{"id":30664,"date":"2023-09-18T09:57:34","date_gmt":"2023-09-18T02:57:34","guid":{"rendered":"https:\/\/ungdung.hotronghiencuu.com\/open\/truy-van-co-so-du-lieu-la-gi"},"modified":"2023-09-18T09:57:34","modified_gmt":"2023-09-18T02:57:34","slug":"truy-van-co-so-du-lieu-la-gi","status":"publish","type":"post","link":"https:\/\/ungdung.hotronghiencuu.com\/open\/truy-van-co-so-du-lieu-la-gi","title":{"rendered":"T\u00ecm hi\u1ec3u v\u1ec1 truy v\u1ea5n c\u01a1 s\u1edf d\u1eef li\u1ec7u v\u00e0 c\u00e1ch qu\u1ea3n l\u00fd d\u1eef li\u1ec7u hi\u1ec7u qu\u1ea3"},"content":{"rendered":"<p>Truy v\u1ea5n c\u01a1 s\u1edf d\u1eef li\u1ec7u l\u00e0 qu\u00e1 tr\u00ecnh t\u00ecm ki\u1ebfm th\u00f4ng tin t\u1eeb m\u1ed9t h\u1ec7 th\u1ed1ng l\u01b0u tr\u1eef d\u1eef li\u1ec7u. B\u1eb1ng c\u00e1ch s\u1eed d\u1ee5ng ng\u00f4n ng\u1eef truy v\u1ea5n, ch\u00fang ta c\u00f3 th\u1ec3 tr\u00edch xu\u1ea5t, c\u1eadp nh\u1eadt v\u00e0 x\u00f3a d\u1eef li\u1ec7u m\u1ed9t c\u00e1ch nhanh ch\u00f3ng v\u00e0 hi\u1ec7u qu\u1ea3. Truy v\u1ea5n c\u01a1 s\u1edf d\u1eef li\u1ec7u \u0111\u00f3ng vai tr\u00f2 quan tr\u1ecdng trong vi\u1ec7c ph\u00e2n t\u00edch v\u00e0 qu\u1ea3n l\u00fd th\u00f4ng tin trong c\u00e1c h\u1ec7 th\u1ed1ng c\u00f4ng nghi\u1ec7p v\u00e0 kinh doanh.<\/p>\n<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_40 counter-hierarchy ez-toc-counter ez-toc-grey ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title\">Table of Contents<\/p>\n<span class=\"ez-toc-title-toggle\"><a href=\"#\" class=\"ez-toc-pull-right ez-toc-btn ez-toc-btn-xs ez-toc-btn-default ez-toc-toggle\" area-label=\"ez-toc-toggle-icon-1\"><label for=\"item-6ad16e93e2ada\" aria-label=\"Table of Content\"><span style=\"display: flex;align-items: center;width: 35px;height: 30px;justify-content: center;direction:ltr;\"><svg style=\"fill: #999;color:#999\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #999;color:#999\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/label><input  type=\"checkbox\" id=\"item-6ad16e93e2ada\"><\/a><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/ungdung.hotronghiencuu.com\/open\/truy-van-co-so-du-lieu-la-gi\/#1_Truy_van_co_so_du_lieu\" title=\"1. Truy v\u1ea5n c\u01a1 s\u1edf d\u1eef li\u1ec7u\">1. Truy v\u1ea5n c\u01a1 s\u1edf d\u1eef li\u1ec7u<\/a><ul class='ez-toc-list-level-3'><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/ungdung.hotronghiencuu.com\/open\/truy-van-co-so-du-lieu-la-gi\/#Khai_niem\" title=\"Kh\u00e1i ni\u1ec7m:\">Kh\u00e1i ni\u1ec7m:<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/ungdung.hotronghiencuu.com\/open\/truy-van-co-so-du-lieu-la-gi\/#Cac_loai_truy_van\" title=\"C\u00e1c lo\u1ea1i truy v\u1ea5n:\">C\u00e1c lo\u1ea1i truy v\u1ea5n:<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/ungdung.hotronghiencuu.com\/open\/truy-van-co-so-du-lieu-la-gi\/#2_He_quan_tri_co_so_du_lieu\" title=\"2. H\u1ec7 qu\u1ea3n tr\u1ecb c\u01a1 s\u1edf d\u1eef li\u1ec7u\">2. H\u1ec7 qu\u1ea3n tr\u1ecb c\u01a1 s\u1edf d\u1eef li\u1ec7u<\/a><ul class='ez-toc-list-level-3'><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/ungdung.hotronghiencuu.com\/open\/truy-van-co-so-du-lieu-la-gi\/#Khai_niem-2\" title=\"Kh\u00e1i ni\u1ec7m:\">Kh\u00e1i ni\u1ec7m:<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/ungdung.hotronghiencuu.com\/open\/truy-van-co-so-du-lieu-la-gi\/#Cac_chuc_nang_cua_DBMS\" title=\"C\u00e1c ch\u1ee9c n\u0103ng c\u1ee7a DBMS:\">C\u00e1c ch\u1ee9c n\u0103ng c\u1ee7a DBMS:<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/ungdung.hotronghiencuu.com\/open\/truy-van-co-so-du-lieu-la-gi\/#3_Ngon_ngu_truy_van_co_so_du_lieu\" title=\"3. Ng\u00f4n ng\u1eef truy v\u1ea5n c\u01a1 s\u1edf d\u1eef li\u1ec7u\">3. Ng\u00f4n ng\u1eef truy v\u1ea5n c\u01a1 s\u1edf d\u1eef li\u1ec7u<\/a><ul class='ez-toc-list-level-3'><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"https:\/\/ungdung.hotronghiencuu.com\/open\/truy-van-co-so-du-lieu-la-gi\/#31_SQL_Structured_Query_Language\" title=\"3.1 SQL (Structured Query Language)\">3.1 SQL (Structured Query Language)<\/a><ul class='ez-toc-list-level-4'><li class='ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-9\" href=\"https:\/\/ungdung.hotronghiencuu.com\/open\/truy-van-co-so-du-lieu-la-gi\/#Uu_diem_cua_SQL\" title=\"\u01afu \u0111i\u1ec3m c\u1ee7a SQL:\">\u01afu \u0111i\u1ec3m c\u1ee7a SQL:<\/a><\/li><\/ul><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-10\" href=\"https:\/\/ungdung.hotronghiencuu.com\/open\/truy-van-co-so-du-lieu-la-gi\/#4_Co_so_du_lieu_quan_he\" title=\"4. C\u01a1 s\u1edf d\u1eef li\u1ec7u quan h\u1ec7\">4. C\u01a1 s\u1edf d\u1eef li\u1ec7u quan h\u1ec7<\/a><ul class='ez-toc-list-level-3'><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-11\" href=\"https:\/\/ungdung.hotronghiencuu.com\/open\/truy-van-co-so-du-lieu-la-gi\/#41_Mo_hinh_quan_he\" title=\"4.1 M\u00f4 h\u00ecnh quan h\u1ec7\">4.1 M\u00f4 h\u00ecnh quan h\u1ec7<\/a><ul class='ez-toc-list-level-4'><li class='ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-12\" href=\"https:\/\/ungdung.hotronghiencuu.com\/open\/truy-van-co-so-du-lieu-la-gi\/#Uu_diem_cua_co_so_du_lieu_quan_he\" title=\"\u01afu \u0111i\u1ec3m c\u1ee7a c\u01a1 s\u1edf d\u1eef li\u1ec7u quan h\u1ec7:\">\u01afu \u0111i\u1ec3m c\u1ee7a c\u01a1 s\u1edf d\u1eef li\u1ec7u quan h\u1ec7:<\/a><\/li><\/ul><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-13\" href=\"https:\/\/ungdung.hotronghiencuu.com\/open\/truy-van-co-so-du-lieu-la-gi\/#5_Bao_mat_co_so_du_lieu\" title=\"5. B\u1ea3o m\u1eadt c\u01a1 s\u1edf d\u1eef li\u1ec7u\">5. B\u1ea3o m\u1eadt c\u01a1 s\u1edf d\u1eef li\u1ec7u<\/a><ul class='ez-toc-list-level-3'><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-14\" href=\"https:\/\/ungdung.hotronghiencuu.com\/open\/truy-van-co-so-du-lieu-la-gi\/#51_Xac_thuc_nguoi_dung\" title=\"5.1 X\u00e1c th\u1ef1c ng\u01b0\u1eddi d\u00f9ng\">5.1 X\u00e1c th\u1ef1c ng\u01b0\u1eddi d\u00f9ng<\/a><ul class='ez-toc-list-level-4'><li class='ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-15\" href=\"https:\/\/ungdung.hotronghiencuu.com\/open\/truy-van-co-so-du-lieu-la-gi\/#Cac_bien_phap_bao_mat_khac\" title=\"C\u00e1c bi\u1ec7n ph\u00e1p b\u1ea3o m\u1eadt kh\u00e1c:\">C\u00e1c bi\u1ec7n ph\u00e1p b\u1ea3o m\u1eadt kh\u00e1c:<\/a><\/li><\/ul><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-16\" href=\"https:\/\/ungdung.hotronghiencuu.com\/open\/truy-van-co-so-du-lieu-la-gi\/#6_Toi_uu_hoa_truy_van\" title=\"6. T\u1ed1i \u01b0u h\u00f3a truy v\u1ea5n\">6. T\u1ed1i \u01b0u h\u00f3a truy v\u1ea5n<\/a><ul class='ez-toc-list-level-3'><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-17\" href=\"https:\/\/ungdung.hotronghiencuu.com\/open\/truy-van-co-so-du-lieu-la-gi\/#61_Chinh_sua_cau_truy_van\" title=\"6.1 Ch\u1ec9nh s\u1eeda c\u00e2u truy v\u1ea5n\">6.1 Ch\u1ec9nh s\u1eeda c\u00e2u truy v\u1ea5n<\/a><ul class='ez-toc-list-level-4'><li class='ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-18\" href=\"https:\/\/ungdung.hotronghiencuu.com\/open\/truy-van-co-so-du-lieu-la-gi\/#Cac_phuong_phap_toi_uu_hoa_khac\" title=\"C\u00e1c ph\u01b0\u01a1ng ph\u00e1p t\u1ed1i \u01b0u h\u00f3a kh\u00e1c:\">C\u00e1c ph\u01b0\u01a1ng ph\u00e1p t\u1ed1i \u01b0u h\u00f3a kh\u00e1c:<\/a><\/li><\/ul><\/li><\/ul><\/li><\/ul><\/nav><\/div>\n<h2><span class=\"ez-toc-section\" id=\"1_Truy_van_co_so_du_lieu\"><\/span>1. Truy v\u1ea5n c\u01a1 s\u1edf d\u1eef li\u1ec7u<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p><img decoding=\"async\" alt=\"1. Truy v\u1ea5n c\u01a1 s\u1edf d\u1eef li\u1ec7u\" src=\"https:\/\/ungdung.hotronghiencuu.com\/open\/wp-content\/uploads\/2023\/09\/tim_hieu_ve_truy_van_co_so_du_lieu_va_cach_quan_ly_du_lieu_hieu_qua.jpeg\" style=\"text-align: center; clear: both; display: block; margin: 0 auto;\" title=\"1. Truy v\u1ea5n c\u01a1 s\u1edf d\u1eef li\u1ec7u\"\/><\/p>\n<h3><span class=\"ez-toc-section\" id=\"Khai_niem\"><\/span>Kh\u00e1i ni\u1ec7m:<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Truy v\u1ea5n c\u01a1 s\u1edf d\u1eef li\u1ec7u l\u00e0 qu\u00e1 tr\u00ecnh l\u1ea5y ra th\u00f4ng tin t\u1eeb c\u01a1 s\u1edf d\u1eef li\u1ec7u theo y\u00eau c\u1ea7u c\u1ee7a ng\u01b0\u1eddi d\u00f9ng. Truy v\u1ea5n c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c th\u1ef1c hi\u1ec7n \u0111\u1ec3 t\u00ecm ki\u1ebfm, l\u1ecdc, s\u1eafp x\u1ebfp ho\u1eb7c t\u00ednh to\u00e1n c\u00e1c th\u00f4ng tin t\u1eeb c\u01a1 s\u1edf d\u1eef li\u1ec7u.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Cac_loai_truy_van\"><\/span>C\u00e1c lo\u1ea1i truy v\u1ea5n:<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<ul>\n<li>Truy v\u1ea5n \u0111\u01a1n gi\u1ea3n: \u0110\u00e2y l\u00e0 lo\u1ea1i truy v\u1ea5n \u0111\u01a1n gi\u1ea3n nh\u1ea5t, ch\u1ec9 y\u00eau c\u1ea7u l\u1ea5y ra c\u00e1c b\u1ea3n ghi t\u1eeb m\u1ed9t b\u1ea3ng trong c\u01a1 s\u1edf d\u1eef li\u1ec7u.<\/li>\n<li>Truy v\u1ea5n gh\u00e9p n\u1ed1i: Lo\u1ea1i truy v\u1ea5n n\u00e0y k\u1ebft h\u1ee3p th\u00f4ng tin t\u1eeb nhi\u1ec1u b\u1ea3ng trong c\u01a1 s\u1edf d\u1eef li\u1ec7u \u0111\u1ec3 t\u1ea1o ra k\u1ebft qu\u1ea3 cu\u1ed1i c\u00f9ng.<\/li>\n<li>Truy v\u1ea5n t\u1ed5 h\u1ee3p: \u0110\u00e2y l\u00e0 lo\u1ea1i truy v\u1ea5n ph\u1ee9c t\u1ea1p, trong \u0111\u00f3 ng\u01b0\u1eddi d\u00f9ng c\u00f3 th\u1ec3 k\u1ebft h\u1ee3p nhi\u1ec1u \u0111i\u1ec1u ki\u1ec7n v\u00e0 to\u00e1n t\u1eed logic \u0111\u1ec3 l\u1ecdc v\u00e0 x\u1eed l\u00fd th\u00f4ng tin t\u1eeb c\u01a1 s\u1edf d\u1eef li\u1ec7u.<\/li>\n<\/ul>\n<h2><span class=\"ez-toc-section\" id=\"2_He_quan_tri_co_so_du_lieu\"><\/span>2. H\u1ec7 qu\u1ea3n tr\u1ecb c\u01a1 s\u1edf d\u1eef li\u1ec7u<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<h3><span class=\"ez-toc-section\" id=\"Khai_niem-2\"><\/span>Kh\u00e1i ni\u1ec7m:<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>H\u1ec7 qu\u1ea3n tr\u1ecb c\u01a1 s\u1edf d\u1eef li\u1ec7u (DBMS) l\u00e0 m\u1ed9t ph\u1ea7n m\u1ec1m ho\u1eb7c h\u1ec7 th\u1ed1ng \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng \u0111\u1ec3 qu\u1ea3n l\u00fd v\u00e0 \u0111i\u1ec1u khi\u1ec3n c\u00e1c c\u01a1 s\u1edf d\u1eef li\u1ec7u. DBMS gi\u00fap ng\u01b0\u1eddi d\u00f9ng t\u1ea1o, l\u01b0u tr\u1eef, truy v\u1ea5n v\u00e0 c\u1eadp nh\u1eadt th\u00f4ng tin trong c\u01a1 s\u1edf d\u1eef li\u1ec7u.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Cac_chuc_nang_cua_DBMS\"><\/span>C\u00e1c ch\u1ee9c n\u0103ng c\u1ee7a DBMS:<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<ul>\n<li>T\u1ea1o v\u00e0 x\u00f3a c\u01a1 s\u1edf d\u1eef li\u1ec7u: DBMS cho ph\u00e9p ng\u01b0\u1eddi d\u00f9ng t\u1ea1o m\u1edbi ho\u1eb7c x\u00f3a b\u1ecf c\u00e1c c\u01a1 s\u1edf d\u1eef li\u1ec7u theo y\u00eau c\u1ea7u.<\/li>\n<li>Qu\u1ea3n l\u00fd b\u1ea3ng v\u00e0 quan h\u1ec7: DBMS gi\u00fap ng\u01b0\u1eddi d\u00f9ng t\u1ea1o, ch\u1ec9nh s\u1eeda v\u00e0 x\u00f3a b\u1ecf c\u00e1c b\u1ea3ng v\u00e0 quan h\u1ec7 trong c\u01a1 s\u1edf d\u1eef li\u1ec7u.<\/li>\n<li>Truy v\u1ea5n v\u00e0 x\u1eed l\u00fd th\u00f4ng tin: DBMS cho ph\u00e9p ng\u01b0\u1eddi d\u00f9ng th\u1ef1c hi\u1ec7n c\u00e1c truy v\u1ea5n \u0111\u1ec3 l\u1ea5y ra th\u00f4ng tin t\u1eeb c\u01a1 s\u1edf d\u1eef li\u1ec7u v\u00e0 x\u1eed l\u00fd n\u00f3 theo y\u00eau c\u1ea7u.<\/li>\n<li>B\u1ea3o m\u1eadt v\u00e0 ph\u00e2n quy\u1ec1n: DBMS \u0111\u1ea3m b\u1ea3o an to\u00e0n cho c\u01a1 s\u1edf d\u1eef li\u1ec7u b\u1eb1ng c\u00e1ch \u00e1p d\u1ee5ng c\u00e1c bi\u1ec7n ph\u00e1p b\u1ea3o m\u1eadt nh\u01b0 m\u00e3 h\u00f3a, ki\u1ec3m tra danh t\u00ednh v\u00e0 ph\u00e2n quy\u1ec1n truy c\u1eadp.<\/li>\n<\/ul>\n<h2><span class=\"ez-toc-section\" id=\"3_Ngon_ngu_truy_van_co_so_du_lieu\"><\/span>3. Ng\u00f4n ng\u1eef truy v\u1ea5n c\u01a1 s\u1edf d\u1eef li\u1ec7u<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<h3><span class=\"ez-toc-section\" id=\"31_SQL_Structured_Query_Language\"><\/span>3.1 SQL (Structured Query Language)<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>SQL l\u00e0 m\u1ed9t ng\u00f4n ng\u1eef truy v\u1ea5n \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng \u0111\u1ec3 t\u01b0\u01a1ng t\u00e1c v\u1edbi c\u01a1 s\u1edf d\u1eef li\u1ec7u quan h\u1ec7. N\u00f3 cho ph\u00e9p ng\u01b0\u1eddi d\u00f9ng th\u1ef1c hi\u1ec7n c\u00e1c thao t\u00e1c nh\u01b0 truy v\u1ea5n, ch\u00e8n, c\u1eadp nh\u1eadt v\u00e0 x\u00f3a d\u1eef li\u1ec7u t\u1eeb c\u01a1 s\u1edf d\u1eef li\u1ec7u. SQL c\u00f3 kh\u1ea3 n\u0103ng linh ho\u1ea1t v\u00e0 m\u1ea1nh m\u1ebd, cho ph\u00e9p ng\u01b0\u1eddi d\u00f9ng truy xu\u1ea5t v\u00e0 x\u1eed l\u00fd d\u1eef li\u1ec7u theo nhi\u1ec1u c\u00e1ch kh\u00e1c nhau.<\/p>\n<h4><span class=\"ez-toc-section\" id=\"Uu_diem_cua_SQL\"><\/span>\u01afu \u0111i\u1ec3m c\u1ee7a SQL:<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<ul>\n<li>D\u1ec5 h\u1ecdc v\u00e0 s\u1eed d\u1ee5ng: SQL c\u00f3 c\u00fa ph\u00e1p \u0111\u01a1n gi\u1ea3n v\u00e0 r\u00f5 r\u00e0ng, gi\u00fap ng\u01b0\u1eddi d\u00f9ng nhanh ch\u00f3ng l\u00e0m quen v\u00e0 s\u1eed d\u1ee5ng.<\/li>\n<li>T\u00edch h\u1ee3p: SQL \u0111\u01b0\u1ee3c h\u1ed7 tr\u1ee3 b\u1edfi h\u1ea7u h\u1ebft c\u00e1c h\u1ec7 qu\u1ea3n tr\u1ecb c\u01a1 s\u1edf d\u1eef li\u1ec7u quan h\u1ec7 ph\u1ed5 bi\u1ebfn nh\u01b0 MySQL, Oracle, SQL Server.<\/li>\n<li>M\u1ea1nh m\u1ebd: SQL cho ph\u00e9p th\u1ef1c hi\u1ec7n c\u00e1c thao t\u00e1c ph\u1ee9c t\u1ea1p nh\u01b0 k\u1ebft h\u1ee3p b\u1ea3ng, t\u1ed5 ch\u1ee9c l\u1ea1i d\u1eef li\u1ec7u v\u00e0 t\u00ednh to\u00e1n trong c\u00e2u truy v\u1ea5n.<\/li>\n<\/ul>\n<h2><span class=\"ez-toc-section\" id=\"4_Co_so_du_lieu_quan_he\"><\/span>4. C\u01a1 s\u1edf d\u1eef li\u1ec7u quan h\u1ec7<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>C\u01a1 s\u1edf d\u1eef li\u1ec7u quan h\u1ec7 l\u00e0 m\u1ed9t lo\u1ea1i c\u01a1 s\u1edf d\u1eef li\u1ec7u \u0111\u01b0\u1ee3c t\u1ed5 ch\u1ee9c theo m\u00f4 h\u00ecnh quan h\u1ec7, trong \u0111\u00f3 d\u1eef li\u1ec7u \u0111\u01b0\u1ee3c l\u01b0u tr\u1eef trong c\u00e1c b\u1ea3ng c\u00f3 m\u1ed1i quan h\u1ec7 v\u1edbi nhau. M\u1ed7i b\u1ea3ng \u0111\u1ea1i di\u1ec7n cho m\u1ed9t th\u1ef1c th\u1ec3 v\u00e0 c\u00e1c c\u1ed9t c\u1ee7a b\u1ea3ng \u0111\u1ea1i di\u1ec7n cho c\u00e1c thu\u1ed9c t\u00ednh c\u1ee7a th\u1ef1c th\u1ec3 \u0111\u00f3.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"41_Mo_hinh_quan_he\"><\/span>4.1 M\u00f4 h\u00ecnh quan h\u1ec7<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>M\u00f4 h\u00ecnh quan h\u1ec7 l\u00e0 m\u1ed9t ph\u01b0\u01a1ng ph\u00e1p \u0111\u1ec3 bi\u1ec3u di\u1ec5n v\u00e0 t\u1ed5 ch\u1ee9c d\u1eef li\u1ec7u trong c\u01a1 s\u1edf d\u1eef li\u1ec7u quan h\u1ec7. N\u00f3 s\u1eed d\u1ee5ng c\u00e1c b\u1ea3ng \u0111\u1ec3 l\u01b0u tr\u1eef th\u00f4ng tin v\u00e0 quan h\u1ec7 gi\u1eefa c\u00e1c b\u1ea3ng \u0111\u01b0\u1ee3c x\u00e1c \u0111\u1ecbnh th\u00f4ng qua kh\u00f3a ch\u00ednh v\u00e0 kh\u00f3a ngo\u1ea1i.<\/p>\n<h4><span class=\"ez-toc-section\" id=\"Uu_diem_cua_co_so_du_lieu_quan_he\"><\/span>\u01afu \u0111i\u1ec3m c\u1ee7a c\u01a1 s\u1edf d\u1eef li\u1ec7u quan h\u1ec7:<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<ul>\n<li>T\u00ednh to\u00e0n v\u1eb9n: C\u00e1c r\u00e0ng bu\u1ed9c kh\u00f3a ch\u00ednh v\u00e0 kh\u00f3a ngo\u1ea1i gi\u00fap duy tr\u00ec t\u00ednh to\u00e0n v\u1eb9n c\u1ee7a d\u1eef li\u1ec7u.<\/li>\n<li>T\u00ednh linh ho\u1ea1t: C\u1ea5u tr\u00fac b\u1ea3ng linh ho\u1ea1t cho ph\u00e9p thay \u0111\u1ed5i c\u1ea5u tr\u00fac c\u01a1 s\u1edf d\u1eef li\u1ec7u m\u00e0 kh\u00f4ng \u1ea3nh h\u01b0\u1edfng \u0111\u1ebfn d\u1eef li\u1ec7u hi\u1ec7n c\u00f3.<\/li>\n<li>T\u00ednh nh\u1ea5t qu\u00e1n: C\u01a1 s\u1edf d\u1eef li\u1ec7u quan h\u1ec7 \u0111\u1ea3m b\u1ea3o t\u00ednh nh\u1ea5t qu\u00e1n c\u1ee7a d\u1eef li\u1ec7u th\u00f4ng qua c\u00e1c r\u00e0ng bu\u1ed9c v\u00e0 quy t\u1eafc.<\/li>\n<\/ul>\n<h2><span class=\"ez-toc-section\" id=\"5_Bao_mat_co_so_du_lieu\"><\/span>5. B\u1ea3o m\u1eadt c\u01a1 s\u1edf d\u1eef li\u1ec7u<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p><img decoding=\"async\" alt=\"5. B\u1ea3o m\u1eadt c\u01a1 s\u1edf d\u1eef li\u1ec7u\" src=\"https:\/\/ungdung.hotronghiencuu.com\/open\/wp-content\/uploads\/2023\/09\/tim_hieu_ve_truy_van_co_so_du_lieu_va_cach_quan_ly_du_lieu_hieu_qua.jpg\" style=\"text-align: center; clear: both; display: block; margin: 0 auto;\" title=\"5. B\u1ea3o m\u1eadt c\u01a1 s\u1edf d\u1eef li\u1ec7u\"\/><\/p>\n<p>B\u1ea3o m\u1eadt c\u01a1 s\u1edf d\u1eef li\u1ec7u l\u00e0 qu\u00e1 tr\u00ecnh b\u1ea3o v\u1ec7 v\u00e0 b\u1ea3o m\u1eadt th\u00f4ng tin trong c\u01a1 s\u1edf d\u1eef li\u1ec7u kh\u1ecfi c\u00e1c m\u1ed1i \u0111e d\u1ecda v\u00e0 vi ph\u1ea1m an ninh. \u0110i\u1ec1u n\u00e0y bao g\u1ed3m x\u00e1c th\u1ef1c ng\u01b0\u1eddi d\u00f9ng, ki\u1ec3m so\u00e1t truy c\u1eadp, m\u00e3 h\u00f3a d\u1eef li\u1ec7u v\u00e0 gi\u00e1m s\u00e1t ho\u1ea1t \u0111\u1ed9ng trong c\u01a1 s\u1edf d\u1eef li\u1ec7u.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"51_Xac_thuc_nguoi_dung\"><\/span>5.1 X\u00e1c th\u1ef1c ng\u01b0\u1eddi d\u00f9ng<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>X\u00e1c th\u1ef1c ng\u01b0\u1eddi d\u00f9ng l\u00e0 qu\u00e1 tr\u00ecnh x\u00e1c minh danh t\u00ednh c\u1ee7a ng\u01b0\u1eddi d\u00f9ng khi truy c\u1eadp v\u00e0o c\u01a1 s\u1edf d\u1eef li\u1ec7u. \u0110i\u1ec1u n\u00e0y c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c th\u1ef1c hi\u1ec7n th\u00f4ng qua vi\u1ec7c y\u00eau c\u1ea7u t\u00ean \u0111\u0103ng nh\u1eadp v\u00e0 m\u1eadt kh\u1ea9u ho\u1eb7c s\u1eed d\u1ee5ng c\u00e1c ph\u01b0\u01a1ng ph\u00e1p x\u00e1c th\u1ef1c kh\u00e1c nh\u01b0 ch\u1ee9ng ch\u1ec9 s\u1ed1.<\/p>\n<h4><span class=\"ez-toc-section\" id=\"Cac_bien_phap_bao_mat_khac\"><\/span>C\u00e1c bi\u1ec7n ph\u00e1p b\u1ea3o m\u1eadt kh\u00e1c:<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<ul>\n<li>Ki\u1ec3m so\u00e1t truy c\u1eadp: Qu\u1ea3n l\u00fd quy\u1ec1n truy c\u1eadp c\u1ee7a ng\u01b0\u1eddi d\u00f9ng \u0111\u1ec3 ch\u1ec9 cho ph\u00e9p h\u1ecd truy c\u1eadp v\u00e0o c\u00e1c ph\u1ea7n c\u1ee7a c\u01a1 s\u1edf d\u1eef li\u1ec7u m\u00e0 h\u1ecd \u0111\u01b0\u1ee3c \u1ee7y quy\u1ec1n.<\/li>\n<li>M\u00e3 h\u00f3a d\u1eef li\u1ec7u: M\u00e3 h\u00f3a d\u1eef li\u1ec7u gi\u00fap b\u1ea3o v\u1ec7 th\u00f4ng tin nh\u1ea1y c\u1ea3m kh\u1ecfi vi\u1ec7c truy c\u1eadp tr\u00e1i ph\u00e9p.<\/li>\n<li>Gi\u00e1m s\u00e1t ho\u1ea1t \u0111\u1ed9ng: Theo d\u00f5i v\u00e0 ghi l\u1ea1i c\u00e1c ho\u1ea1t \u0111\u1ed9ng trong c\u01a1 s\u1edf d\u1eef li\u1ec7u \u0111\u1ec3 ph\u00e1t hi\u1ec7n v\u00e0 ng\u0103n ch\u1eb7n c\u00e1c h\u00e0nh vi \u0111\u00e1ng ng\u1edd.<\/li>\n<\/ul>\n<h2><span class=\"ez-toc-section\" id=\"6_Toi_uu_hoa_truy_van\"><\/span>6. T\u1ed1i \u01b0u h\u00f3a truy v\u1ea5n<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>T\u1ed1i \u01b0u h\u00f3a truy v\u1ea5n l\u00e0 qu\u00e1 tr\u00ecnh t\u00ecm ki\u1ebfm v\u00e0 tri\u1ec3n khai c\u00e1c ph\u01b0\u01a1ng ph\u00e1p t\u1ed1t nh\u1ea5t \u0111\u1ec3 th\u1ef1c hi\u1ec7n c\u00e1c c\u00e2u truy v\u1ea5n m\u1ed9t c\u00e1ch hi\u1ec7u qu\u1ea3 nh\u1eb1m t\u0103ng t\u1ed1c \u0111\u1ed9 x\u1eed l\u00fd v\u00e0 gi\u1ea3m t\u1ea3i cho c\u01a1 s\u1edf d\u1eef li\u1ec7u. \u0110i\u1ec1u n\u00e0y c\u00f3 th\u1ec3 bao g\u1ed3m vi\u1ec7c ch\u1ec9nh s\u1eeda c\u00e2u truy v\u1ea5n, t\u1ea1o ch\u1ec9 m\u1ee5c v\u00e0 thay \u0111\u1ed5i c\u1ea5u tr\u00fac b\u1ea3ng \u0111\u1ec3 n\u00e2ng cao hi\u1ec7u su\u1ea5t.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"61_Chinh_sua_cau_truy_van\"><\/span>6.1 Ch\u1ec9nh s\u1eeda c\u00e2u truy v\u1ea5n<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>M\u1ed9t s\u1ed1 k\u1ef9 thu\u1eadt ch\u1ec9nh s\u1eeda c\u00e2u truy v\u1ea5n c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c \u00e1p d\u1ee5ng \u0111\u1ec3 c\u1ea3i thi\u1ec7n hi\u1ec7u su\u1ea5t, v\u00ed d\u1ee5 nh\u01b0 s\u1eed d\u1ee5ng c\u00e1c to\u00e1n t\u1eed t\u1ed1i \u01b0u h\u01a1n, lo\u1ea1i b\u1ecf c\u00e1c c\u00e2u truy v\u1ea5n kh\u00f4ng c\u1ea7n thi\u1ebft v\u00e0 t\u1ed1i \u01b0u h\u00f3a \u0111i\u1ec1u ki\u1ec7n truy v\u1ea5n.<\/p>\n<h4><span class=\"ez-toc-section\" id=\"Cac_phuong_phap_toi_uu_hoa_khac\"><\/span>C\u00e1c ph\u01b0\u01a1ng ph\u00e1p t\u1ed1i \u01b0u h\u00f3a kh\u00e1c:<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<ul>\n<li>T\u1ea1o ch\u1ec9 m\u1ee5c: T\u1ea1o ch\u1ec9 m\u1ee5c cho c\u00e1c c\u1ed9t quan tr\u1ecdng trong b\u1ea3ng \u0111\u1ec3 gi\u1ea3m th\u1eddi gian truy xu\u1ea5t d\u1eef li\u1ec7u.<\/li>\n<li>Thay \u0111\u1ed5i c\u1ea5u tr\u00fac b\u1ea3ng: \u0110\u00f4i khi, vi\u1ec7c thay \u0111\u1ed5i c\u1ea5u tr\u00fac b\u1ea3ng nh\u01b0 chia th\u00e0nh nhi\u1ec1u b\u1ea3ng nh\u1ecf h\u01a1n ho\u1eb7c k\u1ebft h\u1ee3p c\u00e1c b\u1ea3ng c\u00f3 th\u1ec3 c\u1ea3i thi\u1ec7n hi\u1ec7u su\u1ea5t c\u1ee7a c\u00e2u truy v\u1ea5n.<\/li>\n<li>S\u1eed d\u1ee5ng cache: S\u1eed d\u1ee5ng cache \u0111\u1ec3 l\u01b0u k\u1ebft qu\u1ea3 c\u1ee7a c\u00e1c c\u00e2u truy v\u1ea5n \u0111\u00e3 \u0111\u01b0\u1ee3c th\u1ef1c hi\u1ec7n tr\u01b0\u1edbc \u0111\u00f3 v\u00e0 t\u00e1i s\u1eed d\u1ee5ng ch\u00fang khi c\u00f3 y\u00eau c\u1ea7u t\u01b0\u01a1ng t\u1ef1.<\/li>\n<\/ul>\n<p>Truy v\u1ea5n c\u01a1 s\u1edf d\u1eef li\u1ec7u l\u00e0 qu\u00e1 tr\u00ecnh t\u00ecm ki\u1ebfm th\u00f4ng tin t\u1eeb c\u01a1 s\u1edf d\u1eef li\u1ec7u b\u1eb1ng c\u00e2u l\u1ec7nh \u0111\u1eb7c bi\u1ec7t. N\u00f3 gi\u00fap ng\u01b0\u1eddi d\u00f9ng truy xu\u1ea5t v\u00e0 x\u1eed l\u00fd d\u1eef li\u1ec7u m\u1ed9t c\u00e1ch hi\u1ec7u qu\u1ea3, \u0111\u1ea3m b\u1ea3o t\u00ednh to\u00e0n v\u1eb9n v\u00e0 an to\u00e0n c\u1ee7a h\u1ec7 th\u1ed1ng. Qua \u0111\u00f3, truy v\u1ea5n c\u01a1 s\u1edf d\u1eef li\u1ec7u \u0111\u00f3ng vai tr\u00f2 quan tr\u1ecdng trong vi\u1ec7c ph\u00e2n t\u00edch v\u00e0 khai th\u00e1c th\u00f4ng tin.<br \/>\n<iframe loading=\"lazy\" title=\"B\u00e0i 7 :: SQL Truy v\u1ea5n d\u1eef li\u1ec7u\" width=\"790\" height=\"444\" src=\"https:\/\/www.youtube.com\/embed\/glDmJJzMX28?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" allowfullscreen><\/iframe><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Truy v\u1ea5n c\u01a1 s\u1edf d\u1eef li\u1ec7u l\u00e0 qu\u00e1 tr\u00ecnh t\u00ecm ki\u1ebfm th\u00f4ng tin t\u1eeb m\u1ed9t h\u1ec7 th\u1ed1ng l\u01b0u tr\u1eef d\u1eef li\u1ec7u. 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