{"id":1627,"date":"2026-04-09T02:30:54","date_gmt":"2026-04-09T02:30:54","guid":{"rendered":"https:\/\/www.viz-note.com\/vi\/erd-troubleshooting-slow-query-schema-design\/"},"modified":"2026-04-09T02:30:54","modified_gmt":"2026-04-09T02:30:54","slug":"erd-troubleshooting-slow-query-schema-design","status":"publish","type":"post","link":"https:\/\/www.viz-note.com\/vi\/erd-troubleshooting-slow-query-schema-design\/","title":{"rendered":"Kh\u1eafc ph\u1ee5c s\u1ef1 c\u1ed1 s\u01a1 \u0111\u1ed3 quan h\u1ec7 th\u1ef1c th\u1ec3: Ch\u1ea9n \u0111o\u00e1n c\u00e1c truy v\u1ea5n ch\u1eadm do thi\u1ebft k\u1ebf l\u01b0\u1ee3c \u0111\u1ed3 k\u00e9m hi\u1ec7u qu\u1ea3"},"content":{"rendered":"<p>Hi\u1ec7u su\u1ea5t c\u01a1 s\u1edf d\u1eef li\u1ec7u th\u01b0\u1eddng v\u00f4 h\u00ecnh cho \u0111\u1ebfn khi tr\u1edf th\u00e0nh \u0111i\u1ec3m ngh\u1ebdn nghi\u00eam tr\u1ecdng. Khi ng\u01b0\u1eddi d\u00f9ng g\u1eb7p \u0111\u1ed9 tr\u1ec5, th\u1eddi gian ch\u1edd v\u01b0\u1ee3t qu\u00e1 gi\u1edbi h\u1ea1n ho\u1eb7c giao di\u1ec7n kh\u00f4ng ph\u1ea3n h\u1ed3i, nguy\u00ean nh\u00e2n g\u1ed1c r\u1ec5 th\u01b0\u1eddng n\u1eb1m s\u00e2u b\u00ean d\u01b0\u1edbi l\u1edbp \u1ee9ng d\u1ee5ng. N\u00f3 n\u1eb1m \u1edf ki\u1ebfn tr\u00fac d\u1eef li\u1ec7u ch\u00ednh n\u00f3. B\u1ea3n v\u1ebd thi\u1ebft k\u1ebf \u0111i\u1ec1u khi\u1ec3n c\u00e1ch d\u1eef li\u1ec7u \u0111\u01b0\u1ee3c c\u1ea5u tr\u00fac, li\u00ean k\u1ebft v\u00e0 l\u01b0u tr\u1eef ch\u00ednh l\u00e0 s\u01a1 \u0111\u1ed3 quan h\u1ec7 th\u1ef1c th\u1ec3 (ERD). M\u1ed9t s\u01a1 \u0111\u1ed3 ERD \u0111\u01b0\u1ee3c x\u00e2y d\u1ef1ng t\u1ed1t \u0111\u1ea3m b\u1ea3o t\u00ednh to\u00e0n v\u1eb9n d\u1eef li\u1ec7u v\u00e0 truy xu\u1ea5t hi\u1ec7u qu\u1ea3. Ng\u01b0\u1ee3c l\u1ea1i, m\u1ed9t s\u01a1 \u0111\u1ed3 l\u1ed7i th\u1eddi s\u1ebd g\u00e2y ra \u0111\u1ed9 tr\u1ec5 m\u00e0 b\u1ea5t k\u1ef3 m\u1ee9c \u0111\u1ed9 l\u01b0u tr\u1eef t\u1ea1m \u1ee9ng d\u1ee5ng n\u00e0o c\u0169ng kh\u00f4ng th\u1ec3 kh\u1eafc ph\u1ee5c ho\u00e0n to\u00e0n.<\/p>\n<p>H\u01b0\u1edbng d\u1eabn n\u00e0y cung c\u1ea5p c\u00e1i nh\u00ecn s\u00e2u s\u1eafc v\u1ec1 vi\u1ec7c kh\u1eafc ph\u1ee5c c\u00e1c truy v\u1ea5n ch\u1eadm b\u1eb1ng c\u00e1ch ph\u00e2n t\u00edch thi\u1ebft k\u1ebf l\u01b0\u1ee3c \u0111\u1ed3 n\u1ec1n t\u1ea3ng. Ch\u00fang ta s\u1ebd kh\u00e1m ph\u00e1 c\u00e1ch c\u00e1c quy\u1ebft \u0111\u1ecbnh c\u1ea5u tr\u00fac trong ERD \u1ea3nh h\u01b0\u1edfng tr\u1ef1c ti\u1ebfp \u0111\u1ebfn k\u1ebf ho\u1ea1ch th\u1ef1c thi truy v\u1ea5n, c\u00e1c thao t\u00e1c I\/O v\u00e0 kh\u1ea3 n\u0103ng ph\u1ea3n h\u1ed3i t\u1ed5ng th\u1ec3 c\u1ee7a h\u1ec7 th\u1ed1ng. B\u1eb1ng c\u00e1ch hi\u1ec3u r\u00f5 c\u01a1 ch\u1ebf thi\u1ebft k\u1ebf quan h\u1ec7, b\u1ea1n c\u00f3 th\u1ec3 ch\u1ea9n \u0111o\u00e1n c\u00e1c v\u1ea5n \u0111\u1ec1 hi\u1ec7u su\u1ea5t \u1edf g\u1ed1c r\u1ec5 thay v\u00ec ch\u1ec9 \u0111i\u1ec1u tr\u1ecb tri\u1ec7u ch\u1ee9ng.<\/p>\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter\"><img alt=\"Charcoal sketch infographic illustrating Entity Relationship Diagram troubleshooting for slow database queries, showing structural anti-patterns like missing foreign keys and excessive normalization, cardinality impacts on join performance, data type optimization strategies, indexing best practices, and a schema validation checklist for diagnosing poor database design\" decoding=\"async\" src=\"https:\/\/www.viz-note.com\/wp-content\/uploads\/2026\/04\/erd-troubleshooting-infographic-charcoal-sketch.jpg\"\/><\/figure>\n<\/div>\n<h2>\ud83c\udfd7\ufe0f N\u1ec1n t\u1ea3ng: ERD \u1ea3nh h\u01b0\u1edfng \u0111\u1ebfn vi\u1ec7c th\u1ef1c thi truy v\u1ea5n nh\u01b0 th\u1ebf n\u00e0o<\/h2>\n<p>Tr\u01b0\u1edbc khi ch\u1ea9n \u0111o\u00e1n m\u1ed9t v\u1ea5n \u0111\u1ec1, \u0111i\u1ec1u thi\u1ebft y\u1ebfu l\u00e0 ph\u1ea3i hi\u1ec3u m\u1ed1i quan h\u1ec7 gi\u1eefa bi\u1ec3u di\u1ec5n tr\u1ef1c quan d\u1eef li\u1ec7u v\u00e0 vi\u1ec7c th\u1ef1c thi l\u1ec7nh v\u1eadt l\u00fd. M\u1ed9t ERD kh\u00f4ng ch\u1ec9 \u0111\u01a1n thu\u1ea7n l\u00e0 s\u01a1 \u0111\u1ed3 t\u00e0i li\u1ec7u; n\u00f3 l\u00e0 m\u1ed9t t\u1eadp h\u1ee3p c\u00e1c quy t\u1eafc m\u00e0 b\u1ed9 \u0111\u1ed9ng c\u01a1 c\u01a1 s\u1edf d\u1eef li\u1ec7u ph\u1ea3i tu\u00e2n th\u1ee7. M\u1ed7i \u0111\u01b0\u1eddng n\u1ed1i gi\u1eefa c\u00e1c b\u1ea3ng, m\u1ed7i r\u00e0ng bu\u1ed9c \u0111\u01b0\u1ee3c x\u00e1c \u0111\u1ecbnh v\u00e0 m\u1ed7i ki\u1ec3u d\u1eef li\u1ec7u \u0111\u01b0\u1ee3c ch\u1ec9 \u0111\u1ecbnh \u0111\u1ec1u quy \u0111\u1ecbnh c\u00e1ch b\u1ed9 \u0111\u1ed9ng c\u01a1 l\u01b0u tr\u1eef \u0111\u1ecdc v\u00e0 ghi th\u00f4ng tin.<\/p>\n<p>Khi m\u1ed9t truy v\u1ea5n \u0111\u01b0\u1ee3c g\u1eedi \u0111i, b\u1ed9 t\u1ed1i \u01b0u h\u00f3a c\u01a1 s\u1edf d\u1eef li\u1ec7u s\u1ebd ph\u00e2n t\u00edch y\u00eau c\u1ea7u d\u1ef1a tr\u00ean th\u00f4ng tin m\u00f4 t\u1ea3 l\u01b0\u1ee3c \u0111\u1ed3. N\u1ebfu l\u01b0\u1ee3c \u0111\u1ed3 m\u01a1 h\u1ed3 ho\u1eb7c k\u00e9m hi\u1ec7u qu\u1ea3, b\u1ed9 t\u1ed1i \u01b0u h\u00f3a c\u00f3 th\u1ec3 ch\u1ecdn m\u1ed9t con \u0111\u01b0\u1eddng kh\u00f4ng t\u1ed1i \u01b0u. \u0110i\u1ec1u n\u00e0y th\u01b0\u1eddng th\u1ec3 hi\u1ec7n d\u01b0\u1edbi d\u1ea1ng qu\u00e9t to\u00e0n b\u1ed9 b\u1ea3ng thay v\u00ec t\u00ecm ki\u1ebfm ch\u1ec9 m\u1ee5c, ho\u1eb7c m\u1ed9t ph\u00e9p n\u1ed1i v\u00f2ng l\u1eb7p l\u1ed3ng nhau l\u00e0m t\u0103ng th\u1eddi gian x\u1eed l\u00fd theo c\u1ea5p s\u1ed1 nh\u00e2n.<\/p>\n<p>C\u00e1c khu v\u1ef1c ch\u00ednh m\u00e0 ERD \u1ea3nh h\u01b0\u1edfng \u0111\u1ebfn hi\u1ec7u su\u1ea5t bao g\u1ed3m:<\/p>\n<ul>\n<li><strong>\u0110\u1ed9 ph\u1ee9c t\u1ea1p c\u1ee7a ph\u00e9p n\u1ed1i:<\/strong> S\u1ed1 l\u01b0\u1ee3ng m\u1ed1i quan h\u1ec7 \u0111\u01b0\u1ee3c x\u00e1c \u0111\u1ecbnh quy\u1ebft \u0111\u1ecbnh s\u1ed1 l\u01b0\u1ee3ng ph\u00e9p n\u1ed1i c\u1ea7n thi\u1ebft \u0111\u1ec3 truy xu\u1ea5t d\u1eef li\u1ec7u li\u00ean quan.<\/li>\n<li><strong>C\u00e1c r\u00e0ng bu\u1ed9c to\u00e0n v\u1eb9n d\u1eef li\u1ec7u:<\/strong> Kh\u00f3a ngo\u1ea1i v\u00e0 c\u00e1c r\u00e0ng bu\u1ed9c duy nh\u1ea5t l\u00e0m t\u0103ng chi ph\u00ed cho thao t\u00e1c ghi nh\u01b0ng c\u00f3 th\u1ec3 t\u1ed1i \u01b0u h\u00f3a thao t\u00e1c \u0111\u1ecdc.<\/li>\n<li><strong>M\u1ee9c \u0111\u1ed9 chu\u1ea9n h\u00f3a:<\/strong> M\u1ee9c \u0111\u1ed9 d\u1eef li\u1ec7u \u0111\u01b0\u1ee3c chia nh\u1ecf tr\u00ean c\u00e1c b\u1ea3ng \u1ea3nh h\u01b0\u1edfng \u0111\u1ebfn kh\u1ed1i l\u01b0\u1ee3ng d\u1eef li\u1ec7u \u0111\u01b0\u1ee3c qu\u00e9t trong qu\u00e1 tr\u00ecnh truy xu\u1ea5t.<\/li>\n<li><strong>Chi\u1ebfn l\u01b0\u1ee3c l\u1eadp ch\u1ec9 m\u1ee5c:<\/strong> Thi\u1ebft k\u1ebf l\u01b0\u1ee3c \u0111\u1ed3 quy \u0111\u1ecbnh n\u01a1i c\u00e1c ch\u1ec9 m\u1ee5c c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c \u0111\u1eb7t m\u1ed9t c\u00e1ch h\u1ee3p l\u00fd \u0111\u1ec3 h\u1ed7 tr\u1ee3 c\u00e1c m\u1eabu truy v\u1ea5n ph\u1ed5 bi\u1ebfn.<\/li>\n<\/ul>\n<h2>\ud83d\udd0d Nh\u1eadn di\u1ec7n c\u00e1c m\u1eabu c\u1ea5u tr\u00fac ng\u01b0\u1ee3c l\u1ea1i<\/h2>\n<p>Nhi\u1ec1u v\u1ea5n \u0111\u1ec1 hi\u1ec7u su\u1ea5t xu\u1ea5t ph\u00e1t t\u1eeb c\u00e1c m\u1eabu m\u00e0 trong giai \u0111o\u1ea1n thi\u1ebft k\u1ebf ban \u0111\u1ea7u l\u00e0 ch\u1ea5p nh\u1eadn \u0111\u01b0\u1ee3c nh\u01b0ng tr\u1edf th\u00e0nh g\u00e1nh n\u1eb7ng khi kh\u1ed1i l\u01b0\u1ee3ng d\u1eef li\u1ec7u t\u0103ng l\u00ean. Nh\u1eefng m\u1eabu ng\u01b0\u1ee3c l\u1ea1i n\u00e0y th\u01b0\u1eddng xu\u1ea5t hi\u1ec7n tinh t\u1ebf trong s\u01a1 \u0111\u1ed3 nh\u01b0ng g\u00e2y ra s\u1ef1 c\u1ea3n tr\u1edf \u0111\u00e1ng k\u1ec3 trong b\u1ed9 x\u1eed l\u00fd truy v\u1ea5n. D\u01b0\u1edbi \u0111\u00e2y l\u00e0 ph\u00e2n t\u00edch c\u00e1c khuy\u1ebft \u0111i\u1ec3m c\u1ea5u tr\u00fac ph\u1ed5 bi\u1ebfn v\u00e0 t\u00e1c \u0111\u1ed9ng tr\u1ef1c ti\u1ebfp c\u1ee7a ch\u00fang \u0111\u1ebfn t\u1ed1c \u0111\u1ed9.<\/p>\n<table border=\"1\" cellpadding=\"10\" cellspacing=\"0\">\n<tr>\n<th>M\u1eabu ng\u01b0\u1ee3c l\u1ea1i<\/th>\n<th>Ch\u1ec9 b\u00e1o tr\u1ef1c quan trong ERD<\/th>\n<th>T\u00e1c \u0111\u1ed9ng \u0111\u1ebfn hi\u1ec7u su\u1ea5t<\/th>\n<\/tr>\n<tr>\n<td><strong>Thi\u1ebfu kh\u00f3a ngo\u1ea1i<\/strong><\/td>\n<td>C\u00e1c \u0111\u01b0\u1eddng n\u1ed1i gi\u1eefa c\u00e1c b\u1ea3ng m\u00e0 kh\u00f4ng c\u00f3 \u0111\u1ecbnh ngh\u0129a r\u00e0ng bu\u1ed9c.<\/td>\n<td>Cho ph\u00e9p c\u00e1c b\u1ea3n ghi b\u1ecb t\u00e1ch r\u1eddi, bu\u1ed9c c\u00e1c truy v\u1ea5n ph\u1ee9c t\u1ea1p ph\u1ea3i l\u1ecdc d\u1eef li\u1ec7u kh\u00f4ng h\u1ee3p l\u1ec7 m\u1ed9t c\u00e1ch th\u1ee7 c\u00f4ng.<\/td>\n<\/tr>\n<tr>\n<td><strong>Chu\u1ea9n h\u00f3a qu\u00e1 m\u1ee9c<\/strong><\/td>\n<td>S\u1ed1 l\u01b0\u1ee3ng l\u1edbn b\u1ea3ng v\u1edbi c\u00e1c m\u1ed1i quan h\u1ec7 ch\u1ec9 c\u00f3 m\u1ed9t c\u1ed9t.<\/td>\n<td>Y\u00eau c\u1ea7u qu\u00e1 nhi\u1ec1u ph\u00e9p n\u1ed1i \u0111\u1ec3 t\u00e1i t\u1ea1o m\u1ed9t th\u1ef1c th\u1ec3 logic duy nh\u1ea5t, l\u00e0m t\u0103ng s\u1eed d\u1ee5ng CPU.<\/td>\n<\/tr>\n<tr>\n<td><strong>Nhi\u1ec1u-nhi\u1ec1u m\u00e0 kh\u00f4ng c\u00f3 b\u1ea3ng c\u1ea7u n\u1ed1i<\/strong><\/td>\n<td>C\u00e1c \u0111\u01b0\u1eddng m\u1ed1i quan h\u1ec7 nhi\u1ec1u-nhi\u1ec1u tr\u1ef1c ti\u1ebfp gi\u1eefa hai th\u1ef1c th\u1ec3.<\/td>\n<td>C\u00e1c b\u1ed9 \u0111\u1ed9ng c\u01a1 c\u01a1 s\u1edf d\u1eef li\u1ec7u th\u01b0\u1eddng y\u00eau c\u1ea7u m\u1ed9t b\u1ea3ng c\u1ea7u n\u1ed1i; thi\u1ebfu b\u1ea3ng n\u00e0y d\u1eabn \u0111\u1ebfn c\u00e1c gi\u1ea3i ph\u00e1p thay th\u1ebf k\u00e9m hi\u1ec7u qu\u1ea3.<\/td>\n<\/tr>\n<tr>\n<td><strong>Kh\u00f3a ch\u00ednh r\u1ed9ng<\/strong><\/td>\n<td>C\u00e1c kh\u00f3a t\u1ed5ng h\u1ee3p v\u1edbi nhi\u1ec1u c\u1ed9t l\u1edbn.<\/td>\n<td>L\u00e0m t\u0103ng k\u00edch th\u01b0\u1edbc c\u1ee7a t\u1ea5t c\u1ea3 c\u00e1c ch\u1ec9 m\u1ee5c tham chi\u1ebfu \u0111\u1ebfn kh\u00f3a n\u00e0y, l\u00e0m ch\u1eadm thao t\u00e1c tra c\u1ee9u.<\/td>\n<\/tr>\n<tr>\n<td><strong>C\u00e1c c\u1ed9t ch\u1ee9a gi\u00e1 tr\u1ecb r\u1ed7ng<\/strong><\/td>\n<td>C\u00e1c thu\u1ed9c t\u00ednh \u0111\u01b0\u1ee3c \u0111\u00e1nh d\u1ea5u l\u00e0 c\u00f3 th\u1ec3 r\u1ed7ng m\u00e0 kh\u00f4ng c\u00f3 l\u00fd do logic.<\/td>\n<td>C\u00f3 th\u1ec3 ng\u0103n ch\u1eb7n vi\u1ec7c s\u1eed d\u1ee5ng ch\u1ec9 m\u1ee5c ho\u1eb7c l\u00e0m gi\u1ea3m \u0111\u1ed9 ch\u1ecdn l\u1ecdc c\u1ee7a ch\u1ec9 m\u1ee5c, d\u1eabn \u0111\u1ebfn qu\u00e9t to\u00e0n b\u1ed9 b\u1ea3ng.<\/td>\n<\/tr>\n<\/table>\n<h2>\ud83d\udd17 Cardinality quan h\u1ec7 v\u00e0 chi ph\u00ed n\u1ed1i k\u1ebft<\/h2>\n<p>Cardinality x\u00e1c \u0111\u1ecbnh s\u1ed1 l\u01b0\u1ee3ng th\u1ef1c th\u1ec3 c\u1ee7a m\u1ed9t \u0111\u1ed1i t\u01b0\u1ee3ng li\u00ean k\u1ebft v\u1edbi c\u00e1c th\u1ef1c th\u1ec3 c\u1ee7a \u0111\u1ed1i t\u01b0\u1ee3ng kh\u00e1c. \u0110\u00e2y l\u00e0 kh\u00eda c\u1ea1nh quan tr\u1ecdng nh\u1ea5t c\u1ee7a s\u01a1 \u0111\u1ed3 ERD li\u00ean quan \u0111\u1ebfn hi\u1ec7u su\u1ea5t truy v\u1ea5n. C\u00e1c \u0111\u1ecbnh ngh\u0129a cardinality sai s\u1ebd bu\u1ed9c h\u1ec7 th\u1ed1ng ph\u1ea3i x\u1eed l\u00fd nhi\u1ec1u h\u00e0ng h\u01a1n m\u1ee9c c\u1ea7n thi\u1ebft \u0111\u1ec3 \u0111\u00e1p \u1ee9ng m\u1ed9t truy v\u1ea5n.<\/p>\n<p>Khi kh\u1eafc ph\u1ee5c c\u00e1c truy v\u1ea5n ch\u1eadm, b\u1ea1n ph\u1ea3i x\u00e1c minh r\u1eb1ng c\u00e1c m\u1ed1i quan h\u1ec7 trong s\u01a1 \u0111\u1ed3 ph\u00f9 h\u1ee3p v\u1edbi y\u00eau c\u1ea7u logic c\u1ee7a \u1ee9ng d\u1ee5ng. N\u1ebfu m\u1ed9t m\u1ed1i quan h\u1ec7 \u0111\u01b0\u1ee3c \u0111\u1ecbnh ngh\u0129a l\u00e0 Nhi\u1ec1u-\u0110a m\u00e0 th\u1ef1c t\u1ebf ph\u1ea3i l\u00e0 M\u1ed9t-\u0110a, b\u1ed9 x\u1eed l\u00fd truy v\u1ea5n s\u1ebd chu\u1ea9n b\u1ecb cho vi\u1ec7c n\u1ed1i qua b\u1ea3ng li\u00ean k\u1ebft c\u00f3 th\u1ec3 kh\u00f4ng t\u1ed3n t\u1ea1i ho\u1eb7c \u0111\u01b0\u1ee3c \u0111i\u1ec1n d\u1eef li\u1ec7u m\u1ed9t c\u00e1ch kh\u00f4ng hi\u1ec7u qu\u1ea3.<\/p>\n<h3>C\u00e1c v\u1ea5n \u0111\u1ec1 ph\u1ed5 bi\u1ebfn v\u1ec1 cardinality<\/h3>\n<ul>\n<li><strong>Cardinality ch\u01b0a \u0111\u01b0\u1ee3c x\u00e1c \u0111\u1ecbnh:<\/strong>N\u1ebfu s\u01a1 \u0111\u1ed3 kh\u00f4ng x\u00e1c \u0111\u1ecbnh m\u1ed1i quan h\u1ec7 l\u00e0 b\u1eaft bu\u1ed9c hay t\u00f9y ch\u1ecdn, b\u1ed9 t\u1ed1i \u01b0u truy v\u1ea5n c\u00f3 th\u1ec3 gi\u1ea3 \u0111\u1ecbnh t\u00ecnh hu\u1ed1ng x\u1ea5u nh\u1ea5t, th\u00eam c\u00e1c ki\u1ec3m tra b\u1ed5 sung cho gi\u00e1 tr\u1ecb r\u1ed7ng.<\/li>\n<li><strong>C\u00e1c m\u1ed1i quan h\u1ec7 \u0111\u1ec7 quy:<\/strong>C\u00e1c b\u1ea3ng tham chi\u1ebfu ch\u00ednh m\u00ecnh (v\u00ed d\u1ee5: b\u1ea3ng Nh\u00e2n vi\u00ean tham chi\u1ebfu ch\u00ednh n\u00f3 \u0111\u1ec3 x\u00e1c \u0111\u1ecbnh Qu\u1ea3n l\u00fd) c\u00f3 th\u1ec3 g\u00e2y ra s\u1ef1 l\u1ed3ng gh\u00e9p s\u00e2u trong truy v\u1ea5n. Kh\u00f4ng c\u00f3 ch\u1ec9 m\u1ee5c ph\u00f9 h\u1ee3p tr\u00ean c\u1ed9t tham chi\u1ebfu ch\u00ednh m\u00ecnh, c\u00e1c truy v\u1ea5n n\u00e0y s\u1ebd tr\u1edf n\u00ean ch\u1eadm h\u01a1n theo c\u1ea5p s\u1ed1 nh\u00e2n.<\/li>\n<li><strong>C\u00e1c ph\u1ee5 thu\u1ed9c v\u00f2ng:<\/strong>Nh\u1eefng m\u1ea1ng l\u01b0\u1edbi quan h\u1ec7 ph\u1ee9c t\u1ea1p n\u01a1i B\u1ea3ng A li\u00ean k\u1ebft v\u1edbi B, B li\u00ean k\u1ebft v\u1edbi C, v\u00e0 C quay l\u1ea1i li\u00ean k\u1ebft v\u1edbi A. C\u1ea5u tr\u00fac n\u00e0y khi\u1ebfn vi\u1ec7c duy\u1ec7t \u0111\u1ed3 th\u1ecb d\u1eef li\u1ec7u tr\u1edf n\u00ean kh\u00f3 kh\u0103n \u0111\u1ed1i v\u1edbi b\u1ed9 x\u1eed l\u00fd, th\u01b0\u1eddng d\u1eabn \u0111\u1ebfn vi\u1ec7c t\u1ea1o c\u00e1c b\u1ea3ng t\u1ea1m trong b\u1ed9 nh\u1edb.<\/li>\n<\/ul>\n<p>\u0110\u1ec3 gi\u1ea3m thi\u1ec3u c\u00e1c v\u1ea5n \u0111\u1ec1 n\u00e0y, h\u00e3y \u0111\u1ea3m b\u1ea3o s\u01a1 \u0111\u1ed3 ERD ph\u00e2n bi\u1ec7t r\u00f5 r\u00e0ng gi\u1eefa c\u00e1c li\u00ean k\u1ebft t\u00f9y ch\u1ecdn v\u00e0 b\u1eaft bu\u1ed9c. C\u00e1c li\u00ean k\u1ebft b\u1eaft bu\u1ed9c cho ph\u00e9p b\u1ed9 t\u1ed1i \u01b0u b\u1ecf qua ki\u1ec3m tra gi\u00e1 tr\u1ecb r\u1ed7ng, t\u1eeb \u0111\u00f3 c\u1ea3i thi\u1ec7n t\u1ed1c \u0111\u1ed9 th\u1ef1c thi. C\u00e1c li\u00ean k\u1ebft t\u00f9y ch\u1ecdn y\u00eau c\u1ea7u th\u00eam logic \u0111\u1ec3 x\u1eed l\u00fd c\u00e1c tr\u01b0\u1eddng h\u1ee3p m\u1ed1i quan h\u1ec7 kh\u00f4ng t\u1ed3n t\u1ea1i.<\/p>\n<h2>\ud83d\udccf Ki\u1ec3u d\u1eef li\u1ec7u v\u00e0 hi\u1ec7u qu\u1ea3 l\u01b0u tr\u1eef<\/h2>\n<p>Vi\u1ec7c l\u1ef1a ch\u1ecdn ki\u1ec3u d\u1eef li\u1ec7u trong \u0111\u1ecbnh ngh\u0129a s\u01a1 \u0111\u1ed3 c\u00f3 \u1ea3nh h\u01b0\u1edfng s\u00e2u s\u1eafc \u0111\u1ebfn k\u00edch th\u01b0\u1edbc l\u01b0u tr\u1eef v\u00e0 t\u1ed1c \u0111\u1ed9 so s\u00e1nh. M\u1ed9t truy v\u1ea5n so s\u00e1nh hai c\u1ed9t c\u00f3 ki\u1ec3u kh\u00e1c nhau th\u01b0\u1eddng k\u00edch ho\u1ea1t chuy\u1ec3n \u0111\u1ed5i ng\u1ea7m. Nh\u1eefng chuy\u1ec3n \u0111\u1ed5i n\u00e0y ng\u0103n c\u1ea3n vi\u1ec7c s\u1eed d\u1ee5ng ch\u1ec9 m\u1ee5c v\u00e0 bu\u1ed9c b\u1ed9 x\u1eed l\u00fd ph\u1ea3i x\u1eed l\u00fd t\u1eebng h\u00e0ng.<\/p>\n<h3>H\u1ec7 qu\u1ea3 v\u1ec1 l\u01b0u tr\u1eef<\/h3>\n<p>Khi s\u01a1 \u0111\u1ed3 s\u1eed d\u1ee5ng ki\u1ec3u d\u1eef li\u1ec7u chung cho t\u1ea5t c\u1ea3 c\u00e1c c\u1ed9t, ch\u1eb3ng h\u1ea1n nh\u01b0 tr\u01b0\u1eddng v\u0103n b\u1ea3n l\u1edbn cho c\u00e1c m\u00e3 ng\u1eafn, n\u00f3 s\u1ebd ti\u00eau t\u1ed1n nhi\u1ec1u kh\u00f4ng gian \u0111\u0129a v\u00e0 b\u1ed9 nh\u1edb. \u0110i\u1ec1u n\u00e0y l\u00e0m gi\u1ea3m k\u00edch th\u01b0\u1edbc hi\u1ec7u qu\u1ea3 c\u1ee7a b\u1ed9 \u0111\u1ec7m, ngh\u0129a l\u00e0 \u00edt trang d\u1eef li\u1ec7u n\u00f3ng h\u01a1n c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c gi\u1eef trong b\u1ed9 nh\u1edb. K\u1ebft qu\u1ea3 l\u00e0 h\u1ec7 th\u1ed1ng ph\u1ea3i \u0111\u1ecdc nhi\u1ec1u d\u1eef li\u1ec7u h\u01a1n t\u1eeb h\u1ec7 th\u1ed1ng \u0111\u0129a ch\u1eadm h\u01a1n.<\/p>\n<h3>Hi\u1ec7u su\u1ea5t so s\u00e1nh<\/h3>\n<p>So s\u00e1nh s\u1ed1 nguy\u00ean nhanh h\u01a1n \u0111\u00e1ng k\u1ec3 so v\u1edbi so s\u00e1nh chu\u1ed7i. N\u1ebfu s\u01a1 \u0111\u1ed3 ERD \u0111\u1ecbnh ngh\u0129a kh\u00f3a ngo\u1ea1i l\u00e0 ki\u1ec3u chu\u1ed7i (v\u00ed d\u1ee5: VARCHAR) thay v\u00ec ki\u1ec3u s\u1ed1 nguy\u00ean (v\u00ed d\u1ee5: INT), thao t\u00e1c n\u1ed1i s\u1ebd ph\u1ea3i so s\u00e1nh t\u1eebng k\u00fd t\u1ef1 thay v\u00ec s\u1eed d\u1ee5ng so s\u00e1nh s\u1ed1 nh\u1ecb ph\u00e2n. \u0110i\u1ec1u n\u00e0y l\u00e0m t\u0103ng s\u1ed1 v\u00f2ng x\u1eed l\u00fd CPU cho m\u1ed7i h\u00e0ng \u0111\u01b0\u1ee3c x\u1eed l\u00fd.<\/p>\n<ul>\n<li><strong>S\u1eed d\u1ee5ng ki\u1ec3u d\u1eef li\u1ec7u c\u00f3 \u0111\u1ed9 d\u00e0i c\u1ed1 \u0111\u1ecbnh:<\/strong> \u0110\u1ed1i v\u1edbi c\u00e1c tr\u01b0\u1eddng nh\u01b0 m\u00e3 qu\u1ed1c gia ho\u1eb7c c\u1edd tr\u1ea1ng th\u00e1i, h\u00e3y s\u1eed d\u1ee5ng chu\u1ed7i c\u00f3 \u0111\u1ed9 d\u00e0i c\u1ed1 \u0111\u1ecbnh. Chu\u1ed7i c\u00f3 \u0111\u1ed9 d\u00e0i thay \u0111\u1ed5i s\u1ebd g\u00e2y th\u00eam chi ph\u00ed \u0111\u1ec3 t\u00ednh \u0111\u1ed9 d\u00e0i m\u1ed7i l\u1ea7n \u0111\u1ecdc.<\/li>\n<li><strong>Tr\u00e1nh s\u1eed d\u1ee5ng v\u0103n b\u1ea3n d\u00e0i trong kh\u00f3a:<\/strong> Kh\u00f4ng bao gi\u1edd s\u1eed d\u1ee5ng c\u1ed9t ch\u1ee9a nhi\u1ec1u v\u0103n b\u1ea3n l\u00e0m kh\u00f3a ch\u00ednh ho\u1eb7c kh\u00f3a ngo\u1ea1i. \u0110i\u1ec1u n\u00e0y l\u00e0m t\u0103ng k\u00edch th\u01b0\u1edbc c\u1ee7a m\u1ecdi ch\u1ec9 m\u1ee5c tham chi\u1ebfu \u0111\u1ebfn n\u00f3.<\/li>\n<li><strong>\u0110\u1ea3m b\u1ea3o ki\u1ec3u d\u1eef li\u1ec7u c\u1ee7a b\u1ea3ng con kh\u1edbp v\u1edbi b\u1ea3ng cha:<\/strong> \u0110\u1ea3m b\u1ea3o ki\u1ec3u d\u1eef li\u1ec7u trong b\u1ea3ng con kh\u1edbp ch\u00ednh x\u00e1c v\u1edbi b\u1ea3ng cha. Ngay c\u1ea3 m\u1ed9t s\u1ef1 kh\u00e1c bi\u1ec7t nh\u1ecf (v\u00ed d\u1ee5: INT so v\u1edbi BIGINT) c\u0169ng c\u00f3 th\u1ec3 bu\u1ed9c ph\u1ea3i chuy\u1ec3n \u0111\u1ed5i trong qu\u00e1 tr\u00ecnh n\u1ed1i.<\/li>\n<\/ul>\n<h2>\ud83d\udd11 T\u00ednh minh b\u1ea1ch v\u00e0 chi\u1ebfn l\u01b0\u1ee3c l\u1eadp ch\u1ec9 m\u1ee5c<\/h2>\n<p>S\u01a1 \u0111\u1ed3 ERD l\u00e0 bi\u1ec3u di\u1ec5n tr\u1ef1c quan c\u1ee7a c\u1ea5u tr\u00fac logic, nh\u01b0ng n\u00f3 c\u0169ng n\u00ean \u0111\u1ecbnh h\u01b0\u1edbng chi\u1ebfn l\u01b0\u1ee3c ch\u1ec9 m\u1ee5c v\u1eadt l\u00fd. M\u1eb7c d\u00f9 c\u00e1c ch\u1ec9 m\u1ee5c th\u01b0\u1eddng \u0111\u01b0\u1ee3c th\u00eam sau khi x\u00e2y d\u1ef1ng s\u01a1 \u0111\u1ed3, giai \u0111o\u1ea1n thi\u1ebft k\u1ebf c\u1ea7n d\u1ef1 \u0111o\u00e1n n\u01a1i n\u00e0o c\u1ea7n ch\u1ec9 m\u1ee5c. M\u1ed9t truy v\u1ea5n l\u1ecdc theo c\u1ed9t kh\u00f4ng \u0111\u01b0\u1ee3c ch\u1ec9 m\u1ee5c l\u00e0 d\u1ea5u hi\u1ec7u ch\u00ednh c\u1ee7a kho\u1ea3ng tr\u1ed1ng thi\u1ebft k\u1ebf.<\/p>\n<h3>C\u01a1 h\u1ed9i l\u1eadp ch\u1ec9 m\u1ee5c trong s\u01a1 \u0111\u1ed3 ERD<\/h3>\n<p>Khi xem x\u00e9t s\u01a1 \u0111\u1ed3 \u0111\u1ec3 t\u00ecm c\u00e1c \u0111i\u1ec3m ngh\u1ebdn hi\u1ec7u su\u1ea5t, h\u00e3y t\u00ecm c\u00e1c c\u1ed9t th\u01b0\u1eddng xuy\u00ean \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng trong \u0111i\u1ec1u ki\u1ec7n t\u00ecm ki\u1ebfm ho\u1eb7c tham gia n\u1ed1i k\u1ebft.<\/p>\n<ul>\n<li><strong>Kh\u00f3a ngo\u1ea1i:<\/strong> Ch\u00fang h\u1ea7u nh\u01b0 lu\u00f4n ph\u1ea3i \u0111\u01b0\u1ee3c l\u1eadp ch\u1ec9 m\u1ee5c. N\u1ebfu m\u1ed9t truy v\u1ea5n n\u1ed1i Table A v\u1edbi Table B th\u00f4ng qua kh\u00f3a ngo\u1ea1i, v\u00e0 kh\u00f3a \u1edf Table B kh\u00f4ng \u0111\u01b0\u1ee3c l\u1eadp ch\u1ec9 m\u1ee5c, th\u00ec b\u1ed9 x\u1eed l\u00fd ph\u1ea3i qu\u00e9t to\u00e0n b\u1ed9 Table B cho m\u1ed7i h\u00e0ng trong Table A.<\/li>\n<li><strong>C\u1edd tr\u1ea1ng th\u00e1i:<\/strong> C\u00e1c c\u1ed9t x\u00e1c \u0111\u1ecbnh tr\u1ea1ng th\u00e1i c\u1ee7a m\u1ed9t b\u1ea3n ghi (v\u00ed d\u1ee5: Is_Active, Order_Status) th\u01b0\u1eddng \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng trong c\u00e1c m\u1ec7nh \u0111\u1ec1 WHERE. N\u1ebfu c\u00e1c c\u1ed9t n\u00e0y kh\u00f4ng \u0111\u01b0\u1ee3c l\u1eadp ch\u1ec9 m\u1ee5c, vi\u1ec7c l\u1ecdc s\u1ebd tr\u1edf th\u00e0nh qu\u00e9t to\u00e0n b\u1ed9 b\u1ea3ng.<\/li>\n<li><strong>Kho\u1ea3ng ng\u00e0y th\u00e1ng:<\/strong> C\u00e1c b\u1ea3ng c\u00f3 nh\u1eadt k\u00fd ki\u1ec3m to\u00e1n ho\u1eb7c nh\u1eadt k\u00fd giao d\u1ecbch th\u01b0\u1eddng truy v\u1ea5n theo ng\u00e0y. C\u1ed9t ng\u00e0y n\u00ean \u0111\u01b0\u1ee3c l\u1eadp ch\u1ec9 m\u1ee5c \u0111\u1ec3 cho ph\u00e9p qu\u00e9t ph\u1ea1m vi hi\u1ec7u qu\u1ea3.<\/li>\n<\/ul>\n<p> Vi\u1ec7c c\u00e2n b\u1eb1ng s\u1ed1 l\u01b0\u1ee3ng ch\u1ec9 m\u1ee5c v\u1edbi hi\u1ec7u su\u1ea5t ghi l\u00e0 \u0111i\u1ec1u r\u1ea5t quan tr\u1ecdng. M\u1ed7i ch\u1ec9 m\u1ee5c \u0111\u1ec1u l\u00e0m t\u0103ng chi ph\u00ed cho c\u00e1c thao t\u00e1c INSERT, UPDATE v\u00e0 DELETE. Tuy nhi\u00ean, m\u1ed9t l\u01b0\u1ee3c \u0111\u1ed3 \u0111\u1ecdc nhi\u1ec1u nh\u01b0ng \u0111\u01b0\u1ee3c ch\u1ec9 m\u1ee5c k\u00e9m s\u1ebd g\u00e2y ra \u0111\u1ed9 tr\u1ec5 h\u1ec7 th\u1ed1ng l\u1edbn h\u01a1n chi ph\u00ed ghi. S\u01a1 \u0111\u1ed3 ERD gi\u00fap h\u00ecnh dung r\u00f5 r\u00e0ng c\u00e1c b\u1ea3ng n\u00e0o l\u00e0 \u0111\u1ecdc nhi\u1ec1u (v\u00ed d\u1ee5: b\u1ea3ng tra c\u1ee9u) so v\u1edbi c\u00e1c b\u1ea3ng ghi nhi\u1ec1u (v\u00ed d\u1ee5: nh\u1eadt k\u00fd giao d\u1ecbch), t\u1eeb \u0111\u00f3 \u0111\u1ecbnh h\u01b0\u1edbng quy\u1ebft \u0111\u1ecbnh l\u1eadp ch\u1ec9 m\u1ee5c.<\/p>\n<h2>\ud83d\udeab B\u1ec7nh l\u00fd n\u1ed1i k\u1ebft<\/h2>\n<p>M\u1ed9t trong nh\u1eefng nguy\u00ean nh\u00e2n ph\u1ed5 bi\u1ebfn nh\u1ea5t g\u00e2y ra c\u00e1c truy v\u1ea5n ch\u1eadm l\u00e0 \u0111\u01b0\u1eddng n\u1ed1i k\u1ebft. \u0110i\u1ec1u n\u00e0y \u00e1m ch\u1ec9 \u0111\u1ebfn th\u1ee9 t\u1ef1 m\u00e0 b\u1ed9 x\u1eed l\u00fd c\u01a1 s\u1edf d\u1eef li\u1ec7u k\u1ebft n\u1ed1i c\u00e1c b\u1ea3ng \u0111\u1ec3 \u0111\u00e1p \u1ee9ng m\u1ed9t y\u00eau c\u1ea7u. M\u1ed9t l\u01b0\u1ee3c \u0111\u1ed3 \u0111\u01b0\u1ee3c thi\u1ebft k\u1ebf k\u00e9m c\u00f3 th\u1ec3 bu\u1ed9c b\u1ed9 x\u1eed l\u00fd \u0111i v\u00e0o m\u1ed9t con \u0111\u01b0\u1eddng h\u1ee3p l\u00fd v\u1ec1 m\u1eb7t logic nh\u01b0ng t\u1ed1n k\u00e9m v\u1ec1 m\u1eb7t t\u00ednh to\u00e1n.<\/p>\n<h3>T\u00edch \u0110\u1ec1-c\u00e1c<\/h3>\n<p>N\u1ebfu l\u01b0\u1ee3c \u0111\u1ed3 thi\u1ebfu c\u00e1c r\u00e0ng bu\u1ed9c ph\u00f9 h\u1ee3p ho\u1eb7c n\u1ebfu logic truy v\u1ea5n kh\u00f4ng x\u00e1c \u0111\u1ecbnh \u0111\u00fang \u0111i\u1ec1u ki\u1ec7n n\u1ed1i k\u1ebft, b\u1ed9 x\u1eed l\u00fd c\u00f3 th\u1ec3 t\u1ea1o ra t\u00edch \u0110\u1ec1-c\u00e1c. \u0110i\u1ec1u n\u00e0y x\u1ea3y ra khi m\u1ed7i h\u00e0ng trong Table A \u0111\u01b0\u1ee3c k\u1ebft h\u1ee3p v\u1edbi m\u1ed7i h\u00e0ng trong Table B. T\u1eadp k\u1ebft qu\u1ea3 t\u0103ng theo c\u1ea5p s\u1ed1 nh\u00e2n, v\u00e0 truy v\u1ea5n c\u00f3 th\u1ec3 h\u1ebft th\u1eddi gian ho\u1eb7c ti\u00eau th\u1ee5 to\u00e0n b\u1ed9 b\u1ed9 nh\u1edb s\u1eb5n c\u00f3.<\/p>\n<p>Trong s\u01a1 \u0111\u1ed3 ERD, \u0111i\u1ec1u n\u00e0y th\u01b0\u1eddng x\u1ea3y ra khi m\u1ed1i quan h\u1ec7 Nhi\u1ec1u-\u0110a kh\u00f4ng \u0111\u01b0\u1ee3c \u0111i\u1ec1u ti\u1ebft \u0111\u00fang c\u00e1ch b\u1edfi m\u1ed9t b\u1ea3ng trung gian, ho\u1eb7c khi b\u1ea3ng trung gian thi\u1ebfu c\u00e1c r\u00e0ng bu\u1ed9c kh\u00f3a ngo\u1ea1i c\u1ea7n thi\u1ebft.<\/p>\n<h3>Truy v\u1ea5n con so v\u1edbi n\u1ed1i k\u1ebft<\/h3>\n<p>Thi\u1ebft k\u1ebf l\u01b0\u1ee3c \u0111\u1ed3 \u1ea3nh h\u01b0\u1edfng \u0111\u1ebfn vi\u1ec7c m\u1ed9t truy v\u1ea5n c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c th\u1ef1c thi nh\u01b0 m\u1ed9t n\u1ed1i k\u1ebft \u0111\u01a1n gi\u1ea3n hay c\u1ea7n \u0111\u1ebfn truy v\u1ea5n con. Truy v\u1ea5n con th\u01b0\u1eddng th\u1ef1c thi truy v\u1ea5n b\u00ean trong m\u1ed9t l\u1ea7n cho m\u1ed7i h\u00e0ng c\u1ee7a truy v\u1ea5n b\u00ean ngo\u00e0i, d\u1eabn \u0111\u1ebfn \u0111\u1ed9 ph\u1ee9c t\u1ea1p th\u1eddi gian b\u1eadc hai. M\u1ed9t l\u01b0\u1ee3c \u0111\u1ed3 chu\u1ea9n h\u00f3a cho ph\u00e9p n\u1ed1i k\u1ebft tr\u1ef1c ti\u1ebfp th\u01b0\u1eddng \u0111\u01b0\u1ee3c \u01b0u ti\u00ean h\u01a1n so v\u1edbi c\u00e1c c\u1ea5u tr\u00fac kh\u00f4ng chu\u1ea9n h\u00f3a bu\u1ed9c ph\u1ea3i d\u00f9ng truy v\u1ea5n con.<\/p>\n<h2>\u2705 Danh s\u00e1ch ki\u1ec3m tra x\u00e1c th\u1ef1c l\u01b0\u1ee3c \u0111\u1ed3<\/h2>\n<p>\u0110\u1ec3 kh\u1eafc ph\u1ee5c c\u00e1c truy v\u1ea5n ch\u1eadm m\u1ed9t c\u00e1ch h\u1ec7 th\u1ed1ng d\u1ef1a tr\u00ean ERD, h\u00e3y th\u1ef1c hi\u1ec7n \u0111\u00e1nh gi\u00e1 c\u00f3 c\u1ea5u tr\u00fac. Danh s\u00e1ch ki\u1ec3m tra n\u00e0y \u0111\u1ea3m b\u1ea3o b\u1ea1n xem x\u00e9t m\u1ecdi th\u00e0nh ph\u1ea7n quan tr\u1ecdng trong thi\u1ebft k\u1ebf.<\/p>\n<h3>1. Xem x\u00e9t c\u00e1c r\u00e0ng bu\u1ed9c kh\u00f3a ngo\u1ea1i<\/h3>\n<ul>\n<li>T\u1ea5t c\u1ea3 c\u00e1c kh\u00f3a ngo\u1ea1i c\u00f3 \u0111\u01b0\u1ee3c x\u00e1c \u0111\u1ecbnh r\u00f5 r\u00e0ng trong s\u01a1 \u0111\u1ed3 kh\u00f4ng?<\/li>\n<li>Ch\u00fang c\u00f3 bao g\u1ed3m c\u00e1c quy t\u1eafc lan truy\u1ec1n c\u00f3 th\u1ec3 g\u00e2y ra di chuy\u1ec3n d\u1eef li\u1ec7u kh\u00f4ng mong mu\u1ed1n kh\u00f4ng?<\/li>\n<li>Ki\u1ec3u d\u1eef li\u1ec7u \u1edf hai ph\u00eda c\u1ee7a m\u1ed1i quan h\u1ec7 c\u00f3 gi\u1ed1ng nhau kh\u00f4ng?<\/li>\n<\/ul>\n<h3>2. Ph\u00e2n t\u00edch t\u1ea7n su\u1ea5t n\u1ed1i k\u1ebft<\/h3>\n<ul>\n<li>X\u00e1c \u0111\u1ecbnh c\u00e1c b\u1ea3ng th\u01b0\u1eddng \u0111\u01b0\u1ee3c n\u1ed1i k\u1ebft v\u1edbi nhau nh\u1ea5t trong logic \u1ee9ng d\u1ee5ng.<\/li>\n<li>C\u00e1c b\u1ea3ng n\u00e0y c\u00f3 k\u1ec1 nhau trong s\u01a1 \u0111\u1ed3, hay \u0111\u01b0\u1eddng \u0111i y\u00eau c\u1ea7u \u0111i qua nhi\u1ec1u b\u1ea3ng trung gian?<\/li>\n<li>C\u00f3 th\u1ec3 h\u1ee3p nh\u1ea5t b\u1ea5t k\u1ef3 b\u1ea3ng trung gian n\u00e0o trong s\u1ed1 n\u00e0y \u0111\u1ec3 gi\u1ea3m \u0111\u1ed9 s\u00e2u n\u1ed1i k\u1ebft kh\u00f4ng?<\/li>\n<\/ul>\n<h3>3. Ki\u1ec3m tra kh\u1ea3 n\u0103ng ch\u1ea5p nh\u1eadn gi\u00e1 tr\u1ecb NULL<\/h3>\n<ul>\n<li>C\u00e1c c\u1ed9t kh\u00f4ng bao gi\u1edd c\u00f3 gi\u00e1 tr\u1ecb NULL c\u00f3 \u0111\u01b0\u1ee3c \u0111\u00e1nh d\u1ea5u r\u00f5 r\u00e0ng l\u00e0 NOT NULL kh\u00f4ng?<\/li>\n<li>L\u01b0\u1ee3c \u0111\u1ed3 c\u00f3 cho ph\u00e9p NULL tr\u00ean c\u00e1c c\u1ed9t n\u1eb1m trong ch\u1ec9 m\u1ee5c kh\u00f4ng?<\/li>\n<\/ul>\n<h3>4. X\u00e1c minh ki\u1ec3u d\u1eef li\u1ec7u<\/h3>\n<ul>\n<li>C\u00e1c tr\u01b0\u1eddng s\u1ed1 li\u1ec7u c\u00f3 \u0111ang s\u1eed d\u1ee5ng k\u00edch th\u01b0\u1edbc nh\u1ecf nh\u1ea5t ph\u00f9 h\u1ee3p (v\u00ed d\u1ee5: TINYINT so v\u1edbi BIGINT)?<\/li>\n<li>C\u00e1c tr\u01b0\u1eddng v\u0103n b\u1ea3n c\u00f3 \u0111ang s\u1eed d\u1ee5ng \u0111\u1ed9 d\u00e0i \u0111\u00fang \u0111\u1ec3 tr\u00e1nh b\u1ecb c\u1eaft ng\u1eafn ho\u1eb7c l\u01b0u tr\u1eef th\u1eeba?<\/li>\n<\/ul>\n<h3>5. \u0110\u00e1nh gi\u00e1 ph\u1ea1m vi ch\u1ec9 m\u1ee5c<\/h3>\n<ul>\n<li>C\u00e1c kh\u00f3a ch\u00ednh v\u00e0 kh\u00f3a ngo\u1ea1i c\u00f3 c\u00f3 ch\u1ec9 m\u1ee5c kh\u00f4ng?<\/li>\n<li>C\u00e1c c\u1ed9t th\u01b0\u1eddng xuy\u00ean \u0111\u01b0\u1ee3c l\u1ecdc c\u00f3 \u0111\u01b0\u1ee3c ch\u1ec9 m\u1ee5c h\u00f3a kh\u00f4ng?<\/li>\n<li>C\u00f3 ch\u1ec9 m\u1ee5c k\u1ebft h\u1ee3p cho c\u00e1c truy v\u1ea5n \u0111a c\u1ed9t ph\u1ed5 bi\u1ebfn kh\u00f4ng?<\/li>\n<\/ul>\n<h2>\ud83d\udee0\ufe0f C\u00e1c b\u01b0\u1edbc th\u1ef1c t\u1ebf \u0111\u1ec3 kh\u1eafc ph\u1ee5c<\/h2>\n<p>Sau khi s\u01a1 \u0111\u1ed3 ERD \u0111\u00e3 \u0111\u01b0\u1ee3c ph\u00e2n t\u00edch v\u00e0 ph\u00e1t hi\u1ec7n c\u00e1c v\u1ea5n \u0111\u1ec1, giai \u0111o\u1ea1n ti\u1ebfp theo l\u00e0 kh\u1eafc ph\u1ee5c. \u0110i\u1ec1u n\u00e0y bao g\u1ed3m vi\u1ec7c thay \u0111\u1ed5i c\u1ea5u tr\u00fac \u0111\u1ec3 ph\u00f9 h\u1ee3p v\u1edbi y\u00eau c\u1ea7u hi\u1ec7u su\u1ea5t m\u00e0 kh\u00f4ng l\u00e0m t\u1ed5n h\u1ea1i \u0111\u1ebfn t\u00ednh to\u00e0n v\u1eb9n d\u1eef li\u1ec7u.<\/p>\n<p><strong>Tinh ch\u1ec9nh c\u00e1c m\u1ed1i quan h\u1ec7:<\/strong> N\u1ebfu s\u01a1 \u0111\u1ed3 ERD cho th\u1ea5y c\u00e1c m\u1ed1i quan h\u1ec7 qu\u00e1 ph\u1ee9c t\u1ea1p, h\u00e3y c\u00e2n nh\u1eafc \u0111\u01a1n gi\u1ea3n h\u00f3a ch\u00fang. \u0110i\u1ec1u n\u00e0y c\u00f3 th\u1ec3 c\u00f3 ngh\u0129a l\u00e0 \u00e1p d\u1ee5ng thay \u0111\u1ed5i kh\u00f4ng chu\u1ea9n h\u00f3a \u1edf m\u1ed9t s\u1ed1 khu v\u1ef1c c\u1ee5 th\u1ec3, c\u00f3 nhi\u1ec1u truy v\u1ea5n \u0111\u1ecdc, nh\u1eb1m gi\u1ea3m nhu c\u1ea7u th\u1ef1c hi\u1ec7n c\u00e1c thao t\u00e1c n\u1ed1i. V\u00ed d\u1ee5, l\u01b0u tr\u1eef s\u1ed1 l\u01b0\u1ee3ng \u0111\u00e3 \u0111\u01b0\u1ee3c l\u01b0u t\u1ea1m c\u1ee7a c\u00e1c m\u1ee5c li\u00ean quan trong b\u1ea3ng cha c\u00f3 th\u1ec3 lo\u1ea1i b\u1ecf nhu c\u1ea7u n\u1ed1i v\u00e0 \u0111\u1ebfm m\u1ed7i l\u1ea7n.<\/p>\n<p><strong>T\u1ed1i \u01b0u h\u00f3a ki\u1ec3u d\u1eef li\u1ec7u:<\/strong> Thay \u0111\u1ed5i ki\u1ec3u d\u1eef li\u1ec7u th\u00e0nh c\u00e1c l\u1ef1a ch\u1ecdn hi\u1ec7u qu\u1ea3 h\u01a1n. N\u1ebfu m\u1ed9t ng\u00e0y ch\u1ec9 \u0111\u01b0\u1ee3c l\u01b0u theo ng\u00e0y, h\u00e3y s\u1eed d\u1ee5ng ki\u1ec3u d\u1eef li\u1ec7u ch\u1ec9 c\u00f3 ng\u00e0y thay v\u00ec ki\u1ec3u datetime c\u00f3 th\u1eddi gian. N\u1ebfu m\u1ed9t ID l\u00e0 s\u1ed1, h\u00e3y \u0111\u1ea3m b\u1ea3o n\u00f3 kh\u00f4ng \u0111\u01b0\u1ee3c l\u01b0u d\u01b0\u1edbi d\u1ea1ng chu\u1ed7i.<\/p>\n<p><strong>Th\u1ef1c hi\u1ec7n chia t\u00e1ch d\u1eef li\u1ec7u:<\/strong> \u0110\u1ed1i v\u1edbi c\u00e1c b\u1ea3ng r\u1ea5t l\u1edbn, s\u01a1 \u0111\u1ed3 ERD c\u00f3 th\u1ec3 c\u1ea7n ph\u1ea3n \u00e1nh chi\u1ebfn l\u01b0\u1ee3c chia t\u00e1ch d\u1eef li\u1ec7u. M\u1eb7c d\u00f9 chia t\u00e1ch d\u1eef li\u1ec7u th\u01b0\u1eddng l\u00e0 chi ti\u1ebft tri\u1ec3n khai v\u1eadt l\u00fd, thi\u1ebft k\u1ebf logic c\u1ea7n t\u00ednh \u0111\u1ebfn c\u00e1ch d\u1eef li\u1ec7u \u0111\u01b0\u1ee3c nh\u00f3m l\u1ea1i. Chia t\u00e1ch theo ng\u00e0y ho\u1eb7c khu v\u1ef1c c\u00f3 th\u1ec3 gi\u00fap h\u1ec7 th\u1ed1ng ch\u1ec9 qu\u00e9t nh\u1eefng \u0111o\u1ea1n d\u1eef li\u1ec7u li\u00ean quan.<\/p>\n<h2>\ud83d\udd0e Nh\u1eefng c\u00e2n nh\u1eafc cu\u1ed1i c\u00f9ng<\/h2>\n<p>Kh\u1eafc ph\u1ee5c s\u1ef1 c\u1ed1 hi\u1ec7u su\u1ea5t l\u00e0 m\u1ed9t qu\u00e1 tr\u00ecnh l\u1eb7p l\u1ea1i. S\u01a1 \u0111\u1ed3 ERD \u0111\u00f3ng vai tr\u00f2 l\u00e0 t\u00e0i li\u1ec7u trung t\u00e2m trong qu\u00e1 tr\u00ecnh n\u00e0y. B\u1eb1ng c\u00e1ch coi s\u01a1 \u0111\u1ed3 nh\u01b0 m\u1ed9t t\u00e0i li\u1ec7u s\u1ed1ng, ph\u1ea3n \u00e1nh c\u1ea3 c\u1ea5u tr\u00fac logic v\u00e0 c\u00e1c r\u00e0ng bu\u1ed9c hi\u1ec7u su\u1ea5t v\u1eadt l\u00fd, b\u1ea1n c\u00f3 th\u1ec3 duy tr\u00ec m\u1ed9t h\u1ec7 th\u1ed1ng c\u01a1 s\u1edf d\u1eef li\u1ec7u v\u1eabn ph\u1ea3n h\u1ed3i t\u1ed1t khi d\u1eef li\u1ec7u t\u0103ng l\u00ean.<\/p>\n<p>H\u00e3y nh\u1edb r\u1eb1ng kh\u00f4ng c\u00f3 thi\u1ebft k\u1ebf n\u00e0o ph\u00f9 h\u1ee3p v\u1edbi m\u1ecdi t\u00ecnh hu\u1ed1ng. M\u1ed9t l\u01b0\u1ee3c \u0111\u1ed3 \u0111\u01b0\u1ee3c t\u1ed1i \u01b0u cho c\u00e1c thao t\u00e1c ghi t\u1ea7n su\u1ea5t cao c\u00f3 th\u1ec3 ho\u1ea1t \u0111\u1ed9ng kh\u00e1c bi\u1ec7t so v\u1edbi m\u1ed9t l\u01b0\u1ee3c \u0111\u1ed3 \u0111\u01b0\u1ee3c t\u1ed1i \u01b0u cho c\u00e1c truy v\u1ea5n ph\u00e2n t\u00edch ph\u1ee9c t\u1ea1p. M\u1ee5c ti\u00eau l\u00e0 \u0111i\u1ec1u ch\u1ec9nh thi\u1ebft k\u1ebf l\u01b0\u1ee3c \u0111\u1ed3 ph\u00f9 h\u1ee3p v\u1edbi c\u00e1c m\u1eabu truy c\u1eadp c\u1ee5 th\u1ec3 c\u1ee7a \u1ee9ng d\u1ee5ng b\u1ea1n. Th\u01b0\u1eddng xuy\u00ean xem x\u00e9t l\u1ea1i s\u01a1 \u0111\u1ed3 ERD d\u1ef1a tr\u00ean c\u00e1c ch\u1ec9 s\u1ed1 hi\u1ec7u su\u1ea5t truy v\u1ea5n th\u1ef1c t\u1ebf \u0111\u1ec3 ph\u00e1t hi\u1ec7n s\u1ef1 l\u1ec7ch l\u1ea1c s\u1edbm.<\/p>\n<p>B\u1eb1ng c\u00e1ch t\u1eadp trung v\u00e0o t\u00ednh to\u00e0n v\u1eb9n c\u1ea5u tr\u00fac c\u1ee7a m\u00f4 h\u00ecnh d\u1eef li\u1ec7u, b\u1ea1n lo\u1ea1i b\u1ecf nguy\u00ean nh\u00e2n g\u1ed1c r\u1ec5 g\u00e2y ra \u0111\u1ed9 tr\u1ec5. C\u00e1ch ti\u1ebfp c\u1eadn n\u00e0y b\u1ec1n v\u1eefng h\u01a1n so v\u1edbi vi\u1ec7c \u00e1p d\u1ee5ng c\u00e1c b\u1ea3n v\u00e1 \u1edf l\u1edbp \u1ee9ng d\u1ee5ng. M\u1ed9t n\u1ec1n t\u1ea3ng l\u01b0\u1ee3c \u0111\u1ed3 v\u1eefng ch\u1eafc \u0111\u1ea3m b\u1ea3o h\u1ec7 th\u1ed1ng c\u00f3 th\u1ec3 m\u1edf r\u1ed9ng, th\u00edch nghi v\u00e0 ho\u1ea1t \u0111\u1ed9ng \u1ed5n \u0111\u1ecbnh theo th\u1eddi gian.<\/p>\n<p>V\u1eabn ti\u1ebfp t\u1ee5c gi\u00e1m s\u00e1t c\u00e1c k\u1ebf ho\u1ea1ch th\u1ef1c thi truy v\u1ea5n sau khi th\u1ef1c hi\u1ec7n thay \u0111\u1ed5i. Vi\u1ec7c tr\u1ef1c quan h\u00f3a k\u1ebf ho\u1ea1ch th\u1ef1c thi c\u00f3 th\u1ec3 x\u00e1c nh\u1eadn r\u1eb1ng b\u1ed9 t\u1ed1i \u01b0u \u0111ang s\u1eed d\u1ee5ng \u0111\u00fang c\u00e1c ch\u1ec9 m\u1ee5c v\u00e0 r\u00e0ng bu\u1ed9c m\u1edbi. V\u00f2ng ph\u1ea3n h\u1ed3i n\u00e0y ho\u00e0n thi\u1ec7n chu tr\u00ecnh kh\u1eafc ph\u1ee5c s\u1ef1 c\u1ed1, \u0111\u1ea3m b\u1ea3o r\u1eb1ng nh\u1eefng c\u1ea3i ti\u1ebfn l\u00fd thuy\u1ebft trong s\u01a1 \u0111\u1ed3 ERD \u0111\u01b0\u1ee3c chuy\u1ec3n h\u00f3a th\u00e0nh c\u00e1c c\u1ea3i thi\u1ec7n hi\u1ec7u su\u1ea5t th\u1ef1c t\u1ebf trong m\u00f4i tr\u01b0\u1eddng ho\u1ea1t \u0111\u1ed9ng.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Hi\u1ec7u su\u1ea5t c\u01a1 s\u1edf d\u1eef li\u1ec7u th\u01b0\u1eddng v\u00f4 h\u00ecnh cho \u0111\u1ebfn khi tr\u1edf th\u00e0nh \u0111i\u1ec3m ngh\u1ebdn nghi\u00eam tr\u1ecdng. Khi ng\u01b0\u1eddi d\u00f9ng g\u1eb7p \u0111\u1ed9 tr\u1ec5, th\u1eddi gian ch\u1edd v\u01b0\u1ee3t qu\u00e1 gi\u1edbi&hellip;<\/p>\n","protected":false},"author":1,"featured_media":1628,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_yoast_wpseo_title":"Kh\u1eafc ph\u1ee5c s\u1ef1 c\u1ed1 ERD: Ch\u1ea9n \u0111o\u00e1n c\u00e1c truy v\u1ea5n ch\u1eadm th\u00f4ng qua thi\u1ebft k\u1ebf l\u01b0\u1ee3c \u0111\u1ed3 \ud83d\udc22","_yoast_wpseo_metadesc":"H\u1ecdc c\u00e1ch ch\u1ea9n \u0111o\u00e1n c\u00e1c truy v\u1ea5n ch\u1eadm do thi\u1ebft k\u1ebf l\u01b0\u1ee3c \u0111\u1ed3 k\u00e9m. Ph\u00e2n t\u00edch c\u00e1c s\u01a1 \u0111\u1ed3 ERD \u0111\u1ec3 kh\u1eafc ph\u1ee5c c\u00e1c v\u1ea5n \u0111\u1ec1 v\u1ec1 chu\u1ea9n h\u00f3a, ch\u1ec9 m\u1ee5c v\u00e0 m\u1ed1i quan h\u1ec7 nh\u1eb1m \u0111\u1ea1t hi\u1ec7u su\u1ea5t c\u01a1 s\u1edf d\u1eef li\u1ec7u t\u1ed1i \u01b0u.","fifu_image_url":"","fifu_image_alt":"","footnotes":""},"categories":[68],"tags":[89,92],"class_list":["post-1627","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-database-design","tag-academic","tag-erd"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.1.1 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>Kh\u1eafc ph\u1ee5c s\u1ef1 c\u1ed1 ERD: Ch\u1ea9n \u0111o\u00e1n c\u00e1c truy v\u1ea5n ch\u1eadm th\u00f4ng qua thi\u1ebft k\u1ebf l\u01b0\u1ee3c \u0111\u1ed3 \ud83d\udc22<\/title>\n<meta name=\"description\" content=\"H\u1ecdc c\u00e1ch ch\u1ea9n \u0111o\u00e1n c\u00e1c truy v\u1ea5n ch\u1eadm do thi\u1ebft k\u1ebf l\u01b0\u1ee3c \u0111\u1ed3 k\u00e9m. Ph\u00e2n t\u00edch c\u00e1c s\u01a1 \u0111\u1ed3 ERD \u0111\u1ec3 kh\u1eafc ph\u1ee5c c\u00e1c v\u1ea5n \u0111\u1ec1 v\u1ec1 chu\u1ea9n h\u00f3a, ch\u1ec9 m\u1ee5c v\u00e0 m\u1ed1i quan h\u1ec7 nh\u1eb1m \u0111\u1ea1t hi\u1ec7u su\u1ea5t c\u01a1 s\u1edf d\u1eef li\u1ec7u t\u1ed1i \u01b0u.\" \/>\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.viz-note.com\/vi\/erd-troubleshooting-slow-query-schema-design\/\" \/>\n<meta property=\"og:locale\" content=\"vi_VN\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Kh\u1eafc ph\u1ee5c s\u1ef1 c\u1ed1 ERD: Ch\u1ea9n \u0111o\u00e1n c\u00e1c truy v\u1ea5n ch\u1eadm th\u00f4ng qua thi\u1ebft k\u1ebf l\u01b0\u1ee3c \u0111\u1ed3 \ud83d\udc22\" \/>\n<meta property=\"og:description\" content=\"H\u1ecdc c\u00e1ch ch\u1ea9n \u0111o\u00e1n c\u00e1c truy v\u1ea5n ch\u1eadm do thi\u1ebft k\u1ebf l\u01b0\u1ee3c \u0111\u1ed3 k\u00e9m. Ph\u00e2n t\u00edch c\u00e1c s\u01a1 \u0111\u1ed3 ERD \u0111\u1ec3 kh\u1eafc ph\u1ee5c c\u00e1c v\u1ea5n \u0111\u1ec1 v\u1ec1 chu\u1ea9n h\u00f3a, ch\u1ec9 m\u1ee5c v\u00e0 m\u1ed1i quan h\u1ec7 nh\u1eb1m \u0111\u1ea1t hi\u1ec7u su\u1ea5t c\u01a1 s\u1edf d\u1eef li\u1ec7u t\u1ed1i \u01b0u.\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.viz-note.com\/vi\/erd-troubleshooting-slow-query-schema-design\/\" \/>\n<meta property=\"og:site_name\" content=\"Viz Note Vietnamese - AI Insights &amp; Software Industry Updates\" \/>\n<meta property=\"article:published_time\" content=\"2026-04-09T02:30:54+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/www.viz-note.com\/vi\/wp-content\/uploads\/sites\/10\/2026\/04\/erd-troubleshooting-infographic-charcoal-sketch.jpg\" \/>\n\t<meta property=\"og:image:width\" content=\"1664\" \/>\n\t<meta property=\"og:image:height\" content=\"928\" \/>\n\t<meta property=\"og:image:type\" content=\"image\/jpeg\" \/>\n<meta name=\"author\" content=\"vpadmin\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"\u0110\u01b0\u1ee3c vi\u1ebft b\u1edfi\" \/>\n\t<meta name=\"twitter:data1\" content=\"vpadmin\" \/>\n\t<meta name=\"twitter:label2\" content=\"\u01af\u1edbc t\u00ednh th\u1eddi gian \u0111\u1ecdc\" \/>\n\t<meta name=\"twitter:data2\" content=\"24 ph\u00fat\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\/\/www.viz-note.com\/vi\/erd-troubleshooting-slow-query-schema-design\/#article\",\"isPartOf\":{\"@id\":\"https:\/\/www.viz-note.com\/vi\/erd-troubleshooting-slow-query-schema-design\/\"},\"author\":{\"name\":\"vpadmin\",\"@id\":\"https:\/\/www.viz-note.com\/vi\/#\/schema\/person\/d69595112293b803501f7b381be28255\"},\"headline\":\"Kh\u1eafc ph\u1ee5c s\u1ef1 c\u1ed1 s\u01a1 \u0111\u1ed3 quan h\u1ec7 th\u1ef1c th\u1ec3: Ch\u1ea9n \u0111o\u00e1n c\u00e1c truy v\u1ea5n ch\u1eadm do thi\u1ebft k\u1ebf l\u01b0\u1ee3c \u0111\u1ed3 k\u00e9m hi\u1ec7u qu\u1ea3\",\"datePublished\":\"2026-04-09T02:30:54+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\/\/www.viz-note.com\/vi\/erd-troubleshooting-slow-query-schema-design\/\"},\"wordCount\":4903,\"publisher\":{\"@id\":\"https:\/\/www.viz-note.com\/vi\/#organization\"},\"image\":{\"@id\":\"https:\/\/www.viz-note.com\/vi\/erd-troubleshooting-slow-query-schema-design\/#primaryimage\"},\"thumbnailUrl\":\"https:\/\/www.viz-note.com\/vi\/wp-content\/uploads\/sites\/10\/2026\/04\/erd-troubleshooting-infographic-charcoal-sketch.jpg\",\"keywords\":[\"academic\",\"erd\"],\"articleSection\":[\"Database Design\"],\"inLanguage\":\"vi\"},{\"@type\":\"WebPage\",\"@id\":\"https:\/\/www.viz-note.com\/vi\/erd-troubleshooting-slow-query-schema-design\/\",\"url\":\"https:\/\/www.viz-note.com\/vi\/erd-troubleshooting-slow-query-schema-design\/\",\"name\":\"Kh\u1eafc ph\u1ee5c s\u1ef1 c\u1ed1 ERD: Ch\u1ea9n \u0111o\u00e1n c\u00e1c truy v\u1ea5n ch\u1eadm th\u00f4ng qua thi\u1ebft k\u1ebf l\u01b0\u1ee3c \u0111\u1ed3 \ud83d\udc22\",\"isPartOf\":{\"@id\":\"https:\/\/www.viz-note.com\/vi\/#website\"},\"primaryImageOfPage\":{\"@id\":\"https:\/\/www.viz-note.com\/vi\/erd-troubleshooting-slow-query-schema-design\/#primaryimage\"},\"image\":{\"@id\":\"https:\/\/www.viz-note.com\/vi\/erd-troubleshooting-slow-query-schema-design\/#primaryimage\"},\"thumbnailUrl\":\"https:\/\/www.viz-note.com\/vi\/wp-content\/uploads\/sites\/10\/2026\/04\/erd-troubleshooting-infographic-charcoal-sketch.jpg\",\"datePublished\":\"2026-04-09T02:30:54+00:00\",\"description\":\"H\u1ecdc c\u00e1ch ch\u1ea9n \u0111o\u00e1n c\u00e1c truy v\u1ea5n ch\u1eadm do thi\u1ebft k\u1ebf l\u01b0\u1ee3c \u0111\u1ed3 k\u00e9m. Ph\u00e2n t\u00edch c\u00e1c s\u01a1 \u0111\u1ed3 ERD \u0111\u1ec3 kh\u1eafc ph\u1ee5c c\u00e1c v\u1ea5n \u0111\u1ec1 v\u1ec1 chu\u1ea9n h\u00f3a, ch\u1ec9 m\u1ee5c v\u00e0 m\u1ed1i quan h\u1ec7 nh\u1eb1m \u0111\u1ea1t hi\u1ec7u su\u1ea5t c\u01a1 s\u1edf d\u1eef li\u1ec7u t\u1ed1i \u01b0u.\",\"breadcrumb\":{\"@id\":\"https:\/\/www.viz-note.com\/vi\/erd-troubleshooting-slow-query-schema-design\/#breadcrumb\"},\"inLanguage\":\"vi\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\/\/www.viz-note.com\/vi\/erd-troubleshooting-slow-query-schema-design\/\"]}]},{\"@type\":\"ImageObject\",\"inLanguage\":\"vi\",\"@id\":\"https:\/\/www.viz-note.com\/vi\/erd-troubleshooting-slow-query-schema-design\/#primaryimage\",\"url\":\"https:\/\/www.viz-note.com\/vi\/wp-content\/uploads\/sites\/10\/2026\/04\/erd-troubleshooting-infographic-charcoal-sketch.jpg\",\"contentUrl\":\"https:\/\/www.viz-note.com\/vi\/wp-content\/uploads\/sites\/10\/2026\/04\/erd-troubleshooting-infographic-charcoal-sketch.jpg\",\"width\":1664,\"height\":928},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\/\/www.viz-note.com\/vi\/erd-troubleshooting-slow-query-schema-design\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\/\/www.viz-note.com\/vi\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Kh\u1eafc ph\u1ee5c s\u1ef1 c\u1ed1 s\u01a1 \u0111\u1ed3 quan h\u1ec7 th\u1ef1c th\u1ec3: Ch\u1ea9n \u0111o\u00e1n c\u00e1c truy v\u1ea5n ch\u1eadm do thi\u1ebft k\u1ebf l\u01b0\u1ee3c \u0111\u1ed3 k\u00e9m hi\u1ec7u qu\u1ea3\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\/\/www.viz-note.com\/vi\/#website\",\"url\":\"https:\/\/www.viz-note.com\/vi\/\",\"name\":\"Viz Note Vietnamese - AI Insights &amp; Software Industry Updates\",\"description\":\"\",\"publisher\":{\"@id\":\"https:\/\/www.viz-note.com\/vi\/#organization\"},\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\/\/www.viz-note.com\/vi\/?s={search_term_string}\"},\"query-input\":{\"@type\":\"PropertyValueSpecification\",\"valueRequired\":true,\"valueName\":\"search_term_string\"}}],\"inLanguage\":\"vi\"},{\"@type\":\"Organization\",\"@id\":\"https:\/\/www.viz-note.com\/vi\/#organization\",\"name\":\"Viz Note Vietnamese - AI Insights &amp; Software Industry Updates\",\"url\":\"https:\/\/www.viz-note.com\/vi\/\",\"logo\":{\"@type\":\"ImageObject\",\"inLanguage\":\"vi\",\"@id\":\"https:\/\/www.viz-note.com\/vi\/#\/schema\/logo\/image\/\",\"url\":\"https:\/\/www.viz-note.com\/vi\/wp-content\/uploads\/sites\/10\/2025\/03\/cropped-viz-note-logo.png\",\"contentUrl\":\"https:\/\/www.viz-note.com\/vi\/wp-content\/uploads\/sites\/10\/2025\/03\/cropped-viz-note-logo.png\",\"width\":512,\"height\":512,\"caption\":\"Viz Note Vietnamese - AI Insights &amp; Software Industry Updates\"},\"image\":{\"@id\":\"https:\/\/www.viz-note.com\/vi\/#\/schema\/logo\/image\/\"}},{\"@type\":\"Person\",\"@id\":\"https:\/\/www.viz-note.com\/vi\/#\/schema\/person\/d69595112293b803501f7b381be28255\",\"name\":\"vpadmin\",\"image\":{\"@type\":\"ImageObject\",\"inLanguage\":\"vi\",\"@id\":\"https:\/\/www.viz-note.com\/vi\/#\/schema\/person\/image\/\",\"url\":\"https:\/\/secure.gravatar.com\/avatar\/56e0eb902506d9cea7c7e209205383146b8e81c0ef2eff693d9d5e0276b3d7e3?s=96&d=mm&r=g\",\"contentUrl\":\"https:\/\/secure.gravatar.com\/avatar\/56e0eb902506d9cea7c7e209205383146b8e81c0ef2eff693d9d5e0276b3d7e3?s=96&d=mm&r=g\",\"caption\":\"vpadmin\"},\"sameAs\":[\"https:\/\/www.viz-note.com\"],\"url\":\"https:\/\/www.viz-note.com\/vi\/author\/vpadmin\/\"}]}<\/script>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"Kh\u1eafc ph\u1ee5c s\u1ef1 c\u1ed1 ERD: Ch\u1ea9n \u0111o\u00e1n c\u00e1c truy v\u1ea5n ch\u1eadm th\u00f4ng qua thi\u1ebft k\u1ebf l\u01b0\u1ee3c \u0111\u1ed3 \ud83d\udc22","description":"H\u1ecdc c\u00e1ch ch\u1ea9n \u0111o\u00e1n c\u00e1c truy v\u1ea5n ch\u1eadm do thi\u1ebft k\u1ebf l\u01b0\u1ee3c \u0111\u1ed3 k\u00e9m. Ph\u00e2n t\u00edch c\u00e1c s\u01a1 \u0111\u1ed3 ERD \u0111\u1ec3 kh\u1eafc ph\u1ee5c c\u00e1c v\u1ea5n \u0111\u1ec1 v\u1ec1 chu\u1ea9n h\u00f3a, ch\u1ec9 m\u1ee5c v\u00e0 m\u1ed1i quan h\u1ec7 nh\u1eb1m \u0111\u1ea1t hi\u1ec7u su\u1ea5t c\u01a1 s\u1edf d\u1eef li\u1ec7u t\u1ed1i \u01b0u.","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/www.viz-note.com\/vi\/erd-troubleshooting-slow-query-schema-design\/","og_locale":"vi_VN","og_type":"article","og_title":"Kh\u1eafc ph\u1ee5c s\u1ef1 c\u1ed1 ERD: Ch\u1ea9n \u0111o\u00e1n c\u00e1c truy v\u1ea5n ch\u1eadm th\u00f4ng qua thi\u1ebft k\u1ebf l\u01b0\u1ee3c \u0111\u1ed3 \ud83d\udc22","og_description":"H\u1ecdc c\u00e1ch ch\u1ea9n \u0111o\u00e1n c\u00e1c truy v\u1ea5n ch\u1eadm do thi\u1ebft k\u1ebf l\u01b0\u1ee3c \u0111\u1ed3 k\u00e9m. Ph\u00e2n t\u00edch c\u00e1c s\u01a1 \u0111\u1ed3 ERD \u0111\u1ec3 kh\u1eafc ph\u1ee5c c\u00e1c v\u1ea5n \u0111\u1ec1 v\u1ec1 chu\u1ea9n h\u00f3a, ch\u1ec9 m\u1ee5c v\u00e0 m\u1ed1i quan h\u1ec7 nh\u1eb1m \u0111\u1ea1t hi\u1ec7u su\u1ea5t c\u01a1 s\u1edf d\u1eef li\u1ec7u t\u1ed1i \u01b0u.","og_url":"https:\/\/www.viz-note.com\/vi\/erd-troubleshooting-slow-query-schema-design\/","og_site_name":"Viz Note Vietnamese - AI Insights &amp; Software Industry Updates","article_published_time":"2026-04-09T02:30:54+00:00","og_image":[{"width":1664,"height":928,"url":"https:\/\/www.viz-note.com\/vi\/wp-content\/uploads\/sites\/10\/2026\/04\/erd-troubleshooting-infographic-charcoal-sketch.jpg","type":"image\/jpeg"}],"author":"vpadmin","twitter_card":"summary_large_image","twitter_misc":{"\u0110\u01b0\u1ee3c vi\u1ebft b\u1edfi":"vpadmin","\u01af\u1edbc t\u00ednh th\u1eddi gian \u0111\u1ecdc":"24 ph\u00fat"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"Article","@id":"https:\/\/www.viz-note.com\/vi\/erd-troubleshooting-slow-query-schema-design\/#article","isPartOf":{"@id":"https:\/\/www.viz-note.com\/vi\/erd-troubleshooting-slow-query-schema-design\/"},"author":{"name":"vpadmin","@id":"https:\/\/www.viz-note.com\/vi\/#\/schema\/person\/d69595112293b803501f7b381be28255"},"headline":"Kh\u1eafc ph\u1ee5c s\u1ef1 c\u1ed1 s\u01a1 \u0111\u1ed3 quan h\u1ec7 th\u1ef1c th\u1ec3: Ch\u1ea9n \u0111o\u00e1n c\u00e1c truy v\u1ea5n ch\u1eadm do thi\u1ebft k\u1ebf l\u01b0\u1ee3c \u0111\u1ed3 k\u00e9m hi\u1ec7u qu\u1ea3","datePublished":"2026-04-09T02:30:54+00:00","mainEntityOfPage":{"@id":"https:\/\/www.viz-note.com\/vi\/erd-troubleshooting-slow-query-schema-design\/"},"wordCount":4903,"publisher":{"@id":"https:\/\/www.viz-note.com\/vi\/#organization"},"image":{"@id":"https:\/\/www.viz-note.com\/vi\/erd-troubleshooting-slow-query-schema-design\/#primaryimage"},"thumbnailUrl":"https:\/\/www.viz-note.com\/vi\/wp-content\/uploads\/sites\/10\/2026\/04\/erd-troubleshooting-infographic-charcoal-sketch.jpg","keywords":["academic","erd"],"articleSection":["Database Design"],"inLanguage":"vi"},{"@type":"WebPage","@id":"https:\/\/www.viz-note.com\/vi\/erd-troubleshooting-slow-query-schema-design\/","url":"https:\/\/www.viz-note.com\/vi\/erd-troubleshooting-slow-query-schema-design\/","name":"Kh\u1eafc ph\u1ee5c s\u1ef1 c\u1ed1 ERD: Ch\u1ea9n \u0111o\u00e1n c\u00e1c truy v\u1ea5n ch\u1eadm th\u00f4ng qua thi\u1ebft k\u1ebf l\u01b0\u1ee3c \u0111\u1ed3 \ud83d\udc22","isPartOf":{"@id":"https:\/\/www.viz-note.com\/vi\/#website"},"primaryImageOfPage":{"@id":"https:\/\/www.viz-note.com\/vi\/erd-troubleshooting-slow-query-schema-design\/#primaryimage"},"image":{"@id":"https:\/\/www.viz-note.com\/vi\/erd-troubleshooting-slow-query-schema-design\/#primaryimage"},"thumbnailUrl":"https:\/\/www.viz-note.com\/vi\/wp-content\/uploads\/sites\/10\/2026\/04\/erd-troubleshooting-infographic-charcoal-sketch.jpg","datePublished":"2026-04-09T02:30:54+00:00","description":"H\u1ecdc c\u00e1ch ch\u1ea9n \u0111o\u00e1n c\u00e1c truy v\u1ea5n ch\u1eadm do thi\u1ebft k\u1ebf l\u01b0\u1ee3c \u0111\u1ed3 k\u00e9m. Ph\u00e2n t\u00edch c\u00e1c s\u01a1 \u0111\u1ed3 ERD \u0111\u1ec3 kh\u1eafc ph\u1ee5c c\u00e1c v\u1ea5n \u0111\u1ec1 v\u1ec1 chu\u1ea9n h\u00f3a, ch\u1ec9 m\u1ee5c v\u00e0 m\u1ed1i quan h\u1ec7 nh\u1eb1m \u0111\u1ea1t hi\u1ec7u su\u1ea5t c\u01a1 s\u1edf d\u1eef li\u1ec7u t\u1ed1i \u01b0u.","breadcrumb":{"@id":"https:\/\/www.viz-note.com\/vi\/erd-troubleshooting-slow-query-schema-design\/#breadcrumb"},"inLanguage":"vi","potentialAction":[{"@type":"ReadAction","target":["https:\/\/www.viz-note.com\/vi\/erd-troubleshooting-slow-query-schema-design\/"]}]},{"@type":"ImageObject","inLanguage":"vi","@id":"https:\/\/www.viz-note.com\/vi\/erd-troubleshooting-slow-query-schema-design\/#primaryimage","url":"https:\/\/www.viz-note.com\/vi\/wp-content\/uploads\/sites\/10\/2026\/04\/erd-troubleshooting-infographic-charcoal-sketch.jpg","contentUrl":"https:\/\/www.viz-note.com\/vi\/wp-content\/uploads\/sites\/10\/2026\/04\/erd-troubleshooting-infographic-charcoal-sketch.jpg","width":1664,"height":928},{"@type":"BreadcrumbList","@id":"https:\/\/www.viz-note.com\/vi\/erd-troubleshooting-slow-query-schema-design\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/www.viz-note.com\/vi\/"},{"@type":"ListItem","position":2,"name":"Kh\u1eafc ph\u1ee5c s\u1ef1 c\u1ed1 s\u01a1 \u0111\u1ed3 quan h\u1ec7 th\u1ef1c th\u1ec3: Ch\u1ea9n \u0111o\u00e1n c\u00e1c truy v\u1ea5n ch\u1eadm do thi\u1ebft k\u1ebf l\u01b0\u1ee3c \u0111\u1ed3 k\u00e9m hi\u1ec7u qu\u1ea3"}]},{"@type":"WebSite","@id":"https:\/\/www.viz-note.com\/vi\/#website","url":"https:\/\/www.viz-note.com\/vi\/","name":"Viz Note Vietnamese - AI Insights &amp; Software Industry Updates","description":"","publisher":{"@id":"https:\/\/www.viz-note.com\/vi\/#organization"},"potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/www.viz-note.com\/vi\/?s={search_term_string}"},"query-input":{"@type":"PropertyValueSpecification","valueRequired":true,"valueName":"search_term_string"}}],"inLanguage":"vi"},{"@type":"Organization","@id":"https:\/\/www.viz-note.com\/vi\/#organization","name":"Viz Note Vietnamese - AI Insights &amp; Software Industry Updates","url":"https:\/\/www.viz-note.com\/vi\/","logo":{"@type":"ImageObject","inLanguage":"vi","@id":"https:\/\/www.viz-note.com\/vi\/#\/schema\/logo\/image\/","url":"https:\/\/www.viz-note.com\/vi\/wp-content\/uploads\/sites\/10\/2025\/03\/cropped-viz-note-logo.png","contentUrl":"https:\/\/www.viz-note.com\/vi\/wp-content\/uploads\/sites\/10\/2025\/03\/cropped-viz-note-logo.png","width":512,"height":512,"caption":"Viz Note Vietnamese - AI Insights &amp; Software Industry Updates"},"image":{"@id":"https:\/\/www.viz-note.com\/vi\/#\/schema\/logo\/image\/"}},{"@type":"Person","@id":"https:\/\/www.viz-note.com\/vi\/#\/schema\/person\/d69595112293b803501f7b381be28255","name":"vpadmin","image":{"@type":"ImageObject","inLanguage":"vi","@id":"https:\/\/www.viz-note.com\/vi\/#\/schema\/person\/image\/","url":"https:\/\/secure.gravatar.com\/avatar\/56e0eb902506d9cea7c7e209205383146b8e81c0ef2eff693d9d5e0276b3d7e3?s=96&d=mm&r=g","contentUrl":"https:\/\/secure.gravatar.com\/avatar\/56e0eb902506d9cea7c7e209205383146b8e81c0ef2eff693d9d5e0276b3d7e3?s=96&d=mm&r=g","caption":"vpadmin"},"sameAs":["https:\/\/www.viz-note.com"],"url":"https:\/\/www.viz-note.com\/vi\/author\/vpadmin\/"}]}},"_links":{"self":[{"href":"https:\/\/www.viz-note.com\/vi\/wp-json\/wp\/v2\/posts\/1627","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.viz-note.com\/vi\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.viz-note.com\/vi\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.viz-note.com\/vi\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.viz-note.com\/vi\/wp-json\/wp\/v2\/comments?post=1627"}],"version-history":[{"count":0,"href":"https:\/\/www.viz-note.com\/vi\/wp-json\/wp\/v2\/posts\/1627\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.viz-note.com\/vi\/wp-json\/wp\/v2\/media\/1628"}],"wp:attachment":[{"href":"https:\/\/www.viz-note.com\/vi\/wp-json\/wp\/v2\/media?parent=1627"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.viz-note.com\/vi\/wp-json\/wp\/v2\/categories?post=1627"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.viz-note.com\/vi\/wp-json\/wp\/v2\/tags?post=1627"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}