u1eb1ng c\u00e1c h\u00ecnh ch\u1eef nh\u1eadt (th\u01b0\u1eddng ch\u1ec9 l\u00e0 t\u00ean b\u1ea3ng trong c\u00e1c c\u00f4ng c\u1ee5 hi\u1ec7n \u0111\u1ea1i).<\/p>\n<\/li>\n- \n
C\u00e1c m\u1ed1i quan h\u1ec7:<\/strong>\u0110\u01b0\u1ee3c bi\u1ec3u di\u1ec5n b\u1eb1ng c\u00e1c \u0111\u01b0\u1eddng th\u1eb3ng n\u1ed1i c\u00e1c b\u1ea3ng v\u1edbi nhau.<\/p>\n<\/li>\n- \n
S\u1ed1 l\u01b0\u1ee3ng (k\u00fd hi\u1ec7u \u201cCh\u00e2n qu\u1ea1\u201d):<\/strong>M\u1ed9t k\u00fd hi\u1ec7u ba nh\u00e1nh (gi\u1ed1ng nh\u01b0 ch\u00e2n c\u1ee7a con qu\u1ea1) cho bi\u1ebft ph\u00eda \u201cnhi\u1ec1u\u201d trong m\u1ed1i quan h\u1ec7.<\/p>\n<\/li>\n- \n
T\u00ednh ch\u1ea5t tham gia:<\/strong>M\u1ed9t thanh ngang (|) cho bi\u1ebft tham gia b\u1eaft bu\u1ed9c (ph\u1ea3i t\u1ed3n t\u1ea1i), trong khi m\u1ed9t v\u00f2ng tr\u00f2n (o) cho bi\u1ebft tham gia t\u00f9y ch\u1ecdn (c\u00f3 th\u1ec3 l\u00e0 null).<\/p>\n<\/li>\n- \n
Kh\u00f3a ch\u00ednh:<\/strong>Th\u01b0\u1eddng \u0111\u01b0\u1ee3c \u0111\u00e1nh d\u1ea5u b\u1eb1ng bi\u1ec3u t\u01b0\u1ee3ng ch\u00eca kh\u00f3a ho\u1eb7c ch\u00fa th\u00edch v\u0103n b\u1ea3n c\u1ee5 th\u1ec3 b\u00ean c\u1ea1nh thu\u1ed9c t\u00ednh.<\/p>\n<\/li>\n<\/ul>\n\u01afu \u0111i\u1ec3m v\u00e0 c\u00e1c tr\u01b0\u1eddng h\u1ee3p s\u1eed d\u1ee5ng<\/h3>\n
K\u00fd hi\u1ec7u ch\u00e2n qu\u1ea1 \u0111\u01b0\u1ee3c t\u1ed1i \u01b0u h\u00f3a \u0111\u1ec3 \u00e1nh x\u1ea1 tr\u1ef1c ti\u1ebfp sang c\u00e1c l\u1ec7nh DDL SQL. N\u1ebfu b\u1ea1n \u0111ang vi\u1ebft l\u01b0\u1ee3c \u0111\u1ed3, \u0111\u00e2y c\u00f3 l\u1ebd l\u00e0 ng\u00f4n ng\u1eef tr\u1ef1c quan b\u1ea1n \u0111ang s\u1eed d\u1ee5ng.<\/p>\n
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Thi\u1ebft k\u1ebf c\u01a1 s\u1edf d\u1eef li\u1ec7u quan h\u1ec7:<\/strong>N\u00f3 \u00e1nh x\u1ea1 r\u00f5 r\u00e0ng sang c\u00e1c kh\u00f3a ngo\u1ea1i v\u00e0 kh\u00f3a ch\u00ednh trong c\u00e1c c\u01a1 s\u1edf d\u1eef li\u1ec7u SQL nh\u01b0 PostgreSQL, MySQL ho\u1eb7c SQL Server.<\/p>\n<\/li>\n- \n
T\u00e0i li\u1ec7u l\u01b0\u1ee3c \u0111\u1ed3:<\/strong>N\u00f3 l\u00e0 ti\u00eau chu\u1ea9n ng\u00e0nh cho t\u00e0i li\u1ec7u k\u1ef9 thu\u1eadt trong c\u00e1c nh\u00f3m ph\u00e1t tri\u1ec3n.<\/p>\n<\/li>\n- \n
R\u00f5 r\u00e0ng v\u1ec1 t\u00ednh to\u00e0n v\u1eb9n d\u1eef li\u1ec7u:<\/strong>Vi\u1ec7c s\u1eed d\u1ee5ng thanh ngang v\u00e0 v\u00f2ng tr\u00f2n x\u00e1c \u0111\u1ecbnh r\u00f5 r\u00e0ng c\u00e1c r\u00e0ng bu\u1ed9c kh\u1ea3 n\u0103ng null, \u0111i\u1ec1u n\u00e0y r\u1ea5t quan tr\u1ecdng \u0111\u1ed1i v\u1edbi logic ph\u00eda backend.<\/p>\n<\/li>\n<\/ul>\nK\u00fd hi\u1ec7u n\u00e0y \u00edt tr\u1eebu t\u01b0\u1ee3ng h\u01a1n Chen. N\u00f3 gi\u1ea3 \u0111\u1ecbnh ng\u01b0\u1eddi xem hi\u1ec3u kh\u00e1i ni\u1ec7m v\u1ec1 b\u1ea3ng v\u00e0 kh\u00f3a ngo\u1ea1i. \u0110i\u1ec1u n\u00e0y khi\u1ebfn n\u00f3 \u00edt ph\u00f9 h\u1ee3p cho c\u00e1c cu\u1ed9c h\u1ecdp kinh doanh c\u1ea5p cao nh\u01b0ng l\u1ea1i l\u00fd t\u01b0\u1edfng cho l\u1eadp k\u1ebf ho\u1ea1ch sprint k\u1ef9 thu\u1eadt.<\/p>\n
\ud83d\udcd0 S\u01a1 \u0111\u1ed3 l\u1edbp UML: C\u1ea7u n\u1ed1i h\u01b0\u1edbng \u0111\u1ed1i t\u01b0\u1ee3ng<\/h2>\n
Ng\u00f4n ng\u1eef m\u00f4 h\u00ecnh h\u00f3a th\u1ed1ng nh\u1ea5t (UML) \u0111\u01b0\u1ee3c ph\u00e1t tri\u1ec3n nh\u1eb1m chu\u1ea9n h\u00f3a thi\u1ebft k\u1ebf ph\u1ea7n m\u1ec1m tr\u00ean nhi\u1ec1u m\u00f4 h\u00ecnh kh\u00e1c nhau. M\u1eb7c d\u00f9 UML bao g\u1ed3m nhi\u1ec1u lo\u1ea1i s\u01a1 \u0111\u1ed3, s\u01a1 \u0111\u1ed3 l\u1edbp l\u00e0 lo\u1ea1i th\u01b0\u1eddng \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng nh\u1ea5t \u0111\u1ec3 m\u00f4 h\u00ecnh h\u00f3a c\u01a1 s\u1edf d\u1eef li\u1ec7u trong b\u1ed1i c\u1ea3nh h\u01b0\u1edbng \u0111\u1ed1i t\u01b0\u1ee3ng. N\u00f3 t\u1ea1o ra s\u1ef1 li\u00ean k\u1ebft gi\u1eefa c\u1ea5u tr\u00fac m\u00e3 ngu\u1ed3n v\u00e0 c\u1ea5u tr\u00fac d\u1eef li\u1ec7u.<\/p>\n
Ng\u1eef ph\u00e1p c\u1ed1t l\u00f5i v\u00e0 c\u00e1c y\u1ebfu t\u1ed1 tr\u1ef1c quan<\/h3>\n\n- \n
L\u1edbp:<\/strong>H\u00ecnh ch\u1eef nh\u1eadt \u0111\u01b0\u1ee3c chia th\u00e0nh ba ph\u1ea7n: T\u00ean, Thu\u1ed9c t\u00ednh v\u00e0 Thao t\u00e1c (ph\u01b0\u01a1ng th\u1ee9c).<\/p>\n<\/li>\n- \n
C\u00e1c m\u1ed1i quan h\u1ec7:<\/strong>C\u00e1c \u0111\u01b0\u1eddng n\u1ed1i c\u00e1c l\u1edbp v\u1edbi \u0111\u1ea7u m\u0169i t\u00ean c\u1ee5 th\u1ec3 \u0111\u1ec3 ch\u1ec9 h\u01b0\u1edbng v\u00e0 lo\u1ea1i m\u1ed1i quan h\u1ec7.<\/p>\n<\/li>\n- \n
Li\u00ean k\u1ebft:<\/strong>M\u1ed9t \u0111\u01b0\u1eddng \u0111\u01a1n gi\u1ea3n. Cho bi\u1ebft m\u1ed1i quan h\u1ec7 t\u1ed3n t\u1ea1i.<\/p>\n<\/li>\n- \n
T\u1ed5 h\u1ee3p:<\/strong>M\u1ed9t h\u00ecnh kim c\u01b0\u01a1ng r\u1ed7ng \u1edf m\u1ed9t \u0111\u1ea7u. Cho bi\u1ebft m\u1ed1i quan h\u1ec7 \u201cto\u00e0n th\u1ec3-ph\u1ea7n\u201d, trong \u0111\u00f3 c\u00e1c ph\u1ea7n c\u00f3 th\u1ec3 t\u1ed3n t\u1ea1i \u0111\u1ed9c l\u1eadp.<\/p>\n<\/li>\n- \n
Th\u00e0nh ph\u1ea7n:<\/strong>M\u1ed9t h\u00ecnh thoi \u0111\u1ea7y. Ch\u1ec9 ra m\u1ed1i quan h\u1ec7 ph\u1ee5 thu\u1ed9c v\u00f2ng \u0111\u1eddi nghi\u00eam ng\u1eb7t; n\u1ebfu to\u00e0n b\u1ed9 b\u1ecb h\u1ee7y, c\u00e1c b\u1ed9 ph\u1eadn c\u0169ng s\u1ebd b\u1ecb h\u1ee7y.<\/p>\n<\/li>\n- \n
\u0110a d\u1ea1ng:<\/strong>C\u00e1c s\u1ed1 \u0111\u01b0\u1ee3c \u0111\u1eb7t g\u1ea7n hai \u0111\u1ea7u c\u1ee7a \u0111\u01b0\u1eddng n\u1ed1i (v\u00ed d\u1ee5: 0..1, 1..*, 0..*). V\u1ec1 m\u1eb7t ch\u1ee9c n\u0103ng t\u01b0\u01a1ng t\u1ef1 nh\u01b0 k\u00fd hi\u1ec7u Crow\u2019s Foot nh\u01b0ng s\u1eed d\u1ee5ng k\u00fd hi\u1ec7u to\u00e1n h\u1ecdc.<\/p>\n<\/li>\n<\/ul>\n\u0110i\u1ec3m m\u1ea1nh v\u00e0 tr\u01b0\u1eddng h\u1ee3p s\u1eed d\u1ee5ng<\/h3>\n
S\u01a1 \u0111\u1ed3 l\u1edbp UML l\u00e0 thi\u1ebft y\u1ebfu khi c\u01a1 s\u1edf d\u1eef li\u1ec7u kh\u00f4ng ph\u1ea3i l\u00e0 \u0111i\u1ec3m t\u1eadp trung duy nh\u1ea5t. Ch\u00fang l\u00e0 l\u1edbp k\u1ebft n\u1ed1i gi\u1eefa m\u00e3 ph\u00eda backend v\u00e0 l\u1edbp l\u01b0u tr\u1eef b\u1ec1n v\u1eefng.<\/p>\n
\n- \n
\u00c1nh x\u1ea1 ORM:<\/strong>C\u00e1c tr\u00ecnh \u00e1nh x\u1ea1 \u0111\u1ed1i t\u01b0\u1ee3ng-quan h\u1ec7 (ORMs) ph\u1ee5 thu\u1ed9c r\u1ea5t nhi\u1ec1u v\u00e0o c\u00e1c m\u1ed1i quan h\u1ec7 ki\u1ec3u UML \u0111\u1ec3 hi\u1ec3u c\u00e1ch \u00e1nh x\u1ea1 c\u00e1c l\u1edbp v\u00e0o b\u1ea3ng.<\/p>\n<\/li>\n- \n
Ki\u1ebfn tr\u00fac Full-Stack:<\/strong>Khi c\u00e1c \u0111\u1ed9i ng\u0169 frontend, backend v\u00e0 c\u01a1 s\u1edf d\u1eef li\u1ec7u c\u1ea7n th\u1ed1ng nh\u1ea5t v\u1ec1 c\u1ea5u tr\u00fac d\u1eef li\u1ec7u, UML cung c\u1ea5p m\u1ed9t t\u1eeb v\u1ef1ng chung.<\/p>\n<\/li>\n- \n
C\u00e1c m\u1ed1i quan h\u1ec7 ph\u1ee9c t\u1ea1p:<\/strong>UML x\u1eed l\u00fd k\u1ebf th\u1eeba, kh\u00e1i qu\u00e1t h\u00f3a v\u00e0 tri\u1ec3n khai giao di\u1ec7n t\u1ed1t h\u01a1n so v\u1edbi c\u00e1c k\u00fd hi\u1ec7u thu\u1ea7n t\u00fay d\u1ef1a tr\u00ean quan h\u1ec7.<\/p>\n<\/li>\n<\/ul>\nNh\u01b0\u1ee3c \u0111i\u1ec3m l\u00e0 s\u1ef1 r\u01b0\u1eddm r\u00e0. M\u1ed9t m\u1ed1i quan h\u1ec7 b\u1ea3ng \u0111\u01a1n gi\u1ea3n trong k\u00fd hi\u1ec7u Crow\u2019s Foot c\u00f3 th\u1ec3 y\u00eau c\u1ea7u m\u1ed9t \u0111\u1ecbnh ngh\u0129a l\u1edbp ph\u1ee9c t\u1ea1p trong UML, bao g\u1ed3m c\u00e1c ph\u01b0\u01a1ng th\u1ee9c v\u00e0 thu\u1ed9c t\u00ednh kh\u00f4ng li\u00ean quan \u0111\u1ebfn c\u01a1 s\u1edf d\u1eef li\u1ec7u. \u0110i\u1ec1u n\u00e0y c\u00f3 th\u1ec3 d\u1eabn \u0111\u1ebfn nh\u1ea7m l\u1eabn n\u1ebfu s\u01a1 \u0111\u1ed3 \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng ch\u1ec9 \u0111\u1ec3 sinh l\u01b0\u1ee3c \u0111\u1ed3.<\/p>\n
\ud83d\udcca So s\u00e1nh song song<\/h2>\n
\u0110\u1ec3 d\u1ec5 d\u00e0ng \u0111\u01b0a ra quy\u1ebft \u0111\u1ecbnh h\u01a1n, \u0111\u00e2y l\u00e0 ph\u00e2n t\u00edch c\u00e1ch c\u00e1c k\u00fd hi\u1ec7u n\u00e0y x\u1eed l\u00fd c\u00e1c t\u00ecnh hu\u1ed1ng m\u00f4 h\u00ecnh h\u00f3a c\u1ee5 th\u1ec3.<\/p>\n
\n\n \n\n\nT\u00ednh n\u0103ng<\/p>\n<\/th>\n
\nK\u00fd hi\u1ec7u Chen<\/p>\n<\/th>\n
\nK\u00fd hi\u1ec7u Crow\u2019s Foot<\/p>\n<\/th>\n
\nS\u01a1 \u0111\u1ed3 l\u1edbp UML<\/p>\n<\/th>\n<\/tr>\n
\n\n\u0110\u1ed1i t\u01b0\u1ee3ng ch\u00ednh<\/strong><\/p>\n<\/td>\n\nNh\u00e0 ph\u00e2n t\u00edch kinh doanh, h\u1ecdc gi\u1ea3<\/p>\n<\/td>\n
\nDBAs, K\u1ef9 s\u01b0 backend<\/p>\n<\/td>\n
\nL\u1eadp tr\u00ecnh vi\u00ean full-stack, Ki\u1ebfn tr\u00fac s\u01b0<\/p>\n<\/td>\n<\/tr>\n
\n\nBi\u1ec3u di\u1ec5n th\u1ef1c th\u1ec3<\/strong><\/p>\n<\/td>\n\nH\u00ecnh ch\u1eef nh\u1eadt<\/p>\n<\/td>\n
\nH\u00ecnh ch\u1eef nh\u1eadt (B\u1ea3ng)<\/p>\n<\/td>\n
\nH\u1ed9p l\u1edbp (T\u00ean\/Thu\u1ed9c t\u00ednh\/Ph\u01b0\u01a1ng th\u1ee9c)<\/p>\n<\/td>\n<\/tr>\n
\n\nBi\u1ec3u di\u1ec5n m\u1ed1i quan h\u1ec7<\/strong><\/p>\n<\/td>\n\nH\u00ecnh thoi<\/p>\n<\/td>\n
\n\u0110\u01b0\u1eddng n\u1ed1i v\u1edbi k\u00fd hi\u1ec7u<\/p>\n<\/td>\n
\n\u0110\u01b0\u1eddng v\u1edbi \u0111\u1ea7u m\u0169i t\u00ean\/ h\u00ecnh thoi<\/p>\n<\/td>\n<\/tr>\n
\n\nK\u00fd hi\u1ec7u cardinality<\/strong><\/p>\n<\/td>\n\nNh\u00e3n (1, N, M)<\/p>\n<\/td>\n
\nCrow\u2019s Foot + Thanh\/ H\u00ecnh tr\u00f2n<\/p>\n<\/td>\n
\nTo\u00e1n h\u1ecdc (0..1, *)<\/p>\n<\/td>\n<\/tr>\n
\n\nCh\u1ec9 th\u1ecb kh\u1ea3 n\u0103ng null<\/strong><\/p>\n<\/td>\n\nNg\u1ea7m \u0111\u1ecbnh ho\u1eb7c v\u0103n b\u1ea3n<\/p>\n<\/td>\n
\nR\u00f5 r\u00e0ng (H\u00ecnh tr\u00f2n = T\u00f9y ch\u1ecdn)<\/p>\n<\/td>\n
\nR\u00f5 r\u00e0ng (B\u1ed9i s\u1ed1)<\/p>\n<\/td>\n<\/tr>\n
\n\nT\u1ed1t nh\u1ea5t cho<\/strong><\/p>\n<\/td>\n\nM\u00f4 h\u00ecnh kh\u00e1i ni\u1ec7m<\/p>\n<\/td>\n
\nM\u00f4 h\u00ecnh logic\/ v\u1eadt l\u00fd<\/p>\n<\/td>\n
\nM\u00f4 h\u00ecnh tri\u1ec3n khai<\/p>\n<\/td>\n<\/tr>\n
\n\n\u0110\u1ed9 ph\u1ee9c t\u1ea1p<\/strong><\/p>\n<\/td>\n\nCao \u0111\u1ed1i v\u1edbi c\u00e1c li\u00ean k\u1ebft tam ph\u00e2n<\/p>\n<\/td>\n
\nTrung b\u00ecnh<\/p>\n<\/td>\n
\nCao \u0111\u1ed1i v\u1edbi k\u1ebf th\u1eeba<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
\ud83d\udd0d Ch\u1ecdn k\u00fd hi\u1ec7u ph\u00f9 h\u1ee3p cho h\u1ec7 th\u1ed1ng c\u1ee7a b\u1ea1n<\/h2>\n
Kh\u00f4ng c\u00f3 k\u00fd hi\u1ec7u ‘t\u1ed1t nh\u1ea5t’ duy nh\u1ea5t. L\u1ef1a ch\u1ecdn \u0111\u00fang ph\u1ee5 thu\u1ed9c v\u00e0o giai \u0111o\u1ea1n v\u00f2ng \u0111\u1eddi c\u1ee7a d\u1ef1 \u00e1n v\u00e0 c\u00e1c c\u00f4ng ngh\u1ec7 tham gia.<\/p>\n
T\u00ecnh hu\u1ed1ng 1: Kho d\u1eef li\u1ec7u quan h\u1ec7 thu\u1ea7n t\u00fay<\/h3>\n
N\u1ebfu b\u1ea1n \u0111ang thi\u1ebft k\u1ebf m\u1ed9t kho d\u1eef li\u1ec7u ho\u1eb7c h\u1ec7 th\u1ed1ng giao d\u1ecbch m\u00e0 tr\u1ecdng t\u00e2m ho\u00e0n to\u00e0n l\u00e0 c\u00e1c b\u1ea3ng SQL v\u00e0 hi\u1ec7u su\u1ea5t truy v\u1ea5n, Crow\u2019s Foot l\u00e0 l\u1ef1a ch\u1ecdn hi\u1ec7u qu\u1ea3 nh\u1ea5t. N\u00f3 gi\u1ea3m thi\u1ec3u t\u1ea3i nh\u1eadn th\u1ee9c v\u1ec1 c\u00e1c kh\u00e1i ni\u1ec7m \u0111\u1ed1i t\u01b0\u1ee3ng v\u00e0 t\u1ed1i \u0111a h\u00f3a \u0111\u1ed9 r\u00f5 r\u00e0ng v\u1ec1 r\u00e0ng bu\u1ed9c. Khi m\u1ed9t nh\u00e0 ph\u00e1t tri\u1ec3n nh\u00ecn v\u00e0o s\u01a1 \u0111\u1ed3 Crow\u2019s Foot, h\u1ecd bi\u1ebft ch\u00ednh x\u00e1c kh\u00f3a ngo\u1ea1i n\u00e0o c\u1ea7n vi\u1ebft.<\/p>\n
\n- \n
Tr\u1ecdng t\u00e2m:<\/strong> T\u00ednh to\u00e0n v\u1eb9n d\u1eef li\u1ec7u v\u00e0 t\u1ed1c \u0111\u1ed9 truy v\u1ea5n.<\/p>\n<\/li>\n- \n
Khuy\u1ebfn ngh\u1ecb:<\/strong>S\u1eed d\u1ee5ng Crow\u2019s Foot cho l\u1edbp s\u01a1 \u0111\u1ed3 v\u1eadt l\u00fd.<\/p>\n<\/li>\n<\/ul>\nT\u00ecnh hu\u1ed1ng 2: Microservices v\u00e0 Thi\u1ebft k\u1ebf h\u01b0\u1edbng mi\u1ec1n<\/h3>\n
Trong ki\u1ebfn tr\u00fac microservices, c\u00e1c \u0111\u1ed9i th\u01b0\u1eddng ho\u1ea1t \u0111\u1ed9ng trong c\u00e1c ng\u1eef c\u1ea3nh \u0111\u01b0\u1ee3c gi\u1edbi h\u1ea1n. S\u01a1 \u0111\u1ed3 l\u1edbp UML c\u00f3 gi\u00e1 tr\u1ecb \u1edf \u0111\u00e2y \u0111\u1ec3 x\u00e1c \u0111\u1ecbnh ranh gi\u1edbi gi\u1eefa c\u00e1c d\u1ecbch v\u1ee5. Ch\u00fang gi\u00fap h\u00ecnh dung c\u00e1ch m\u1ed9t th\u1ef1c th\u1ec3 trong m\u1ed9t d\u1ecbch v\u1ee5 li\u00ean quan \u0111\u1ebfn th\u1ef1c th\u1ec3 trong d\u1ecbch v\u1ee5 kh\u00e1c, th\u01b0\u1eddng th\u00f4ng qua h\u1ee3p \u0111\u1ed3ng API thay v\u00ec c\u00e1c li\u00ean k\u1ebft c\u01a1 s\u1edf d\u1eef li\u1ec7u tr\u1ef1c ti\u1ebfp.<\/p>\n
\n- \n
Tr\u1ecdng t\u00e2m:<\/strong> Ranh gi\u1edbi d\u1ecbch v\u1ee5 v\u00e0 \u00e1nh x\u1ea1 \u0111\u1ed1i t\u01b0\u1ee3ng.<\/p>\n<\/li>\n- \n
Khuy\u1ebfn ngh\u1ecb:<\/strong> S\u1eed d\u1ee5ng UML cho m\u00f4 h\u00ecnh mi\u1ec1n, sau \u0111\u00f3 chuy\u1ec3n \u0111\u1ed5i sang bi\u1ec3u t\u01b0\u1ee3ng Crow\u2019s Foot cho c\u01a1 s\u1edf d\u1eef li\u1ec7u d\u1ecbch v\u1ee5 c\u1ee5 th\u1ec3.<\/p>\n<\/li>\n<\/ul>\nT\u00ecnh hu\u1ed1ng 3: Chuy\u1ec3n \u0111\u1ed5i t\u1eeb h\u1ec7 th\u1ed1ng c\u0169 v\u00e0 ki\u1ec3m to\u00e1n<\/h3>\n
Khi ki\u1ec3m to\u00e1n m\u1ed9t h\u1ec7 th\u1ed1ng hi\u1ec7n c\u00f3 ho\u1eb7c chuy\u1ec3n \u0111\u1ed5i t\u1eeb n\u1ec1n t\u1ea3ng c\u0169, k\u00fd hi\u1ec7u Chen c\u00f3 th\u1ec3 xu\u1ea5t hi\u1ec7n trong t\u00e0i li\u1ec7u. Hi\u1ec3u r\u00f5 n\u00f3 l\u00e0 \u0111i\u1ec1u c\u1ea7n thi\u1ebft \u0111\u1ec3 chuy\u1ec3n \u0111\u1ed5i ch\u00ednh x\u00e1c. B\u1ea1n ph\u1ea3i c\u00f3 kh\u1ea3 n\u0103ng chuy\u1ec3n \u0111\u1ed5i c\u00e1c h\u00ecnh thoi v\u00e0 h\u00ecnh elip tr\u1edf l\u1ea1i c\u1ea5u tr\u00fac b\u1ea3ng hi\u1ec7n \u0111\u1ea1i.<\/p>\n
\n- \n
Tr\u1ecdng t\u00e2m:<\/strong>B\u1ea3o t\u1ed3n logic kinh doanh.<\/p>\n<\/li>\n- \n
Khuy\u1ebfn ngh\u1ecb:<\/strong>Chuy\u1ec3n \u0111\u1ed5i k\u00fd hi\u1ec7u Chen sang Crow\u2019s Foot \u0111\u1ec3 tri\u1ec3n khai, \u0111\u1ed3ng th\u1eddi gi\u1eef l\u1ea1i k\u00fd hi\u1ec7u Chen g\u1ed1c \u0111\u1ec3 tham kh\u1ea3o.<\/p>\n<\/li>\n<\/ul>\n\ud83d\udee0\ufe0f C\u00e1c th\u1ef1c h\u00e0nh t\u1ed1t nh\u1ea5t cho m\u00f4 h\u00ecnh h\u00f3a d\u1eef li\u1ec7u<\/h2>\n
D\u00f9 ch\u1ecdn k\u00fd hi\u1ec7u n\u00e0o, m\u1ed9t s\u1ed1 nguy\u00ean t\u1eafc nh\u1ea5t \u0111\u1ecbnh \u0111\u1ec1u \u00e1p d\u1ee5ng ph\u1ed5 bi\u1ebfn \u0111\u1ec3 \u0111\u1ea3m b\u1ea3o h\u1ec7 th\u1ed1ng c\u00f3 th\u1ec3 duy tr\u00ec v\u00e0 m\u1edf r\u1ed9ng \u0111\u01b0\u1ee3c.<\/p>\n
\n- \n
T\u00ednh nh\u1ea5t qu\u00e1n l\u00e0 ch\u00eca kh\u00f3a:<\/strong>Kh\u00f4ng \u0111\u01b0\u1ee3c tr\u1ed9n c\u00e1c k\u00fd hi\u1ec7u trong c\u00f9ng m\u1ed9t t\u00e0i li\u1ec7u. N\u1ebfu b\u1ea1n b\u1eaft \u0111\u1ea7u b\u1eb1ng Crow\u2019s Foot th\u00ec h\u00e3y k\u1ebft th\u00fac b\u1eb1ng Crow\u2019s Foot. Vi\u1ec7c chuy\u1ec3n \u0111\u1ed5i gi\u1eefa c\u00e1c k\u00fd hi\u1ec7u gi\u1eefa ch\u1eebng s\u1ebd g\u00e2y nh\u1ea7m l\u1eabn v\u1ec1 \u00fd ngh\u0129a c\u1ee7a t\u1eebng k\u00fd hi\u1ec7u c\u1ee5 th\u1ec3.<\/p>\n<\/li>\n- \n
Quy \u01b0\u1edbc \u0111\u1eb7t t\u00ean:<\/strong>\u0110\u1ea3m b\u1ea3o t\u00ean th\u1ef1c th\u1ec3 v\u00e0 thu\u1ed9c t\u00ednh tu\u00e2n theo quy \u01b0\u1edbc snake_case ho\u1eb7c camelCase nh\u1ea5t qu\u00e1n tr\u00ean to\u00e0n b\u1ed9 s\u01a1 \u0111\u1ed3. Nh\u1eefng t\u00ean m\u01a1 h\u1ed3 nh\u01b0 \u201cData\u201d hay \u201cInfo\u201d l\u00e0 d\u1ea5u hi\u1ec7u c\u1ea3nh b\u00e1o.<\/p>\n<\/li>\n- \n
Chu\u1ea9n h\u00f3a:<\/strong>\u00c1p d\u1ee5ng c\u00e1c quy t\u1eafc chu\u1ea9n h\u00f3a (t\u1ed1i \u0111a \u0111\u1ebfn 3NF ho\u1eb7c BCNF) tr\u01b0\u1edbc khi ho\u00e0n thi\u1ec7n s\u01a1 \u0111\u1ed3. M\u1ed9t s\u01a1 \u0111\u1ed3 ch\u01b0a \u0111\u01b0\u1ee3c chu\u1ea9n h\u00f3a s\u1ebd d\u1eabn \u0111\u1ebfn d\u01b0 th\u1eeba d\u1eef li\u1ec7u v\u00e0 c\u00e1c l\u1ed7i c\u1eadp nh\u1eadt.<\/p>\n<\/li>\n- \n
T\u00e0i li\u1ec7u r\u00e0ng bu\u1ed9c:<\/strong>Ghi r\u00f5 r\u00e0ng c\u00e1c r\u00e0ng bu\u1ed9c duy nh\u1ea5t v\u00e0 r\u00e0ng bu\u1ed9c ki\u1ec3m tra. C\u00e1c k\u00fd hi\u1ec7u tr\u1ef1c quan th\u1ec3 hi\u1ec7n m\u1ed1i quan h\u1ec7, nh\u01b0ng c\u00e1c ghi ch\u00fa v\u0103n b\u1ea3n th\u01b0\u1eddng l\u00e0m r\u00f5 c\u00e1c quy t\u1eafc kinh doanh.<\/p>\n<\/li>\n- \n
Ki\u1ec3m so\u00e1t phi\u00ean b\u1ea3n:<\/strong>Xem s\u01a1 \u0111\u1ed3 ER nh\u01b0 m\u00e3 ngu\u1ed3n. L\u01b0u tr\u1eef ch\u00fang trong h\u1ec7 th\u1ed1ng ki\u1ec3m so\u00e1t phi\u00ean b\u1ea3n c\u1ee7a b\u1ea1n. Nh\u1eefng thay \u0111\u1ed5i v\u00e0o c\u1ea5u tr\u00fac d\u1eef li\u1ec7u c\u1ea7n \u0111\u01b0\u1ee3c xem x\u00e9t k\u1ef9 nh\u01b0 c\u00e1c thay \u0111\u1ed5i m\u00e3 ngu\u1ed3n.<\/p>\n<\/li>\n<\/ul>\n\ud83d\udeab Nh\u1eefng sai l\u1ea7m ph\u1ed5 bi\u1ebfn c\u1ea7n tr\u00e1nh<\/h2>\n
Ngay c\u1ea3 nh\u1eefng ki\u1ebfn tr\u00fac s\u01b0 c\u00f3 kinh nghi\u1ec7m c\u0169ng m\u1eafc sai l\u1ea7m khi tr\u1ef1c quan h\u00f3a c\u1ea5u tr\u00fac d\u1eef li\u1ec7u. Nh\u1eadn th\u1ee9c \u0111\u01b0\u1ee3c nh\u1eefng l\u1ed7i ph\u1ed5 bi\u1ebfn n\u00e0y c\u00f3 th\u1ec3 ti\u1ebft ki\u1ec7m r\u1ea5t nhi\u1ec1u th\u1eddi gian trong qu\u00e1 tr\u00ecnh ph\u00e1t tri\u1ec3n.<\/p>\n
1. B\u1ecf qua kh\u1ea3 n\u0103ng null<\/h3>\n
M\u1ed9t \u0111\u01b0\u1eddng m\u1ed1i quan h\u1ec7 kh\u00f4ng c\u00f3 v\u00f2ng tr\u00f2n hay thanh ngang ng\u1ee5 \u00fd m\u1ed9t gi\u00e1 tr\u1ecb m\u1eb7c \u0111\u1ecbnh, t\u00f9y thu\u1ed9c v\u00e0o c\u00f4ng c\u1ee5. Lu\u00f4n ph\u1ea3i n\u00eau r\u00f5 r\u00e0ng n\u1ebfu kh\u00f3a ngo\u1ea1i c\u00f3 th\u1ec3 l\u00e0 null. Trong Crow\u2019s Foot, \u0111i\u1ec1u n\u00e0y l\u00e0 m\u1ed9t v\u00f2ng tr\u00f2n. Trong UML, \u0111\u00f3 l\u00e0 b\u1ed9i s\u1ed1 0..1. Vi\u1ec7c suy \u0111o\u00e1n l\u00e0 m\u1ed9t th\u00f3i quen nguy hi\u1ec3m.<\/p>\n
2. M\u00f4 h\u00ecnh h\u00f3a qu\u00e1 m\u1ee9c c\u00e1c m\u1ed1i quan h\u1ec7 tam ph\u00e2n<\/h3>\n
M\u1eb7c d\u00f9 k\u00fd hi\u1ec7u Chen x\u1eed l\u00fd t\u1ed1t c\u00e1c m\u1ed1i quan h\u1ec7 tam ph\u00e2n, nh\u01b0ng c\u00e1c c\u01a1 s\u1edf d\u1eef li\u1ec7u quan h\u1ec7 kh\u00f4ng h\u1ed7 tr\u1ee3 ch\u00fang m\u1ed9t c\u00e1ch t\u1ef1 nhi\u00ean. M\u1ed9t m\u1ed1i quan h\u1ec7 gi\u1eefa ba b\u1ea3ng th\u01b0\u1eddng c\u1ea7n \u0111\u01b0\u1ee3c chia nh\u1ecf th\u00e0nh c\u00e1c m\u1ed1i quan h\u1ec7 nh\u1ecb ph\u00e2n ho\u1eb7c m\u1ed9t th\u1ef1c th\u1ec3 li\u00ean k\u1ebft. Vi\u1ec7c m\u00f4 h\u00ecnh h\u00f3a m\u1ed9t li\u00ean k\u1ebft ba chi\u1ec1u tr\u1ef1c ti\u1ebfp c\u00f3 th\u1ec3 d\u1eabn \u0111\u1ebfn kh\u00f3 kh\u0103n trong tri\u1ec3n khai.<\/p>\n
3. Nh\u1ea7m l\u1eabn gi\u1eefa t\u00edch h\u1ee3p v\u00e0 k\u1ebft h\u1ee3p<\/h3>\n
Trong UML, s\u1ef1 kh\u00e1c bi\u1ec7t gi\u1eefa h\u00ecnh thoi r\u1ed7ng v\u00e0 h\u00ecnh thoi \u0111\u1ea7y l\u00e0 r\u1ea5t quan tr\u1ecdng. H\u00ecnh thoi r\u1ed7ng c\u00f3 ngh\u0129a l\u00e0 con c\u00f3 th\u1ec3 t\u1ed3n t\u1ea1i m\u00e0 kh\u00f4ng c\u1ea7n cha. H\u00ecnh thoi \u0111\u1ea7y c\u00f3 ngh\u0129a l\u00e0 kh\u00f4ng th\u1ec3. Vi\u1ec7c nh\u1ea7m l\u1eabn gi\u1eefa ch\u00fang c\u00f3 th\u1ec3 d\u1eabn \u0111\u1ebfn v\u1ea5n \u0111\u1ec1 d\u1eef li\u1ec7u b\u1ecb b\u1ecf r\u01a1i, khi c\u00e1c b\u1ea3n ghi con b\u1ecb x\u00f3a ho\u1eb7c l\u01b0u tr\u1eef sai c\u00e1ch.<\/p>\n
4. Ph\u1ee5 thu\u1ed9c v\u00f2ng l\u1eb7p<\/h3>\n
M\u1ed9t tham chi\u1ebfu v\u00f2ng x\u1ea3y ra khi B\u1ea3ng A tham chi\u1ebfu B\u1ea3ng B, v\u00e0 B\u1ea3ng B tham chi\u1ebfu B\u1ea3ng A. M\u1eb7c d\u00f9 \u0111\u00f4i khi h\u1ee3p l\u1ec7 (v\u00ed d\u1ee5: m\u1ed9t c\u1ea5u tr\u00fac ph\u00e2n c\u1ea5p), \u0111i\u1ec1u n\u00e0y l\u00e0m ph\u1ee9c t\u1ea1p qu\u00e1 tr\u00ecnh sao l\u01b0u v\u00e0 kh\u00f4i ph\u1ee5c. \u0110\u1ea3m b\u1ea3o s\u01a1 \u0111\u1ed3 r\u00f5 r\u00e0ng ch\u1ec9 ra h\u01b0\u1edbng c\u1ee7a m\u1ed1i ph\u1ee5 thu\u1ed9c \u0111\u1ec3 tr\u00e1nh l\u1ed7i th\u1ee9 t\u1ef1 t\u1ea1o.<\/p>\n
5. B\u1ecf qua x\u00f3a m\u1ec1m<\/h3>\n
C\u00e1c h\u1ec7 th\u1ed1ng hi\u1ec7n \u0111\u1ea1i th\u01b0\u1eddng y\u00eau c\u1ea7u x\u00f3a m\u1ec1m (\u0111\u00e1nh d\u1ea5u m\u1ed9t h\u00e0ng l\u00e0 kh\u00f4ng ho\u1ea1t \u0111\u1ed9ng thay v\u00ec x\u00f3a n\u00f3 \u0111i). M\u1ed9t s\u01a1 \u0111\u1ed3 n\u00ean ch\u1ec9 ra n\u01a1i \u0111\u1eb7t c\u1ed9t `deleted_at` ho\u1eb7c `is_active`. \u0110\u00e2y l\u00e0 m\u1ed9t thay \u0111\u1ed5i logic \u1ea3nh h\u01b0\u1edfng \u0111\u1ebfn l\u01b0\u1ee3c \u0111\u1ed3 v\u1eadt l\u00fd.<\/p>\n
\ud83d\udd04 Chuy\u1ec3n \u0111\u1ed5i gi\u1eefa c\u00e1c k\u00fd hi\u1ec7u<\/h2>\n
Th\u01b0\u1eddng xuy\u00ean x\u1ea3y ra khi m\u1ed9t d\u1ef1 \u00e1n b\u1eaft \u0111\u1ea7u b\u1eb1ng Chen \u0111\u1ec3 l\u1eadp k\u1ebf ho\u1ea1ch c\u1ea5p cao v\u00e0 k\u1ebft th\u00fac b\u1eb1ng Crow\u2019s Foot \u0111\u1ec3 tri\u1ec3n khai. Hi\u1ec3u r\u00f5 s\u1ef1 \u00e1nh x\u1ea1 gi\u1eefa ch\u00fang \u0111\u1ea3m b\u1ea3o t\u00ednh to\u00e0n v\u1eb9n d\u1eef li\u1ec7u \u0111\u01b0\u1ee3c duy tr\u00ec trong qu\u00e1 tr\u00ecnh chuy\u1ec3n \u0111\u1ed5i.<\/p>\n
\n- \n
Chen sang Crow\u2019s Foot:<\/strong>Chuy\u1ec3n h\u00ecnh thoi th\u00e0nh \u0111\u01b0\u1eddng th\u1eb3ng. Chuy\u1ec3n c\u00e1c nh\u00e3n (1, N) th\u00e0nh k\u00fd hi\u1ec7u ch\u00e2n chim. Th\u00eam c\u00e1c thanh\/\u0111\u01b0\u1eddng tr\u00f2n m\u00f4 t\u1ea3 d\u1ef1a tr\u00ean c\u00e1c quy t\u1eafc kinh doanh ng\u1ea7m \u0111\u1ecbnh t\u1eeb thi\u1ebft k\u1ebf ban \u0111\u1ea7u.<\/p>\n<\/li>\n- \n
UML sang Crow\u2019s Foot:<\/strong>Lo\u1ea1i b\u1ecf c\u00e1c thao t\u00e1c l\u1edbp (ph\u01b0\u01a1ng th\u1ee9c). \u0110\u01a1n gi\u1ea3n h\u00f3a c\u00e1c \u0111\u01b0\u1eddng bi\u1ec3u di\u1ec5n t\u00edch h\u1ee3p\/th\u00e0nh ph\u1ea7n th\u00e0nh kh\u00f3a ngo\u1ea1i ti\u00eau chu\u1ea9n. \u0110i\u1ec1u ch\u1ec9nh k\u00fd hi\u1ec7u b\u1ed9i s\u1ed1 \u0111\u1ec3 ph\u00f9 h\u1ee3p v\u1edbi k\u00fd hi\u1ec7u Crow\u2019s Foot.<\/p>\n<\/li>\n- \n
Crow\u2019s Foot sang UML:<\/strong>Th\u00eam c\u1ea5u tr\u00fac h\u1ed9p l\u1edbp. \u00c1nh x\u1ea1 c\u00e1c \u0111\u01b0\u1eddng quan h\u1ec7 th\u00e0nh m\u0169i t\u00ean li\u00ean k\u1ebft. X\u00e1c \u0111\u1ecbnh m\u1ed1i quan h\u1ec7 l\u00e0 t\u00edch h\u1ee3p hay th\u00e0nh ph\u1ea7n d\u1ef1a tr\u00ean v\u00f2ng \u0111\u1eddi d\u1eef li\u1ec7u.<\/p>\n<\/li>\n<\/ul>\n\ud83d\udcdd Nh\u1eefng suy ngh\u0129 cu\u1ed1i c\u00f9ng v\u1ec1 m\u00f4 h\u00ecnh h\u00f3a d\u1eef li\u1ec7u<\/h2>\n
Vi\u1ec7c l\u1ef1a ch\u1ecdn k\u00fd hi\u1ec7u kh\u00f4ng ch\u1ec9 mang t\u00ednh th\u1ea9m m\u1ef9; n\u00f3 l\u00e0 m\u1ed9t c\u00f4ng c\u1ee5 giao ti\u1ebfp quy\u1ebft \u0111\u1ecbnh c\u00e1ch hi\u1ec3u v\u00e0 x\u00e2y d\u1ef1ng c\u01a1 s\u1edf d\u1eef li\u1ec7u. Chen cung c\u1ea5p s\u1ef1 r\u00f5 r\u00e0ng v\u1ec1 kh\u00e1i ni\u1ec7m, Crow\u2019s Foot mang l\u1ea1i \u0111\u1ed9 ch\u00ednh x\u00e1c quan h\u1ec7, c\u00f2n UML mang \u0111\u1ebfn s\u1ef1 t\u00edch h\u1ee3p h\u01b0\u1edbng \u0111\u1ed1i t\u01b0\u1ee3ng.<\/p>\n
B\u1eb1ng c\u00e1ch ch\u1ecdn k\u00fd hi\u1ec7u ph\u00f9 h\u1ee3p v\u1edbi chuy\u00ean m\u00f4n c\u1ee7a \u0111\u1ed9i ng\u0169 v\u00e0 ki\u1ebfn tr\u00fac h\u1ec7 th\u1ed1ng c\u1ee7a b\u1ea1n, b\u1ea1n s\u1ebd gi\u1ea3m thi\u1ec3u r\u1ee7i ro hi\u1ec3u l\u1ea7m. M\u1ed9t l\u01b0\u1ee3c \u0111\u1ed3 \u0111\u01b0\u1ee3c t\u00e0i li\u1ec7u h\u00f3a t\u1ed1t \u0111\u00f3ng vai tr\u00f2 nh\u01b0 m\u1ed9t h\u1ee3p \u0111\u1ed3ng gi\u1eefa d\u1eef li\u1ec7u v\u00e0 \u1ee9ng d\u1ee5ng. D\u00f9 b\u1ea1n \u0111ang v\u1ebd h\u00ecnh thoi, ch\u00e2n chim hay h\u1ed9p l\u1edbp, m\u1ee5c ti\u00eau v\u1eabn nh\u01b0 nhau: t\u1ea1o n\u00ean n\u1ec1n t\u1ea3ng \u1ed5n \u0111\u1ecbnh cho d\u1eef li\u1ec7u c\u1ee7a b\u1ea1n.<\/p>\n
D\u00e0nh th\u1eddi gian cho giai \u0111o\u1ea1n m\u00f4 h\u00ecnh h\u00f3a. Chi ph\u00ed thay \u0111\u1ed5i m\u1ed9t s\u01a1 \u0111\u1ed3 l\u00e0 r\u1ea5t nh\u1ecf so v\u1edbi chi ph\u00ed t\u00e1i c\u1ea5u tr\u00fac c\u01a1 s\u1edf d\u1eef li\u1ec7u \u0111\u00e3 tri\u1ec3n khai. Ch\u1ecdn ng\u00f4n ng\u1eef tr\u1ef1c quan m\u1ed9t c\u00e1ch kh\u00f4n kh\u00e9o, v\u00e0 \u0111\u1ea3m b\u1ea3o m\u1ecdi b\u00ean li\u00ean quan \u0111\u1ec1u n\u00f3i c\u00f9ng m\u1ed9t th\u1ee9 ti\u1ebfng.<\/p>\n","protected":false},"excerpt":{"rendered":"
Thi\u1ebft k\u1ebf m\u1ed9t l\u01b0\u1ee3c \u0111\u1ed3 c\u01a1 s\u1edf d\u1eef li\u1ec7u m\u1ea1nh m\u1ebd \u0111\u00f2i h\u1ecfi h\u01a1n c\u1ea3 vi\u1ec7c bi\u1ebft b\u1ea3ng n\u00e0o ch\u1ee9a d\u1eef li\u1ec7u g\u00ec. N\u00f3 \u0111\u00f2i h\u1ecfi m\u1ed9t ng\u00f4n ng\u1eef r\u00f5…<\/p>\n","protected":false},"author":1,"featured_media":76,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_yoast_wpseo_title":"C\u00e1c k\u00fd hi\u1ec7u s\u01a1 \u0111\u1ed3 ER: So s\u00e1nh Crow\u2019s Foot, UML, Chen","_yoast_wpseo_metadesc":"So s\u00e1nh c\u00e1c k\u00fd hi\u1ec7u s\u01a1 \u0111\u1ed3 ER nh\u01b0 Crow\u2019s Foot, UML v\u00e0 Chen. H\u1ecdc c\u00e1ch s\u1eed d\u1ee5ng t\u1eebng lo\u1ea1i ph\u00f9 h\u1ee3p v\u1edbi thi\u1ebft k\u1ebf c\u01a1 s\u1edf d\u1eef li\u1ec7u, m\u00f4 h\u00ecnh h\u00f3a l\u01b0\u1ee3c \u0111\u1ed3 v\u00e0 kh\u1ea3 n\u0103ng t\u01b0\u01a1ng th\u00edch v\u1edbi stack.","inline_featured_image":false,"fifu_image_url":"","fifu_image_alt":"","footnotes":""},"categories":[6],"tags":[10,11],"class_list":["post-75","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-erd","tag-academic","tag-erd"],"yoast_head":"\n
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Th\u1ef1c th\u1ec3:<\/strong>\u0110\u01b0\u1ee3c bi\u1ec3u di\u1ec5n b\u1eb1ng h\u00ecnh ch\u1eef nh\u1eadt. Ch\u00fang ch\u1ee9a kh\u00f3a ch\u00ednh v\u00e0 c\u00e1c thu\u1ed9c t\u00ednh.<\/p>\n<\/li>\n Thu\u1ed9c t\u00ednh:<\/strong>\u0110\u01b0\u1ee3c bi\u1ec3u di\u1ec5n b\u1eb1ng h\u00ecnh elip k\u1ebft n\u1ed1i v\u1edbi h\u00ecnh ch\u1eef nh\u1eadt th\u1ef1c th\u1ec3. Kh\u00f3a ch\u00ednh th\u01b0\u1eddng \u0111\u01b0\u1ee3c g\u1ea1ch ch\u00e2n.<\/p>\n<\/li>\n M\u1ed1i quan h\u1ec7:<\/strong>\u0110\u01b0\u1ee3c bi\u1ec3u di\u1ec5n b\u1eb1ng h\u00ecnh thoi k\u1ebft n\u1ed1i hai th\u1ef1c th\u1ec3.<\/p>\n<\/li>\n S\u1ed1 l\u01b0\u1ee3ng:<\/strong>\u0110\u01b0\u1ee3c bi\u1ec3u th\u1ecb b\u1eb1ng c\u00e1c \u0111\u01b0\u1eddng n\u1ed1i t\u1eeb h\u00ecnh thoi \u0111\u1ebfn c\u00e1c th\u1ef1c th\u1ec3, th\u01b0\u1eddng \u0111\u01b0\u1ee3c \u0111\u00e1nh nh\u00e3n b\u1eb1ng s\u1ed1 ho\u1eb7c ch\u1eef c\u00e1i (1, N, M).<\/p>\n<\/li>\n Th\u1ef1c th\u1ec3 y\u1ebfu:<\/strong>\u0110\u01b0\u1ee3c th\u1ec3 hi\u1ec7n b\u1eb1ng h\u00ecnh ch\u1eef nh\u1eadt k\u00e9p, cho th\u1ea5y s\u1ef1 ph\u1ee5 thu\u1ed9c v\u00e0o th\u1ef1c th\u1ec3 cha \u0111\u1ec3 t\u1ed3n t\u1ea1i.<\/p>\n<\/li>\n M\u1ed1i quan h\u1ec7 x\u00e1c \u0111\u1ecbnh:<\/strong>\u0110\u01b0\u1ee3c th\u1ec3 hi\u1ec7n b\u1eb1ng c\u00e1c \u0111\u01b0\u1eddng k\u00e9p n\u1ed1i th\u1ef1c th\u1ec3 y\u1ebfu v\u1edbi cha c\u1ee7a n\u00f3.<\/p>\n<\/li>\n<\/ul>\n K\u00fd hi\u1ec7u Chen t\u1ecf ra v\u01b0\u1ee3t tr\u1ed9i trong c\u00e1c t\u00ecnh hu\u1ed1ng c\u1ea7n gi\u1ea3i th\u00edch thi\u1ebft k\u1ebf c\u01a1 s\u1edf d\u1eef li\u1ec7u cho nh\u1eefng ng\u01b0\u1eddi kh\u00f4ng vi\u1ebft SQL. Vi\u1ec7c s\u1eed d\u1ee5ng h\u00ecnh elip v\u00e0 h\u00ecnh thoi gi\u00fap ph\u00e2n bi\u1ec7t r\u00f5 r\u00e0ng gi\u1eefa m\u1ed9t th\u1ef1c th\u1ec3 (c\u00e1i g\u00ec \u0111\u00f3) v\u00e0 m\u1ed9t m\u1ed1i quan h\u1ec7 (m\u1ed9t h\u00e0nh \u0111\u1ed9ng).<\/p>\n T\u00e0i li\u1ec7u h\u1ec7 th\u1ed1ng c\u0169:<\/strong>Nhi\u1ec1u h\u1ec7 th\u1ed1ng c\u0169 \u0111\u01b0\u1ee3c thi\u1ebft k\u1ebf theo chu\u1ea9n n\u00e0y. Vi\u1ec7c duy tr\u00ec s\u1ef1 nh\u1ea5t qu\u00e1n v\u1edbi c\u00e1c s\u01a1 \u0111\u1ed3 l\u1ecbch s\u1eed l\u00e0 r\u1ea5t quan tr\u1ecdng.<\/p>\n<\/li>\n Ph\u00e2n t\u00edch kinh doanh c\u1ea5p cao:<\/strong>Khi th\u1ea3o lu\u1eadn v\u1ec1 y\u00eau c\u1ea7u d\u1eef li\u1ec7u v\u1edbi c\u00e1c qu\u1ea3n l\u00fd s\u1ea3n ph\u1ea9m, h\u00ecnh thoi r\u00f5 r\u00e0ng cho th\u1ea5y m\u1ed1i li\u00ean k\u1ebft gi\u1eefa hai kh\u00e1i ni\u1ec7m kinh doanh.<\/p>\n<\/li>\n B\u1ed1i c\u1ea3nh h\u1ecdc thu\u1eadt v\u00e0 l\u00fd thuy\u1ebft:<\/strong>Ch\u01b0\u01a1ng tr\u00ecnh h\u1ecdc ng\u00e0nh khoa h\u1ecdc m\u00e1y t\u00ednh th\u01b0\u1eddng d\u1ea1y k\u00fd hi\u1ec7u Chen tr\u01b0\u1edbc \u0111\u1ec3 x\u00e2y d\u1ef1ng n\u1ec1n t\u1ea3ng l\u00fd thuy\u1ebft tr\u01b0\u1edbc khi chuy\u1ec3n sang c\u00e1c phong c\u00e1ch c\u1ee5 th\u1ec3 h\u00f3a tri\u1ec3n khai.<\/p>\n<\/li>\n<\/ul>\n Tuy nhi\u00ean, k\u00fd hi\u1ec7u n\u00e0y c\u00f3 th\u1ec3 tr\u1edf n\u00ean r\u1ed1i r\u1eafm khi c\u00e1c m\u1ed1i quan h\u1ec7 ph\u1ee9c t\u1ea1p. C\u00e1c m\u1ed1i quan h\u1ec7 tam ph\u00e2n (m\u1ed1i quan h\u1ec7 gi\u1eefa ba th\u1ef1c th\u1ec3) d\u1ec5 h\u00ecnh dung trong Chen nh\u01b0ng l\u1ea1i kh\u00f3 chuy\u1ec3n \u0111\u1ed5i tr\u1ef1c ti\u1ebfp sang c\u00e1c r\u00e0ng bu\u1ed9c c\u01a1 s\u1edf d\u1eef li\u1ec7u quan h\u1ec7 m\u00e0 kh\u00f4ng c\u1ea7n di\u1ec5n gi\u1ea3i th\u00eam.<\/p>\n C\u0169ng \u0111\u01b0\u1ee3c bi\u1ebft \u0111\u1ebfn v\u1edbi t\u00ean g\u1ecdi k\u00fd hi\u1ec7u IE (K\u1ef9 thu\u1eadt th\u00f4ng tin), k\u00fd hi\u1ec7u ch\u00e2n chim tr\u1edf th\u00e0nh chu\u1ea9n ng\u1ea7m \u0111\u1ecbnh cho thi\u1ebft k\u1ebf c\u01a1 s\u1edf d\u1eef li\u1ec7u quan h\u1ec7 v\u00e0o cu\u1ed1i th\u1ebf k\u1ef7 20. N\u00f3 r\u1ea5t th\u1ef1c ti\u1ec5n \u0111\u1ed1i v\u1edbi c\u00e1c qu\u1ea3n tr\u1ecb vi\u00ean c\u01a1 s\u1edf d\u1eef li\u1ec7u v\u00e0 k\u1ef9 s\u01b0 backend. T\u00ean g\u1ecdi xu\u1ea5t ph\u00e1t t\u1eeb h\u00ecnh d\u1ea1ng d\u00f9ng \u0111\u1ec3 bi\u1ec3u di\u1ec5n ph\u00eda “nhi\u1ec1u” c\u1ee7a m\u1ed9t m\u1ed1i quan h\u1ec7, tr\u00f4ng gi\u1ed1ng nh\u01b0 ch\u00e2n c\u1ee7a m\u1ed9t con chim c\u00fat.<\/p>\n C\u00e1c th\u1ef1c th\u1ec3:<\/strong>\u0110\u01b0\u1ee3c bi\u1ec3u di\u1ec5n b\u1eb1ng c\u00e1c h\u00ecnh ch\u1eef nh\u1eadt (th\u01b0\u1eddng ch\u1ec9 l\u00e0 t\u00ean b\u1ea3ng trong c\u00e1c c\u00f4ng c\u1ee5 hi\u1ec7n \u0111\u1ea1i).<\/p>\n<\/li>\n C\u00e1c m\u1ed1i quan h\u1ec7:<\/strong>\u0110\u01b0\u1ee3c bi\u1ec3u di\u1ec5n b\u1eb1ng c\u00e1c \u0111\u01b0\u1eddng th\u1eb3ng n\u1ed1i c\u00e1c b\u1ea3ng v\u1edbi nhau.<\/p>\n<\/li>\n S\u1ed1 l\u01b0\u1ee3ng (k\u00fd hi\u1ec7u \u201cCh\u00e2n qu\u1ea1\u201d):<\/strong>M\u1ed9t k\u00fd hi\u1ec7u ba nh\u00e1nh (gi\u1ed1ng nh\u01b0 ch\u00e2n c\u1ee7a con qu\u1ea1) cho bi\u1ebft ph\u00eda \u201cnhi\u1ec1u\u201d trong m\u1ed1i quan h\u1ec7.<\/p>\n<\/li>\n T\u00ednh ch\u1ea5t tham gia:<\/strong>M\u1ed9t thanh ngang (|) cho bi\u1ebft tham gia b\u1eaft bu\u1ed9c (ph\u1ea3i t\u1ed3n t\u1ea1i), trong khi m\u1ed9t v\u00f2ng tr\u00f2n (o) cho bi\u1ebft tham gia t\u00f9y ch\u1ecdn (c\u00f3 th\u1ec3 l\u00e0 null).<\/p>\n<\/li>\n Kh\u00f3a ch\u00ednh:<\/strong>Th\u01b0\u1eddng \u0111\u01b0\u1ee3c \u0111\u00e1nh d\u1ea5u b\u1eb1ng bi\u1ec3u t\u01b0\u1ee3ng ch\u00eca kh\u00f3a ho\u1eb7c ch\u00fa th\u00edch v\u0103n b\u1ea3n c\u1ee5 th\u1ec3 b\u00ean c\u1ea1nh thu\u1ed9c t\u00ednh.<\/p>\n<\/li>\n<\/ul>\n K\u00fd hi\u1ec7u ch\u00e2n qu\u1ea1 \u0111\u01b0\u1ee3c t\u1ed1i \u01b0u h\u00f3a \u0111\u1ec3 \u00e1nh x\u1ea1 tr\u1ef1c ti\u1ebfp sang c\u00e1c l\u1ec7nh DDL SQL. N\u1ebfu b\u1ea1n \u0111ang vi\u1ebft l\u01b0\u1ee3c \u0111\u1ed3, \u0111\u00e2y c\u00f3 l\u1ebd l\u00e0 ng\u00f4n ng\u1eef tr\u1ef1c quan b\u1ea1n \u0111ang s\u1eed d\u1ee5ng.<\/p>\n Thi\u1ebft k\u1ebf c\u01a1 s\u1edf d\u1eef li\u1ec7u quan h\u1ec7:<\/strong>N\u00f3 \u00e1nh x\u1ea1 r\u00f5 r\u00e0ng sang c\u00e1c kh\u00f3a ngo\u1ea1i v\u00e0 kh\u00f3a ch\u00ednh trong c\u00e1c c\u01a1 s\u1edf d\u1eef li\u1ec7u SQL nh\u01b0 PostgreSQL, MySQL ho\u1eb7c SQL Server.<\/p>\n<\/li>\n T\u00e0i li\u1ec7u l\u01b0\u1ee3c \u0111\u1ed3:<\/strong>N\u00f3 l\u00e0 ti\u00eau chu\u1ea9n ng\u00e0nh cho t\u00e0i li\u1ec7u k\u1ef9 thu\u1eadt trong c\u00e1c nh\u00f3m ph\u00e1t tri\u1ec3n.<\/p>\n<\/li>\n R\u00f5 r\u00e0ng v\u1ec1 t\u00ednh to\u00e0n v\u1eb9n d\u1eef li\u1ec7u:<\/strong>Vi\u1ec7c s\u1eed d\u1ee5ng thanh ngang v\u00e0 v\u00f2ng tr\u00f2n x\u00e1c \u0111\u1ecbnh r\u00f5 r\u00e0ng c\u00e1c r\u00e0ng bu\u1ed9c kh\u1ea3 n\u0103ng null, \u0111i\u1ec1u n\u00e0y r\u1ea5t quan tr\u1ecdng \u0111\u1ed1i v\u1edbi logic ph\u00eda backend.<\/p>\n<\/li>\n<\/ul>\n K\u00fd hi\u1ec7u n\u00e0y \u00edt tr\u1eebu t\u01b0\u1ee3ng h\u01a1n Chen. N\u00f3 gi\u1ea3 \u0111\u1ecbnh ng\u01b0\u1eddi xem hi\u1ec3u kh\u00e1i ni\u1ec7m v\u1ec1 b\u1ea3ng v\u00e0 kh\u00f3a ngo\u1ea1i. \u0110i\u1ec1u n\u00e0y khi\u1ebfn n\u00f3 \u00edt ph\u00f9 h\u1ee3p cho c\u00e1c cu\u1ed9c h\u1ecdp kinh doanh c\u1ea5p cao nh\u01b0ng l\u1ea1i l\u00fd t\u01b0\u1edfng cho l\u1eadp k\u1ebf ho\u1ea1ch sprint k\u1ef9 thu\u1eadt.<\/p>\n Ng\u00f4n ng\u1eef m\u00f4 h\u00ecnh h\u00f3a th\u1ed1ng nh\u1ea5t (UML) \u0111\u01b0\u1ee3c ph\u00e1t tri\u1ec3n nh\u1eb1m chu\u1ea9n h\u00f3a thi\u1ebft k\u1ebf ph\u1ea7n m\u1ec1m tr\u00ean nhi\u1ec1u m\u00f4 h\u00ecnh kh\u00e1c nhau. M\u1eb7c d\u00f9 UML bao g\u1ed3m nhi\u1ec1u lo\u1ea1i s\u01a1 \u0111\u1ed3, s\u01a1 \u0111\u1ed3 l\u1edbp l\u00e0 lo\u1ea1i th\u01b0\u1eddng \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng nh\u1ea5t \u0111\u1ec3 m\u00f4 h\u00ecnh h\u00f3a c\u01a1 s\u1edf d\u1eef li\u1ec7u trong b\u1ed1i c\u1ea3nh h\u01b0\u1edbng \u0111\u1ed1i t\u01b0\u1ee3ng. N\u00f3 t\u1ea1o ra s\u1ef1 li\u00ean k\u1ebft gi\u1eefa c\u1ea5u tr\u00fac m\u00e3 ngu\u1ed3n v\u00e0 c\u1ea5u tr\u00fac d\u1eef li\u1ec7u.<\/p>\n L\u1edbp:<\/strong>H\u00ecnh ch\u1eef nh\u1eadt \u0111\u01b0\u1ee3c chia th\u00e0nh ba ph\u1ea7n: T\u00ean, Thu\u1ed9c t\u00ednh v\u00e0 Thao t\u00e1c (ph\u01b0\u01a1ng th\u1ee9c).<\/p>\n<\/li>\n C\u00e1c m\u1ed1i quan h\u1ec7:<\/strong>C\u00e1c \u0111\u01b0\u1eddng n\u1ed1i c\u00e1c l\u1edbp v\u1edbi \u0111\u1ea7u m\u0169i t\u00ean c\u1ee5 th\u1ec3 \u0111\u1ec3 ch\u1ec9 h\u01b0\u1edbng v\u00e0 lo\u1ea1i m\u1ed1i quan h\u1ec7.<\/p>\n<\/li>\n Li\u00ean k\u1ebft:<\/strong>M\u1ed9t \u0111\u01b0\u1eddng \u0111\u01a1n gi\u1ea3n. Cho bi\u1ebft m\u1ed1i quan h\u1ec7 t\u1ed3n t\u1ea1i.<\/p>\n<\/li>\n T\u1ed5 h\u1ee3p:<\/strong>M\u1ed9t h\u00ecnh kim c\u01b0\u01a1ng r\u1ed7ng \u1edf m\u1ed9t \u0111\u1ea7u. Cho bi\u1ebft m\u1ed1i quan h\u1ec7 \u201cto\u00e0n th\u1ec3-ph\u1ea7n\u201d, trong \u0111\u00f3 c\u00e1c ph\u1ea7n c\u00f3 th\u1ec3 t\u1ed3n t\u1ea1i \u0111\u1ed9c l\u1eadp.<\/p>\n<\/li>\n Th\u00e0nh ph\u1ea7n:<\/strong>M\u1ed9t h\u00ecnh thoi \u0111\u1ea7y. Ch\u1ec9 ra m\u1ed1i quan h\u1ec7 ph\u1ee5 thu\u1ed9c v\u00f2ng \u0111\u1eddi nghi\u00eam ng\u1eb7t; n\u1ebfu to\u00e0n b\u1ed9 b\u1ecb h\u1ee7y, c\u00e1c b\u1ed9 ph\u1eadn c\u0169ng s\u1ebd b\u1ecb h\u1ee7y.<\/p>\n<\/li>\n \u0110a d\u1ea1ng:<\/strong>C\u00e1c s\u1ed1 \u0111\u01b0\u1ee3c \u0111\u1eb7t g\u1ea7n hai \u0111\u1ea7u c\u1ee7a \u0111\u01b0\u1eddng n\u1ed1i (v\u00ed d\u1ee5: 0..1, 1..*, 0..*). V\u1ec1 m\u1eb7t ch\u1ee9c n\u0103ng t\u01b0\u01a1ng t\u1ef1 nh\u01b0 k\u00fd hi\u1ec7u Crow\u2019s Foot nh\u01b0ng s\u1eed d\u1ee5ng k\u00fd hi\u1ec7u to\u00e1n h\u1ecdc.<\/p>\n<\/li>\n<\/ul>\n S\u01a1 \u0111\u1ed3 l\u1edbp UML l\u00e0 thi\u1ebft y\u1ebfu khi c\u01a1 s\u1edf d\u1eef li\u1ec7u kh\u00f4ng ph\u1ea3i l\u00e0 \u0111i\u1ec3m t\u1eadp trung duy nh\u1ea5t. Ch\u00fang l\u00e0 l\u1edbp k\u1ebft n\u1ed1i gi\u1eefa m\u00e3 ph\u00eda backend v\u00e0 l\u1edbp l\u01b0u tr\u1eef b\u1ec1n v\u1eefng.<\/p>\n \u00c1nh x\u1ea1 ORM:<\/strong>C\u00e1c tr\u00ecnh \u00e1nh x\u1ea1 \u0111\u1ed1i t\u01b0\u1ee3ng-quan h\u1ec7 (ORMs) ph\u1ee5 thu\u1ed9c r\u1ea5t nhi\u1ec1u v\u00e0o c\u00e1c m\u1ed1i quan h\u1ec7 ki\u1ec3u UML \u0111\u1ec3 hi\u1ec3u c\u00e1ch \u00e1nh x\u1ea1 c\u00e1c l\u1edbp v\u00e0o b\u1ea3ng.<\/p>\n<\/li>\n Ki\u1ebfn tr\u00fac Full-Stack:<\/strong>Khi c\u00e1c \u0111\u1ed9i ng\u0169 frontend, backend v\u00e0 c\u01a1 s\u1edf d\u1eef li\u1ec7u c\u1ea7n th\u1ed1ng nh\u1ea5t v\u1ec1 c\u1ea5u tr\u00fac d\u1eef li\u1ec7u, UML cung c\u1ea5p m\u1ed9t t\u1eeb v\u1ef1ng chung.<\/p>\n<\/li>\n C\u00e1c m\u1ed1i quan h\u1ec7 ph\u1ee9c t\u1ea1p:<\/strong>UML x\u1eed l\u00fd k\u1ebf th\u1eeba, kh\u00e1i qu\u00e1t h\u00f3a v\u00e0 tri\u1ec3n khai giao di\u1ec7n t\u1ed1t h\u01a1n so v\u1edbi c\u00e1c k\u00fd hi\u1ec7u thu\u1ea7n t\u00fay d\u1ef1a tr\u00ean quan h\u1ec7.<\/p>\n<\/li>\n<\/ul>\n Nh\u01b0\u1ee3c \u0111i\u1ec3m l\u00e0 s\u1ef1 r\u01b0\u1eddm r\u00e0. M\u1ed9t m\u1ed1i quan h\u1ec7 b\u1ea3ng \u0111\u01a1n gi\u1ea3n trong k\u00fd hi\u1ec7u Crow\u2019s Foot c\u00f3 th\u1ec3 y\u00eau c\u1ea7u m\u1ed9t \u0111\u1ecbnh ngh\u0129a l\u1edbp ph\u1ee9c t\u1ea1p trong UML, bao g\u1ed3m c\u00e1c ph\u01b0\u01a1ng th\u1ee9c v\u00e0 thu\u1ed9c t\u00ednh kh\u00f4ng li\u00ean quan \u0111\u1ebfn c\u01a1 s\u1edf d\u1eef li\u1ec7u. \u0110i\u1ec1u n\u00e0y c\u00f3 th\u1ec3 d\u1eabn \u0111\u1ebfn nh\u1ea7m l\u1eabn n\u1ebfu s\u01a1 \u0111\u1ed3 \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng ch\u1ec9 \u0111\u1ec3 sinh l\u01b0\u1ee3c \u0111\u1ed3.<\/p>\n \u0110\u1ec3 d\u1ec5 d\u00e0ng \u0111\u01b0a ra quy\u1ebft \u0111\u1ecbnh h\u01a1n, \u0111\u00e2y l\u00e0 ph\u00e2n t\u00edch c\u00e1ch c\u00e1c k\u00fd hi\u1ec7u n\u00e0y x\u1eed l\u00fd c\u00e1c t\u00ecnh hu\u1ed1ng m\u00f4 h\u00ecnh h\u00f3a c\u1ee5 th\u1ec3.<\/p>\n T\u00ednh n\u0103ng<\/p>\n<\/th>\n K\u00fd hi\u1ec7u Chen<\/p>\n<\/th>\n K\u00fd hi\u1ec7u Crow\u2019s Foot<\/p>\n<\/th>\n S\u01a1 \u0111\u1ed3 l\u1edbp UML<\/p>\n<\/th>\n<\/tr>\n \u0110\u1ed1i t\u01b0\u1ee3ng ch\u00ednh<\/strong><\/p>\n<\/td>\n Nh\u00e0 ph\u00e2n t\u00edch kinh doanh, h\u1ecdc gi\u1ea3<\/p>\n<\/td>\n DBAs, K\u1ef9 s\u01b0 backend<\/p>\n<\/td>\n L\u1eadp tr\u00ecnh vi\u00ean full-stack, Ki\u1ebfn tr\u00fac s\u01b0<\/p>\n<\/td>\n<\/tr>\n Bi\u1ec3u di\u1ec5n th\u1ef1c th\u1ec3<\/strong><\/p>\n<\/td>\n H\u00ecnh ch\u1eef nh\u1eadt<\/p>\n<\/td>\n H\u00ecnh ch\u1eef nh\u1eadt (B\u1ea3ng)<\/p>\n<\/td>\n H\u1ed9p l\u1edbp (T\u00ean\/Thu\u1ed9c t\u00ednh\/Ph\u01b0\u01a1ng th\u1ee9c)<\/p>\n<\/td>\n<\/tr>\n Bi\u1ec3u di\u1ec5n m\u1ed1i quan h\u1ec7<\/strong><\/p>\n<\/td>\n H\u00ecnh thoi<\/p>\n<\/td>\n \u0110\u01b0\u1eddng n\u1ed1i v\u1edbi k\u00fd hi\u1ec7u<\/p>\n<\/td>\n \u0110\u01b0\u1eddng v\u1edbi \u0111\u1ea7u m\u0169i t\u00ean\/ h\u00ecnh thoi<\/p>\n<\/td>\n<\/tr>\n K\u00fd hi\u1ec7u cardinality<\/strong><\/p>\n<\/td>\n Nh\u00e3n (1, N, M)<\/p>\n<\/td>\n Crow\u2019s Foot + Thanh\/ H\u00ecnh tr\u00f2n<\/p>\n<\/td>\n To\u00e1n h\u1ecdc (0..1, *)<\/p>\n<\/td>\n<\/tr>\n Ch\u1ec9 th\u1ecb kh\u1ea3 n\u0103ng null<\/strong><\/p>\n<\/td>\n Ng\u1ea7m \u0111\u1ecbnh ho\u1eb7c v\u0103n b\u1ea3n<\/p>\n<\/td>\n R\u00f5 r\u00e0ng (H\u00ecnh tr\u00f2n = T\u00f9y ch\u1ecdn)<\/p>\n<\/td>\n R\u00f5 r\u00e0ng (B\u1ed9i s\u1ed1)<\/p>\n<\/td>\n<\/tr>\n T\u1ed1t nh\u1ea5t cho<\/strong><\/p>\n<\/td>\n M\u00f4 h\u00ecnh kh\u00e1i ni\u1ec7m<\/p>\n<\/td>\n M\u00f4 h\u00ecnh logic\/ v\u1eadt l\u00fd<\/p>\n<\/td>\n M\u00f4 h\u00ecnh tri\u1ec3n khai<\/p>\n<\/td>\n<\/tr>\n \u0110\u1ed9 ph\u1ee9c t\u1ea1p<\/strong><\/p>\n<\/td>\n Cao \u0111\u1ed1i v\u1edbi c\u00e1c li\u00ean k\u1ebft tam ph\u00e2n<\/p>\n<\/td>\n Trung b\u00ecnh<\/p>\n<\/td>\n Cao \u0111\u1ed1i v\u1edbi k\u1ebf th\u1eeba<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n Kh\u00f4ng c\u00f3 k\u00fd hi\u1ec7u ‘t\u1ed1t nh\u1ea5t’ duy nh\u1ea5t. L\u1ef1a ch\u1ecdn \u0111\u00fang ph\u1ee5 thu\u1ed9c v\u00e0o giai \u0111o\u1ea1n v\u00f2ng \u0111\u1eddi c\u1ee7a d\u1ef1 \u00e1n v\u00e0 c\u00e1c c\u00f4ng ngh\u1ec7 tham gia.<\/p>\n N\u1ebfu b\u1ea1n \u0111ang thi\u1ebft k\u1ebf m\u1ed9t kho d\u1eef li\u1ec7u ho\u1eb7c h\u1ec7 th\u1ed1ng giao d\u1ecbch m\u00e0 tr\u1ecdng t\u00e2m ho\u00e0n to\u00e0n l\u00e0 c\u00e1c b\u1ea3ng SQL v\u00e0 hi\u1ec7u su\u1ea5t truy v\u1ea5n, Crow\u2019s Foot l\u00e0 l\u1ef1a ch\u1ecdn hi\u1ec7u qu\u1ea3 nh\u1ea5t. N\u00f3 gi\u1ea3m thi\u1ec3u t\u1ea3i nh\u1eadn th\u1ee9c v\u1ec1 c\u00e1c kh\u00e1i ni\u1ec7m \u0111\u1ed1i t\u01b0\u1ee3ng v\u00e0 t\u1ed1i \u0111a h\u00f3a \u0111\u1ed9 r\u00f5 r\u00e0ng v\u1ec1 r\u00e0ng bu\u1ed9c. Khi m\u1ed9t nh\u00e0 ph\u00e1t tri\u1ec3n nh\u00ecn v\u00e0o s\u01a1 \u0111\u1ed3 Crow\u2019s Foot, h\u1ecd bi\u1ebft ch\u00ednh x\u00e1c kh\u00f3a ngo\u1ea1i n\u00e0o c\u1ea7n vi\u1ebft.<\/p>\n Tr\u1ecdng t\u00e2m:<\/strong> T\u00ednh to\u00e0n v\u1eb9n d\u1eef li\u1ec7u v\u00e0 t\u1ed1c \u0111\u1ed9 truy v\u1ea5n.<\/p>\n<\/li>\n Khuy\u1ebfn ngh\u1ecb:<\/strong>S\u1eed d\u1ee5ng Crow\u2019s Foot cho l\u1edbp s\u01a1 \u0111\u1ed3 v\u1eadt l\u00fd.<\/p>\n<\/li>\n<\/ul>\n Trong ki\u1ebfn tr\u00fac microservices, c\u00e1c \u0111\u1ed9i th\u01b0\u1eddng ho\u1ea1t \u0111\u1ed9ng trong c\u00e1c ng\u1eef c\u1ea3nh \u0111\u01b0\u1ee3c gi\u1edbi h\u1ea1n. S\u01a1 \u0111\u1ed3 l\u1edbp UML c\u00f3 gi\u00e1 tr\u1ecb \u1edf \u0111\u00e2y \u0111\u1ec3 x\u00e1c \u0111\u1ecbnh ranh gi\u1edbi gi\u1eefa c\u00e1c d\u1ecbch v\u1ee5. Ch\u00fang gi\u00fap h\u00ecnh dung c\u00e1ch m\u1ed9t th\u1ef1c th\u1ec3 trong m\u1ed9t d\u1ecbch v\u1ee5 li\u00ean quan \u0111\u1ebfn th\u1ef1c th\u1ec3 trong d\u1ecbch v\u1ee5 kh\u00e1c, th\u01b0\u1eddng th\u00f4ng qua h\u1ee3p \u0111\u1ed3ng API thay v\u00ec c\u00e1c li\u00ean k\u1ebft c\u01a1 s\u1edf d\u1eef li\u1ec7u tr\u1ef1c ti\u1ebfp.<\/p>\n Tr\u1ecdng t\u00e2m:<\/strong> Ranh gi\u1edbi d\u1ecbch v\u1ee5 v\u00e0 \u00e1nh x\u1ea1 \u0111\u1ed1i t\u01b0\u1ee3ng.<\/p>\n<\/li>\n Khuy\u1ebfn ngh\u1ecb:<\/strong> S\u1eed d\u1ee5ng UML cho m\u00f4 h\u00ecnh mi\u1ec1n, sau \u0111\u00f3 chuy\u1ec3n \u0111\u1ed5i sang bi\u1ec3u t\u01b0\u1ee3ng Crow\u2019s Foot cho c\u01a1 s\u1edf d\u1eef li\u1ec7u d\u1ecbch v\u1ee5 c\u1ee5 th\u1ec3.<\/p>\n<\/li>\n<\/ul>\n Khi ki\u1ec3m to\u00e1n m\u1ed9t h\u1ec7 th\u1ed1ng hi\u1ec7n c\u00f3 ho\u1eb7c chuy\u1ec3n \u0111\u1ed5i t\u1eeb n\u1ec1n t\u1ea3ng c\u0169, k\u00fd hi\u1ec7u Chen c\u00f3 th\u1ec3 xu\u1ea5t hi\u1ec7n trong t\u00e0i li\u1ec7u. Hi\u1ec3u r\u00f5 n\u00f3 l\u00e0 \u0111i\u1ec1u c\u1ea7n thi\u1ebft \u0111\u1ec3 chuy\u1ec3n \u0111\u1ed5i ch\u00ednh x\u00e1c. B\u1ea1n ph\u1ea3i c\u00f3 kh\u1ea3 n\u0103ng chuy\u1ec3n \u0111\u1ed5i c\u00e1c h\u00ecnh thoi v\u00e0 h\u00ecnh elip tr\u1edf l\u1ea1i c\u1ea5u tr\u00fac b\u1ea3ng hi\u1ec7n \u0111\u1ea1i.<\/p>\n Tr\u1ecdng t\u00e2m:<\/strong>B\u1ea3o t\u1ed3n logic kinh doanh.<\/p>\n<\/li>\n Khuy\u1ebfn ngh\u1ecb:<\/strong>Chuy\u1ec3n \u0111\u1ed5i k\u00fd hi\u1ec7u Chen sang Crow\u2019s Foot \u0111\u1ec3 tri\u1ec3n khai, \u0111\u1ed3ng th\u1eddi gi\u1eef l\u1ea1i k\u00fd hi\u1ec7u Chen g\u1ed1c \u0111\u1ec3 tham kh\u1ea3o.<\/p>\n<\/li>\n<\/ul>\n D\u00f9 ch\u1ecdn k\u00fd hi\u1ec7u n\u00e0o, m\u1ed9t s\u1ed1 nguy\u00ean t\u1eafc nh\u1ea5t \u0111\u1ecbnh \u0111\u1ec1u \u00e1p d\u1ee5ng ph\u1ed5 bi\u1ebfn \u0111\u1ec3 \u0111\u1ea3m b\u1ea3o h\u1ec7 th\u1ed1ng c\u00f3 th\u1ec3 duy tr\u00ec v\u00e0 m\u1edf r\u1ed9ng \u0111\u01b0\u1ee3c.<\/p>\n T\u00ednh nh\u1ea5t qu\u00e1n l\u00e0 ch\u00eca kh\u00f3a:<\/strong>Kh\u00f4ng \u0111\u01b0\u1ee3c tr\u1ed9n c\u00e1c k\u00fd hi\u1ec7u trong c\u00f9ng m\u1ed9t t\u00e0i li\u1ec7u. N\u1ebfu b\u1ea1n b\u1eaft \u0111\u1ea7u b\u1eb1ng Crow\u2019s Foot th\u00ec h\u00e3y k\u1ebft th\u00fac b\u1eb1ng Crow\u2019s Foot. Vi\u1ec7c chuy\u1ec3n \u0111\u1ed5i gi\u1eefa c\u00e1c k\u00fd hi\u1ec7u gi\u1eefa ch\u1eebng s\u1ebd g\u00e2y nh\u1ea7m l\u1eabn v\u1ec1 \u00fd ngh\u0129a c\u1ee7a t\u1eebng k\u00fd hi\u1ec7u c\u1ee5 th\u1ec3.<\/p>\n<\/li>\n Quy \u01b0\u1edbc \u0111\u1eb7t t\u00ean:<\/strong>\u0110\u1ea3m b\u1ea3o t\u00ean th\u1ef1c th\u1ec3 v\u00e0 thu\u1ed9c t\u00ednh tu\u00e2n theo quy \u01b0\u1edbc snake_case ho\u1eb7c camelCase nh\u1ea5t qu\u00e1n tr\u00ean to\u00e0n b\u1ed9 s\u01a1 \u0111\u1ed3. Nh\u1eefng t\u00ean m\u01a1 h\u1ed3 nh\u01b0 \u201cData\u201d hay \u201cInfo\u201d l\u00e0 d\u1ea5u hi\u1ec7u c\u1ea3nh b\u00e1o.<\/p>\n<\/li>\n Chu\u1ea9n h\u00f3a:<\/strong>\u00c1p d\u1ee5ng c\u00e1c quy t\u1eafc chu\u1ea9n h\u00f3a (t\u1ed1i \u0111a \u0111\u1ebfn 3NF ho\u1eb7c BCNF) tr\u01b0\u1edbc khi ho\u00e0n thi\u1ec7n s\u01a1 \u0111\u1ed3. M\u1ed9t s\u01a1 \u0111\u1ed3 ch\u01b0a \u0111\u01b0\u1ee3c chu\u1ea9n h\u00f3a s\u1ebd d\u1eabn \u0111\u1ebfn d\u01b0 th\u1eeba d\u1eef li\u1ec7u v\u00e0 c\u00e1c l\u1ed7i c\u1eadp nh\u1eadt.<\/p>\n<\/li>\n T\u00e0i li\u1ec7u r\u00e0ng bu\u1ed9c:<\/strong>Ghi r\u00f5 r\u00e0ng c\u00e1c r\u00e0ng bu\u1ed9c duy nh\u1ea5t v\u00e0 r\u00e0ng bu\u1ed9c ki\u1ec3m tra. C\u00e1c k\u00fd hi\u1ec7u tr\u1ef1c quan th\u1ec3 hi\u1ec7n m\u1ed1i quan h\u1ec7, nh\u01b0ng c\u00e1c ghi ch\u00fa v\u0103n b\u1ea3n th\u01b0\u1eddng l\u00e0m r\u00f5 c\u00e1c quy t\u1eafc kinh doanh.<\/p>\n<\/li>\n Ki\u1ec3m so\u00e1t phi\u00ean b\u1ea3n:<\/strong>Xem s\u01a1 \u0111\u1ed3 ER nh\u01b0 m\u00e3 ngu\u1ed3n. L\u01b0u tr\u1eef ch\u00fang trong h\u1ec7 th\u1ed1ng ki\u1ec3m so\u00e1t phi\u00ean b\u1ea3n c\u1ee7a b\u1ea1n. Nh\u1eefng thay \u0111\u1ed5i v\u00e0o c\u1ea5u tr\u00fac d\u1eef li\u1ec7u c\u1ea7n \u0111\u01b0\u1ee3c xem x\u00e9t k\u1ef9 nh\u01b0 c\u00e1c thay \u0111\u1ed5i m\u00e3 ngu\u1ed3n.<\/p>\n<\/li>\n<\/ul>\n Ngay c\u1ea3 nh\u1eefng ki\u1ebfn tr\u00fac s\u01b0 c\u00f3 kinh nghi\u1ec7m c\u0169ng m\u1eafc sai l\u1ea7m khi tr\u1ef1c quan h\u00f3a c\u1ea5u tr\u00fac d\u1eef li\u1ec7u. Nh\u1eadn th\u1ee9c \u0111\u01b0\u1ee3c nh\u1eefng l\u1ed7i ph\u1ed5 bi\u1ebfn n\u00e0y c\u00f3 th\u1ec3 ti\u1ebft ki\u1ec7m r\u1ea5t nhi\u1ec1u th\u1eddi gian trong qu\u00e1 tr\u00ecnh ph\u00e1t tri\u1ec3n.<\/p>\n M\u1ed9t \u0111\u01b0\u1eddng m\u1ed1i quan h\u1ec7 kh\u00f4ng c\u00f3 v\u00f2ng tr\u00f2n hay thanh ngang ng\u1ee5 \u00fd m\u1ed9t gi\u00e1 tr\u1ecb m\u1eb7c \u0111\u1ecbnh, t\u00f9y thu\u1ed9c v\u00e0o c\u00f4ng c\u1ee5. Lu\u00f4n ph\u1ea3i n\u00eau r\u00f5 r\u00e0ng n\u1ebfu kh\u00f3a ngo\u1ea1i c\u00f3 th\u1ec3 l\u00e0 null. Trong Crow\u2019s Foot, \u0111i\u1ec1u n\u00e0y l\u00e0 m\u1ed9t v\u00f2ng tr\u00f2n. Trong UML, \u0111\u00f3 l\u00e0 b\u1ed9i s\u1ed1 0..1. Vi\u1ec7c suy \u0111o\u00e1n l\u00e0 m\u1ed9t th\u00f3i quen nguy hi\u1ec3m.<\/p>\n M\u1eb7c d\u00f9 k\u00fd hi\u1ec7u Chen x\u1eed l\u00fd t\u1ed1t c\u00e1c m\u1ed1i quan h\u1ec7 tam ph\u00e2n, nh\u01b0ng c\u00e1c c\u01a1 s\u1edf d\u1eef li\u1ec7u quan h\u1ec7 kh\u00f4ng h\u1ed7 tr\u1ee3 ch\u00fang m\u1ed9t c\u00e1ch t\u1ef1 nhi\u00ean. M\u1ed9t m\u1ed1i quan h\u1ec7 gi\u1eefa ba b\u1ea3ng th\u01b0\u1eddng c\u1ea7n \u0111\u01b0\u1ee3c chia nh\u1ecf th\u00e0nh c\u00e1c m\u1ed1i quan h\u1ec7 nh\u1ecb ph\u00e2n ho\u1eb7c m\u1ed9t th\u1ef1c th\u1ec3 li\u00ean k\u1ebft. Vi\u1ec7c m\u00f4 h\u00ecnh h\u00f3a m\u1ed9t li\u00ean k\u1ebft ba chi\u1ec1u tr\u1ef1c ti\u1ebfp c\u00f3 th\u1ec3 d\u1eabn \u0111\u1ebfn kh\u00f3 kh\u0103n trong tri\u1ec3n khai.<\/p>\n Trong UML, s\u1ef1 kh\u00e1c bi\u1ec7t gi\u1eefa h\u00ecnh thoi r\u1ed7ng v\u00e0 h\u00ecnh thoi \u0111\u1ea7y l\u00e0 r\u1ea5t quan tr\u1ecdng. H\u00ecnh thoi r\u1ed7ng c\u00f3 ngh\u0129a l\u00e0 con c\u00f3 th\u1ec3 t\u1ed3n t\u1ea1i m\u00e0 kh\u00f4ng c\u1ea7n cha. H\u00ecnh thoi \u0111\u1ea7y c\u00f3 ngh\u0129a l\u00e0 kh\u00f4ng th\u1ec3. Vi\u1ec7c nh\u1ea7m l\u1eabn gi\u1eefa ch\u00fang c\u00f3 th\u1ec3 d\u1eabn \u0111\u1ebfn v\u1ea5n \u0111\u1ec1 d\u1eef li\u1ec7u b\u1ecb b\u1ecf r\u01a1i, khi c\u00e1c b\u1ea3n ghi con b\u1ecb x\u00f3a ho\u1eb7c l\u01b0u tr\u1eef sai c\u00e1ch.<\/p>\n M\u1ed9t tham chi\u1ebfu v\u00f2ng x\u1ea3y ra khi B\u1ea3ng A tham chi\u1ebfu B\u1ea3ng B, v\u00e0 B\u1ea3ng B tham chi\u1ebfu B\u1ea3ng A. M\u1eb7c d\u00f9 \u0111\u00f4i khi h\u1ee3p l\u1ec7 (v\u00ed d\u1ee5: m\u1ed9t c\u1ea5u tr\u00fac ph\u00e2n c\u1ea5p), \u0111i\u1ec1u n\u00e0y l\u00e0m ph\u1ee9c t\u1ea1p qu\u00e1 tr\u00ecnh sao l\u01b0u v\u00e0 kh\u00f4i ph\u1ee5c. \u0110\u1ea3m b\u1ea3o s\u01a1 \u0111\u1ed3 r\u00f5 r\u00e0ng ch\u1ec9 ra h\u01b0\u1edbng c\u1ee7a m\u1ed1i ph\u1ee5 thu\u1ed9c \u0111\u1ec3 tr\u00e1nh l\u1ed7i th\u1ee9 t\u1ef1 t\u1ea1o.<\/p>\n C\u00e1c h\u1ec7 th\u1ed1ng hi\u1ec7n \u0111\u1ea1i th\u01b0\u1eddng y\u00eau c\u1ea7u x\u00f3a m\u1ec1m (\u0111\u00e1nh d\u1ea5u m\u1ed9t h\u00e0ng l\u00e0 kh\u00f4ng ho\u1ea1t \u0111\u1ed9ng thay v\u00ec x\u00f3a n\u00f3 \u0111i). M\u1ed9t s\u01a1 \u0111\u1ed3 n\u00ean ch\u1ec9 ra n\u01a1i \u0111\u1eb7t c\u1ed9t `deleted_at` ho\u1eb7c `is_active`. \u0110\u00e2y l\u00e0 m\u1ed9t thay \u0111\u1ed5i logic \u1ea3nh h\u01b0\u1edfng \u0111\u1ebfn l\u01b0\u1ee3c \u0111\u1ed3 v\u1eadt l\u00fd.<\/p>\n Th\u01b0\u1eddng xuy\u00ean x\u1ea3y ra khi m\u1ed9t d\u1ef1 \u00e1n b\u1eaft \u0111\u1ea7u b\u1eb1ng Chen \u0111\u1ec3 l\u1eadp k\u1ebf ho\u1ea1ch c\u1ea5p cao v\u00e0 k\u1ebft th\u00fac b\u1eb1ng Crow\u2019s Foot \u0111\u1ec3 tri\u1ec3n khai. Hi\u1ec3u r\u00f5 s\u1ef1 \u00e1nh x\u1ea1 gi\u1eefa ch\u00fang \u0111\u1ea3m b\u1ea3o t\u00ednh to\u00e0n v\u1eb9n d\u1eef li\u1ec7u \u0111\u01b0\u1ee3c duy tr\u00ec trong qu\u00e1 tr\u00ecnh chuy\u1ec3n \u0111\u1ed5i.<\/p>\n Chen sang Crow\u2019s Foot:<\/strong>Chuy\u1ec3n h\u00ecnh thoi th\u00e0nh \u0111\u01b0\u1eddng th\u1eb3ng. Chuy\u1ec3n c\u00e1c nh\u00e3n (1, N) th\u00e0nh k\u00fd hi\u1ec7u ch\u00e2n chim. Th\u00eam c\u00e1c thanh\/\u0111\u01b0\u1eddng tr\u00f2n m\u00f4 t\u1ea3 d\u1ef1a tr\u00ean c\u00e1c quy t\u1eafc kinh doanh ng\u1ea7m \u0111\u1ecbnh t\u1eeb thi\u1ebft k\u1ebf ban \u0111\u1ea7u.<\/p>\n<\/li>\n UML sang Crow\u2019s Foot:<\/strong>Lo\u1ea1i b\u1ecf c\u00e1c thao t\u00e1c l\u1edbp (ph\u01b0\u01a1ng th\u1ee9c). \u0110\u01a1n gi\u1ea3n h\u00f3a c\u00e1c \u0111\u01b0\u1eddng bi\u1ec3u di\u1ec5n t\u00edch h\u1ee3p\/th\u00e0nh ph\u1ea7n th\u00e0nh kh\u00f3a ngo\u1ea1i ti\u00eau chu\u1ea9n. \u0110i\u1ec1u ch\u1ec9nh k\u00fd hi\u1ec7u b\u1ed9i s\u1ed1 \u0111\u1ec3 ph\u00f9 h\u1ee3p v\u1edbi k\u00fd hi\u1ec7u Crow\u2019s Foot.<\/p>\n<\/li>\n Crow\u2019s Foot sang UML:<\/strong>Th\u00eam c\u1ea5u tr\u00fac h\u1ed9p l\u1edbp. \u00c1nh x\u1ea1 c\u00e1c \u0111\u01b0\u1eddng quan h\u1ec7 th\u00e0nh m\u0169i t\u00ean li\u00ean k\u1ebft. X\u00e1c \u0111\u1ecbnh m\u1ed1i quan h\u1ec7 l\u00e0 t\u00edch h\u1ee3p hay th\u00e0nh ph\u1ea7n d\u1ef1a tr\u00ean v\u00f2ng \u0111\u1eddi d\u1eef li\u1ec7u.<\/p>\n<\/li>\n<\/ul>\n Vi\u1ec7c l\u1ef1a ch\u1ecdn k\u00fd hi\u1ec7u kh\u00f4ng ch\u1ec9 mang t\u00ednh th\u1ea9m m\u1ef9; n\u00f3 l\u00e0 m\u1ed9t c\u00f4ng c\u1ee5 giao ti\u1ebfp quy\u1ebft \u0111\u1ecbnh c\u00e1ch hi\u1ec3u v\u00e0 x\u00e2y d\u1ef1ng c\u01a1 s\u1edf d\u1eef li\u1ec7u. Chen cung c\u1ea5p s\u1ef1 r\u00f5 r\u00e0ng v\u1ec1 kh\u00e1i ni\u1ec7m, Crow\u2019s Foot mang l\u1ea1i \u0111\u1ed9 ch\u00ednh x\u00e1c quan h\u1ec7, c\u00f2n UML mang \u0111\u1ebfn s\u1ef1 t\u00edch h\u1ee3p h\u01b0\u1edbng \u0111\u1ed1i t\u01b0\u1ee3ng.<\/p>\n B\u1eb1ng c\u00e1ch ch\u1ecdn k\u00fd hi\u1ec7u ph\u00f9 h\u1ee3p v\u1edbi chuy\u00ean m\u00f4n c\u1ee7a \u0111\u1ed9i ng\u0169 v\u00e0 ki\u1ebfn tr\u00fac h\u1ec7 th\u1ed1ng c\u1ee7a b\u1ea1n, b\u1ea1n s\u1ebd gi\u1ea3m thi\u1ec3u r\u1ee7i ro hi\u1ec3u l\u1ea7m. M\u1ed9t l\u01b0\u1ee3c \u0111\u1ed3 \u0111\u01b0\u1ee3c t\u00e0i li\u1ec7u h\u00f3a t\u1ed1t \u0111\u00f3ng vai tr\u00f2 nh\u01b0 m\u1ed9t h\u1ee3p \u0111\u1ed3ng gi\u1eefa d\u1eef li\u1ec7u v\u00e0 \u1ee9ng d\u1ee5ng. D\u00f9 b\u1ea1n \u0111ang v\u1ebd h\u00ecnh thoi, ch\u00e2n chim hay h\u1ed9p l\u1edbp, m\u1ee5c ti\u00eau v\u1eabn nh\u01b0 nhau: t\u1ea1o n\u00ean n\u1ec1n t\u1ea3ng \u1ed5n \u0111\u1ecbnh cho d\u1eef li\u1ec7u c\u1ee7a b\u1ea1n.<\/p>\n D\u00e0nh th\u1eddi gian cho giai \u0111o\u1ea1n m\u00f4 h\u00ecnh h\u00f3a. Chi ph\u00ed thay \u0111\u1ed5i m\u1ed9t s\u01a1 \u0111\u1ed3 l\u00e0 r\u1ea5t nh\u1ecf so v\u1edbi chi ph\u00ed t\u00e1i c\u1ea5u tr\u00fac c\u01a1 s\u1edf d\u1eef li\u1ec7u \u0111\u00e3 tri\u1ec3n khai. Ch\u1ecdn ng\u00f4n ng\u1eef tr\u1ef1c quan m\u1ed9t c\u00e1ch kh\u00f4n kh\u00e9o, v\u00e0 \u0111\u1ea3m b\u1ea3o m\u1ecdi b\u00ean li\u00ean quan \u0111\u1ec1u n\u00f3i c\u00f9ng m\u1ed9t th\u1ee9 ti\u1ebfng.<\/p>\n","protected":false},"excerpt":{"rendered":" Thi\u1ebft k\u1ebf m\u1ed9t l\u01b0\u1ee3c \u0111\u1ed3 c\u01a1 s\u1edf d\u1eef li\u1ec7u m\u1ea1nh m\u1ebd \u0111\u00f2i h\u1ecfi h\u01a1n c\u1ea3 vi\u1ec7c bi\u1ebft b\u1ea3ng n\u00e0o ch\u1ee9a d\u1eef li\u1ec7u g\u00ec. N\u00f3 \u0111\u00f2i h\u1ecfi m\u1ed9t ng\u00f4n ng\u1eef r\u00f5…<\/p>\n","protected":false},"author":1,"featured_media":76,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_yoast_wpseo_title":"C\u00e1c k\u00fd hi\u1ec7u s\u01a1 \u0111\u1ed3 ER: So s\u00e1nh Crow\u2019s Foot, UML, Chen","_yoast_wpseo_metadesc":"So s\u00e1nh c\u00e1c k\u00fd hi\u1ec7u s\u01a1 \u0111\u1ed3 ER nh\u01b0 Crow\u2019s Foot, UML v\u00e0 Chen. H\u1ecdc c\u00e1ch s\u1eed d\u1ee5ng t\u1eebng lo\u1ea1i ph\u00f9 h\u1ee3p v\u1edbi thi\u1ebft k\u1ebf c\u01a1 s\u1edf d\u1eef li\u1ec7u, m\u00f4 h\u00ecnh h\u00f3a l\u01b0\u1ee3c \u0111\u1ed3 v\u00e0 kh\u1ea3 n\u0103ng t\u01b0\u01a1ng th\u00edch v\u1edbi stack.","inline_featured_image":false,"fifu_image_url":"","fifu_image_alt":"","footnotes":""},"categories":[6],"tags":[10,11],"class_list":["post-75","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-erd","tag-academic","tag-erd"],"yoast_head":"\n\u01afu \u0111i\u1ec3m v\u00e0 tr\u01b0\u1eddng h\u1ee3p s\u1eed d\u1ee5ng<\/h3>\n
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\ud83e\uddb5 K\u00fd hi\u1ec7u ch\u00e2n chim: Chu\u1ea9n chu\u1ea9n quan h\u1ec7<\/h2>\n
C\u00fa ph\u00e1p c\u1ed1t l\u00f5i v\u00e0 c\u00e1c y\u1ebfu t\u1ed1 h\u00ecnh \u1ea3nh<\/h3>\n
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\u01afu \u0111i\u1ec3m v\u00e0 c\u00e1c tr\u01b0\u1eddng h\u1ee3p s\u1eed d\u1ee5ng<\/h3>\n
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\ud83d\udcd0 S\u01a1 \u0111\u1ed3 l\u1edbp UML: C\u1ea7u n\u1ed1i h\u01b0\u1edbng \u0111\u1ed1i t\u01b0\u1ee3ng<\/h2>\n
Ng\u1eef ph\u00e1p c\u1ed1t l\u00f5i v\u00e0 c\u00e1c y\u1ebfu t\u1ed1 tr\u1ef1c quan<\/h3>\n
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\u0110i\u1ec3m m\u1ea1nh v\u00e0 tr\u01b0\u1eddng h\u1ee3p s\u1eed d\u1ee5ng<\/h3>\n
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\ud83d\udcca So s\u00e1nh song song<\/h2>\n
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\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \ud83d\udd0d Ch\u1ecdn k\u00fd hi\u1ec7u ph\u00f9 h\u1ee3p cho h\u1ec7 th\u1ed1ng c\u1ee7a b\u1ea1n<\/h2>\n
T\u00ecnh hu\u1ed1ng 1: Kho d\u1eef li\u1ec7u quan h\u1ec7 thu\u1ea7n t\u00fay<\/h3>\n
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T\u00ecnh hu\u1ed1ng 2: Microservices v\u00e0 Thi\u1ebft k\u1ebf h\u01b0\u1edbng mi\u1ec1n<\/h3>\n
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T\u00ecnh hu\u1ed1ng 3: Chuy\u1ec3n \u0111\u1ed5i t\u1eeb h\u1ec7 th\u1ed1ng c\u0169 v\u00e0 ki\u1ec3m to\u00e1n<\/h3>\n
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\ud83d\udee0\ufe0f C\u00e1c th\u1ef1c h\u00e0nh t\u1ed1t nh\u1ea5t cho m\u00f4 h\u00ecnh h\u00f3a d\u1eef li\u1ec7u<\/h2>\n
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\ud83d\udeab Nh\u1eefng sai l\u1ea7m ph\u1ed5 bi\u1ebfn c\u1ea7n tr\u00e1nh<\/h2>\n
1. B\u1ecf qua kh\u1ea3 n\u0103ng null<\/h3>\n
2. M\u00f4 h\u00ecnh h\u00f3a qu\u00e1 m\u1ee9c c\u00e1c m\u1ed1i quan h\u1ec7 tam ph\u00e2n<\/h3>\n
3. Nh\u1ea7m l\u1eabn gi\u1eefa t\u00edch h\u1ee3p v\u00e0 k\u1ebft h\u1ee3p<\/h3>\n
4. Ph\u1ee5 thu\u1ed9c v\u00f2ng l\u1eb7p<\/h3>\n
5. B\u1ecf qua x\u00f3a m\u1ec1m<\/h3>\n
\ud83d\udd04 Chuy\u1ec3n \u0111\u1ed5i gi\u1eefa c\u00e1c k\u00fd hi\u1ec7u<\/h2>\n
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\ud83d\udcdd Nh\u1eefng suy ngh\u0129 cu\u1ed1i c\u00f9ng v\u1ec1 m\u00f4 h\u00ecnh h\u00f3a d\u1eef li\u1ec7u<\/h2>\n