{"id":8183,"date":"2023-10-07T22:44:09","date_gmt":"2023-10-07T15:44:09","guid":{"rendered":"https:\/\/teky.edu.vn\/blog\/?p=8183"},"modified":"2025-05-12T11:39:04","modified_gmt":"2025-05-12T04:39:04","slug":"cau-lenh-sql","status":"publish","type":"post","link":"https:\/\/teky.edu.vn\/blog\/cau-lenh-sql\/","title":{"rendered":"Kh\u00e1m ph\u00e1 SQL: Ng\u00f4n ng\u1eef l\u1eadp tr\u00ecnh quan tr\u1ecdng cho c\u00f4ng vi\u1ec7c v\u1edbi c\u01a1 s\u1edf d\u1eef li\u1ec7u"},"content":{"rendered":"\n\n<div class=\"kk-star-ratings kksr-auto kksr-align-left kksr-valign-top\"\n    data-payload='{&quot;align&quot;:&quot;left&quot;,&quot;id&quot;:&quot;8183&quot;,&quot;slug&quot;:&quot;default&quot;,&quot;valign&quot;:&quot;top&quot;,&quot;ignore&quot;:&quot;&quot;,&quot;reference&quot;:&quot;auto&quot;,&quot;class&quot;:&quot;&quot;,&quot;count&quot;:&quot;8&quot;,&quot;legendonly&quot;:&quot;&quot;,&quot;readonly&quot;:&quot;&quot;,&quot;score&quot;:&quot;4&quot;,&quot;starsonly&quot;:&quot;&quot;,&quot;best&quot;:&quot;5&quot;,&quot;gap&quot;:&quot;5&quot;,&quot;greet&quot;:&quot;Rate this post&quot;,&quot;legend&quot;:&quot;4\\\/5 - (8 b\u00ecnh ch\u1ecdn)&quot;,&quot;size&quot;:&quot;24&quot;,&quot;title&quot;:&quot;Kh\u00e1m ph\u00e1 SQL: Ng\u00f4n ng\u1eef l\u1eadp tr\u00ecnh quan tr\u1ecdng cho c\u00f4ng vi\u1ec7c v\u1edbi c\u01a1 s\u1edf d\u1eef li\u1ec7u&quot;,&quot;width&quot;:&quot;113.5&quot;,&quot;_legend&quot;:&quot;{score}\\\/{best} - ({count} {votes})&quot;,&quot;font_factor&quot;:&quot;1.25&quot;}'>\n            \n<div class=\"kksr-stars\">\n    \n<div class=\"kksr-stars-inactive\">\n            <div class=\"kksr-star\" data-star=\"1\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" data-star=\"2\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" data-star=\"3\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" data-star=\"4\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" data-star=\"5\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n    <\/div>\n    \n<div class=\"kksr-stars-active\" style=\"width: 113.5px;\">\n            <div class=\"kksr-star\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n    <\/div>\n<\/div>\n                \n\n<div class=\"kksr-legend\" style=\"font-size: 19.2px;\">\n            4\/5 - (8 b\u00ecnh ch\u1ecdn)    <\/div>\n    <\/div>\n<p style=\"text-align: justify;\"><em>Ng\u00f4n ng\u1eef l\u1eadp tr\u00ecnh l\u00e0 l\u0129nh v\u1ef1c kh\u00f4ng th\u1ec3 b\u1ecf qua khi l\u00e0m vi\u1ec7c trong ng\u00e0nh IT. C\u00f3 r\u1ea5t nhi\u1ec1u lo\u1ea1i ng\u00f4n ng\u1eef l\u1eadp tr\u00ecnh kh\u00e1c nhau. Vi\u1ec7c b\u1ea3n ph\u1ea3i h\u1ecdc lo\u1ea1i n\u00e0o l\u00e0 t\u00f9y theo y\u00eau c\u1ea7u c\u1ee7a c\u00f4ng vi\u1ec7c. N\u1ebfu hay ph\u1ea3i l\u00e0m vi\u1ec7c c\u00f9ng c\u01a1 s\u1edf d\u1eef li\u1ec7u, ch\u1eafc h\u1eb3n b\u1ea1n \u0111\u1ecdc s\u1ebd r\u1ea5t quen thu\u1ed9c v\u1edbi c\u00e1i t\u00ean SQL. V\u1eady ng\u00f4n ng\u1eef SOL l\u00e0 g\u00ec, c\u00f4ng d\u1ee5ng v\u00e0 c\u00e1ch t\u1ea1o <strong>c\u00e2u l\u1ec7nh SQL \u0111\u01a1n gi\u1ea3n<\/strong> ra sao? T\u1ea5t c\u1ea3 s\u1ebd c\u00f3 trong b\u00e0i vi\u1ebft sau.<\/em><\/p>\n<figure id=\"attachment_24877\" aria-describedby=\"caption-attachment-24877\" style=\"width: 600px\" class=\"wp-caption aligncenter\"><a href=\"http:\/\/hoclaptrinhmienphi.teky.vn\/1hhoclaptrinh\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-24877\" src=\"https:\/\/teky.edu.vn\/blog\/wp-content\/uploads\/2024\/03\/Banner-Free-Trial.png\" alt=\"H\u1ecdc th\u1eed mi\u1ec5n ph\u00ed\" width=\"600\" height=\"314\" \/><\/a><figcaption id=\"caption-attachment-24877\" class=\"wp-caption-text\">H\u1ecdc th\u1eed l\u1eadp tr\u00ecnh online mi\u1ec5n ph\u00ed t\u1ea1i Teky Edtech &#8211; Kh\u00e1m ph\u00e1 ti\u1ec1m n\u0103ng c\u00f4ng ngh\u1ec7 c\u1ee7a tr\u1ebb \u0111\u1ec3 d\u1eabn \u0111\u1ea7u t\u01b0\u01a1ng lai<\/figcaption><\/figure>\n<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_76 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\" style=\"cursor:inherit\">N\u1ed9i dung <\/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\" aria-label=\"Toggle Table of Content\"><span class=\"ez-toc-js-icon-con\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><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><\/span><\/span><\/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:\/\/teky.edu.vn\/blog\/cau-lenh-sql\/#Gioi_thieu_chung_ve_SQL\" >Gi\u1edbi thi\u1ec7u chung v\u1ec1 SQL<\/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:\/\/teky.edu.vn\/blog\/cau-lenh-sql\/#Dinh_nghia_SQL_can_ban\" >\u0110\u1ecbnh ngh\u0129a SQL c\u0103n b\u1ea3n<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/teky.edu.vn\/blog\/cau-lenh-sql\/#Lich_su_hinh_thanh_cua_cau_lenh_SQL\" >L\u1ecbch s\u1eed h\u00ecnh th\u00e0nh c\u1ee7a c\u00e2u l\u1ec7nh SQL<\/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:\/\/teky.edu.vn\/blog\/cau-lenh-sql\/#Chuc_nang_cua_cau_lenh_SQL\" >Ch\u1ee9c n\u0103ng c\u1ee7a c\u00e2u l\u1ec7nh SQL<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/teky.edu.vn\/blog\/cau-lenh-sql\/#Phan_loai_cau_lenh_SQL\" >Ph\u00e2n lo\u1ea1i c\u00e2u l\u1ec7nh SQL<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/teky.edu.vn\/blog\/cau-lenh-sql\/#Data_Definition_Language\" >Data Definition Language<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/teky.edu.vn\/blog\/cau-lenh-sql\/#Data_Manipulation_Language\" >Data Manipulation Language<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"https:\/\/teky.edu.vn\/blog\/cau-lenh-sql\/#Data_Control_Language\" >Data Control Language<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-9\" href=\"https:\/\/teky.edu.vn\/blog\/cau-lenh-sql\/#Mot_so_cau_lenh_truy_van_SQL_hay_duoc_su_dung\" >M\u1ed9t s\u1ed1 c\u00e2u l\u1ec7nh truy v\u1ea5n SQL hay \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-10\" href=\"https:\/\/teky.edu.vn\/blog\/cau-lenh-sql\/#Truy_van_Update\" >Truy v\u1ea5n Update<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-11\" href=\"https:\/\/teky.edu.vn\/blog\/cau-lenh-sql\/#Truy_van_Insert_%E2%80%93_cau_lenh_SQL\" >Truy v\u1ea5n Insert &#8211; c\u00e2u l\u1ec7nh SQL<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-12\" href=\"https:\/\/teky.edu.vn\/blog\/cau-lenh-sql\/#Truy_van_Select\" >Truy v\u1ea5n Select<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-13\" href=\"https:\/\/teky.edu.vn\/blog\/cau-lenh-sql\/#Menh_de_Distinct\" >M\u1ec7nh \u0111\u1ec1 Distinct<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-14\" href=\"https:\/\/teky.edu.vn\/blog\/cau-lenh-sql\/#Thong_tin_co_ban_ve_Hoc_vien_chuyen_dao_tao_cong_nghe_va_lap_trinh_%E2%80%93_Teky\" >Th\u00f4ng tin c\u01a1 b\u1ea3n v\u1ec1 H\u1ecdc vi\u1ec7n chuy\u00ean \u0111\u00e0o t\u1ea1o c\u00f4ng ngh\u1ec7 v\u00e0 l\u1eadp tr\u00ecnh &#8211; Teky\u00a0<\/a><ul class='ez-toc-list-level-4' ><li class='ez-toc-heading-level-4'><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:\/\/teky.edu.vn\/blog\/cau-lenh-sql\/#Day_la_chuong_trinh_khong_chi_trang_bi_kien_thuc_lap_trinh_ma_con_ren_luyen_nhom_ky_nang_4Cs_Tre_se_duoc\" >\u0110\u00e2y l\u00e0 ch\u01b0\u01a1ng tr\u00ecnh kh\u00f4ng ch\u1ec9 trang b\u1ecb ki\u1ebfn th\u1ee9c l\u1eadp tr\u00ecnh m\u00e0 c\u00f2n r\u00e8n luy\u1ec7n nh\u00f3m k\u1ef9 n\u0103ng 4Cs. Tr\u1ebb s\u1ebd \u0111\u01b0\u1ee3c:<\/a><\/li><\/ul><\/li><\/ul><\/li><\/ul><\/nav><\/div>\n<h2 style=\"text-align: justify;\"><span class=\"ez-toc-section\" id=\"Gioi_thieu_chung_ve_SQL\"><\/span>Gi\u1edbi thi\u1ec7u chung v\u1ec1 SQL<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<h3 style=\"text-align: justify;\"><span class=\"ez-toc-section\" id=\"Dinh_nghia_SQL_can_ban\"><\/span>\u0110\u1ecbnh ngh\u0129a SQL c\u0103n b\u1ea3n<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p style=\"text-align: justify;\">SQL l\u00e0 t\u00ean vi\u1ebft t\u1eaft c\u1ee7a Structured Query Language. SQL c\u01a1 b\u1ea3n l\u00e0 m\u1ed9t lo\u1ea1i ng\u00f4n ng\u1eef truy v\u1ea5n c\u00f3 c\u1ea5u tr\u00fac cho ph\u00e9p ng\u01b0\u1eddi d\u00f9ng th\u1ef1c hi\u1ec7n nh\u1eefng t\u01b0\u01a1ng t\u00e1c nh\u1ea5t \u0111\u1ecbnh v\u1edbi c\u01a1 s\u1edf d\u1eef li\u1ec7u. Ng\u00f4n ng\u1eef truy v\u1ea5n SQL \u0111\u01b0\u1ee3c ANSI (American National Standards Institute) hay c\u00f2n g\u1ecdi l\u00e0 Vi\u1ec7n ti\u00eau chu\u1ea9n qu\u1ed1c gia Hoa K\u1ef3 c\u1ea5p ph\u00e9p ti\u00eau chu\u1ea9n h\u00f3a. Ch\u00ednh v\u00ec th\u1ebf n\u00ean n\u00f3 \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng nh\u01b0 m\u1ed9t ng\u00f4n ng\u1eef m\u00e1y t\u00ednh ch\u00ednh th\u1ed1ng trong l\u0129nh v\u1ef1c qu\u1ea3n l\u00fd c\u01a1 s\u1edf d\u1eef li\u1ec7u quan h\u1ec7. SQL \u0111\u01b0\u1ee3c r\u1ea5t nhi\u1ec1u c\u00f4ng ty v\u00e0 t\u1eadp \u0111o\u00e0n l\u1edbn trong l\u0129nh v\u1ef1c c\u00f4ng ngh\u1ec7 s\u1eed d\u1ee5ng b\u1edfi h\u00e0ng lo\u1ea1t \u01b0u \u0111i\u1ec3m tuy\u1ec7t v\u1eddi.<\/p>\n<p style=\"text-align: justify;\">SQL \u0111\u00f3ng vai tr\u00f2 l\u00e0 ng\u00f4n ng\u1eef ch\u00ednh trong c\u00e1c h\u1ec7 \u0111i\u1ec1u h\u00e0nh v\u00e0 qu\u1ea3n l\u00fd d\u1eef li\u1ec7u quan h\u1ec7 RDBMS nh\u01b0 Oracle, MS Access, MySQL, Informix, SQL Sever\u2026 \u0110\u00f3 c\u0169ng l\u00e0 l\u00fd do t\u1ea1i sao SQL l\u1ea1i ph\u1ed5 bi\u1ebfn \u0111\u1ebfn th\u1ebf. N\u00f3 t\u01b0\u01a1ng th\u00edch \u0111\u01b0\u1ee3c v\u1edbi nhi\u1ec1u ph\u1ea7n m\u1ec1m, \u1ee9ng d\u1ee5ng v\u00e0 ho\u1ea1t \u0111\u1ed9ng \u1ed5n \u0111\u1ecbnh tr\u00ean nhi\u1ec1u n\u1ec1n t\u1ea3ng kh\u00e1c nhau.<\/p>\n<p><em>Xem th\u00eam: <a href=\"https:\/\/teky.edu.vn\/blog\/ngon-ngu-sql\/\">Ng\u00f4n ng\u1eef SQL l\u00e0 g\u00ec? Gi\u1edbi thi\u1ec7u m\u1ed9t s\u1ed1 lo\u1ea1i l\u1ec7nh c\u01a1 b\u1ea3n c\u1ee7a SQL<\/a><\/em><\/p>\n<figure id=\"attachment_8188\" aria-describedby=\"caption-attachment-8188\" style=\"width: 650px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-8188\" src=\"https:\/\/teky.edu.vn\/blog\/wp-content\/uploads\/2021\/07\/vi-du-ve-cau-lenh-sql.jpg\" alt=\"V\u00ed d\u1ee5 v\u1ec1 c\u00e2u l\u1ec7nh SQL\" width=\"650\" height=\"400\" srcset=\"https:\/\/teky.edu.vn\/blog\/wp-content\/uploads\/2021\/07\/vi-du-ve-cau-lenh-sql.jpg 650w, https:\/\/teky.edu.vn\/blog\/wp-content\/uploads\/2021\/07\/vi-du-ve-cau-lenh-sql-400x246.jpg 400w\" sizes=\"auto, (max-width: 650px) 100vw, 650px\" \/><figcaption id=\"caption-attachment-8188\" class=\"wp-caption-text\">V\u00ed d\u1ee5 v\u1ec1 c\u00e2u l\u1ec7nh SQL<\/figcaption><\/figure>\n<h3 style=\"text-align: justify;\"><span class=\"ez-toc-section\" id=\"Lich_su_hinh_thanh_cua_cau_lenh_SQL\"><\/span>L\u1ecbch s\u1eed h\u00ecnh th\u00e0nh c\u1ee7a c\u00e2u l\u1ec7nh SQL<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p style=\"text-align: justify;\">M\u1ed9t trong nh\u1eefng l\u00fd do khi\u1ebfn SQL l\u1ea1i c\u00f3 ch\u1ed7 \u0111\u1ee9ng v\u1eefng ch\u1eafc nh\u01b0 v\u1eady trong ng\u00e0nh c\u00f4ng ngh\u1ec7 m\u00e1y t\u00ednh l\u00e0 v\u00ec n\u00f3 \u0111\u00e3 c\u00f3 l\u1ecbch s\u1eed ph\u00e1t tri\u1ec3n v\u00f4 c\u00f9ng l\u00e2u \u0111\u1eddi. SQL b\u1eaft \u0111\u1ea7u xu\u1ea5t hi\u1ec7n t\u1eeb n\u0103m 1970 khi m\u00e0 cha \u0111\u1ebb c\u1ee7a c\u01a1 s\u1edf d\u1eef li\u1ec7u quan h\u1ec7 l\u00e0 Dr.Edgar F.Ted Codd s\u1eed d\u1ee5ng. \u00d4ng l\u00e0 m\u1ed9t nh\u00e0 ph\u00e1t tri\u1ec3n c\u01a1 s\u1edf d\u1eef li\u1ec7u l\u00e0m vi\u1ec7c t\u1ea1i IBM. \u0110\u1ec3 qu\u00e1 tr\u00ecnh l\u00e0m vi\u1ec7c v\u1edbi Relational Database tr\u1edf n\u00ean \u0111\u01a1n gi\u1ea3n h\u01a1n, \u00f4ng \u0111\u00e3 ph\u00e1t minh ra c\u00e1c c\u00e2u l\u1ec7nh SQL.<\/p>\n<p style=\"text-align: justify;\">Tuy nhi\u00ean, cho \u0111\u1ebfn n\u0103m 1974, SQL m\u1edbi ch\u00ednh th\u1ee9c \u0111\u01b0\u1ee3c c\u00f4ng b\u1ed1 tr\u00ean th\u1ebf gi\u1edbi. N\u00f3 nhanh ch\u00f3ng \u0111\u01b0\u1ee3c nhi\u1ec1u ng\u01b0\u1eddi bi\u1ebft \u0111\u1ebfn v\u00e0 s\u1eed d\u1ee5ng. C\u00e2u l\u1ec7nh SQL \u0111\u00e3 mang \u0111\u1ebfn m\u1ed9t c\u1ea3i ti\u1ebfn m\u1edbi cho l\u0129nh v\u1ef1c c\u01a1 s\u1edf d\u1eef li\u1ec7u, v\u1ed1n lu\u00f4n l\u00e0 b\u00e0i to\u00e1n kh\u00f3 v\u00ec vi\u1ec7c qu\u1ea3n l\u00fd m\u1ed9t l\u01b0\u1ee3ng th\u00f4ng tin kh\u1ed5ng l\u1ed3 kh\u00f4ng ph\u1ea3i l\u00e0 \u0111i\u1ec1u d\u1ec5 d\u00e0ng.<\/p>\n<figure id=\"attachment_24875\" aria-describedby=\"caption-attachment-24875\" style=\"width: 600px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/lotrinhlaptrinh.teky.vn\/\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-24875\" src=\"https:\/\/teky.edu.vn\/blog\/wp-content\/uploads\/2024\/03\/Sale-Promotion.png\" alt=\"\u01afu \u0111\u00e3i \u0111\u1ebfn 25%\" width=\"600\" height=\"314\" \/><\/a><figcaption id=\"caption-attachment-24875\" class=\"wp-caption-text\">H\u1ecdc l\u1eadp tr\u00ecnh online cho tr\u1ebb em t\u1eeb s\u1edbm &#8211; H\u00e0nh trang \u0111\u00f3n \u0111\u1ea7u t\u01b0\u01a1ng lai<\/figcaption><\/figure>\n<p style=\"text-align: justify;\">\u0110\u1ebfn n\u0103m 1978, c\u00f4ng ty ch\u1ee7 qu\u1ea3n c\u1ee7a Dr.Edgar F.Ted Codd c\u00f4ng b\u1ed1 m\u1ed9t m\u00f4 h\u00ecnh \u1ee9ng d\u1ee5ng SQL d\u1ef1a tr\u00ean \u00fd t\u01b0\u1edfng c\u1ee7a \u00f4ng. \u1ee8ng d\u1ee5ng n\u00e0y c\u00f3 t\u00ean l\u00e0 System\/R. C\u00e1c t\u00ednh n\u0103ng s\u01a1 khai \u0111\u01b0\u1ee3c ph\u00e1t tri\u1ec3n v\u00e0 c\u1ea3i ti\u1ebfn nhi\u1ec1u h\u01a1n tr\u01b0\u1edbc khi \u0111\u01b0a ra th\u1ecb tr\u01b0\u1eddng m\u1ed9t c\u00e1ch ch\u00ednh th\u1ee9c.<\/p>\n<p style=\"text-align: justify;\">N\u0103m 1986, IBM m\u1edbi ch\u00ednh th\u1ee9c ho\u00e0n thi\u1ec7n \u0111\u01b0\u1ee3c h\u1ec7 th\u1ed1ng SQL c\u1ee7a ri\u00eang m\u00ecnh v\u00e0 \u0111\u01b0\u1ee3c ANSI chu\u1ea9n h\u00f3a.<\/p>\n<p><em>Xem th\u00eam:<a href=\"https:\/\/teky.edu.vn\/blog\/sql-injection-la-gi\/\"> SQL Injection l\u00e0 g\u00ec? 3 c\u00e1ch ph\u00f2ng ch\u1ed1ng SQL Injection hi\u1ec7u qu\u1ea3<\/a><\/em><\/p>\n<h2 style=\"text-align: justify;\"><span class=\"ez-toc-section\" id=\"Chuc_nang_cua_cau_lenh_SQL\"><\/span>Ch\u1ee9c n\u0103ng c\u1ee7a c\u00e2u l\u1ec7nh SQL<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p style=\"text-align: justify;\">Kh\u00f4ng ph\u1ea3i t\u1ef1 nhi\u00ean m\u00e0 c\u00e1c c\u00e2u l\u1ec7nh SQL l\u1ea1i \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng ph\u1ed5 bi\u1ebfn nh\u01b0 th\u1ebf. SQL mang \u0111\u1ebfn r\u1ea5t nhi\u1ec1u ch\u1ee9c n\u0103ng h\u1eefu d\u1ee5ng trong ng\u00e0nh c\u00f4ng ngh\u1ec7 th\u00f4ng tin. Nh\u00ecn chung, SQL s\u1ebd h\u1ed7 tr\u1ee3 con ng\u01b0\u1eddi trong vi\u1ec7c qu\u1ea3n l\u00fd v\u00e0 thao t\u00e1c v\u1edbi s\u1ed1 d\u1eef li\u1ec7u kh\u1ed5ng l\u1ed3, v\u1ed1n l\u00e0 c\u00f4ng vi\u1ec7c m\u1ea5t r\u1ea5t nhi\u1ec1u th\u1eddi gian v\u00e0 chi ph\u00ed trong qu\u00e1 kh\u1ee9.<\/p>\n<p style=\"text-align: justify;\">Th\u00f4ng qua c\u00e1c c\u00e2u l\u1ec7nh SQL, ng\u01b0\u1eddi d\u00f9ng c\u00f3 th\u1ec3 truy c\u1eadp d\u1eef li\u1ec7u trong c\u00e1c kho qu\u1ea3n l\u00fd d\u1eef li\u1ec7u quan h\u1ec7. Ng\u01b0\u1eddi d\u00f9ng c\u0169ng c\u00f3 th\u1ec3 th\u1ef1c hi\u1ec7n nh\u1eefng thao t\u00e1c nh\u01b0 m\u00f4 t\u1ea3 d\u1eef li\u1ec7u, x\u00e1c \u0111\u1ecbnh d\u1eef li\u1ec7u\u2026 b\u1eb1ng SQL.<\/p>\n<p style=\"text-align: justify;\">SQL c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c nh\u00fang v\u00e0o c\u00e1c ng\u00f4n ng\u1eef s\u1eed d\u1ee5ng modules SQL, tr\u00ecnh bi\u00ean d\u1ecbch v\u00e0 th\u01b0 vi\u1ec7n. Ngo\u00e0i ra, ng\u00f4n ng\u1eef SQL c\u0169ng cho ph\u00e9p th\u1ef1c hi\u1ec7n c\u00e1c thao t\u00e1c v\u1edbi b\u1ea3ng v\u00e0 database nh\u01b0: kh\u1edfi t\u1ea1o, t\u1ea3i d\u1eef li\u1ec7u, t\u1ea1o ch\u1ebf \u0111\u1ed9 view, t\u1ea1o th\u1ee7 t\u1ee5c l\u01b0u tr\u1eef, c\u00e0i \u0111\u1eb7t plugin, thi\u1ebft l\u1eadp quy\u1ec1n truy c\u1eadp\u2026<\/p>\n<p style=\"text-align: justify;\">N\u00f3i chung, SQL cung c\u1ea5p cho ng\u01b0\u1eddi d\u00f9ng r\u1ea5t nhi\u1ec1u c\u00f4ng c\u1ee5 h\u1eefu \u00edch \u0111\u1ec3 th\u1ef1c hi\u1ec7n c\u00e1c c\u00f4ng vi\u1ec7c li\u00ean quan \u0111\u1ebfn l\u01b0\u1ee3ng th\u00f4ng tin l\u1edbn v\u00e0 ph\u1ee9c t\u1ea1p. Song song v\u1edbi \u0111\u00f3, ng\u00f4n ng\u1eef truy v\u1ea5n n\u00e0y c\u0169ng gi\u00fap ta c\u00f3 m\u1ed9t c\u00e1i nh\u00ecn to\u00e0n di\u1ec7n h\u01a1n v\u1edbi h\u1ec7 th\u1ed1ng qu\u1ea3n l\u00fd d\u1eef li\u1ec7u. T\u1eeb nh\u1eefng ch\u1ee9c n\u0103ng tuy\u1ec7t v\u1eddi c\u1ee7a ng\u00f4n ng\u1eef n\u00e0y ta r\u00fat ra \u0111\u01b0\u1ee3c h\u1ecdc c\u01a1 s\u1edf d\u1eef li\u1ec7u SQL ch\u1ec9 c\u00f3 l\u1ee3i ch\u1ee9 kh\u00f4ng c\u00f3 h\u1ea1i.<\/p>\n<h2 style=\"text-align: justify;\"><span class=\"ez-toc-section\" id=\"Phan_loai_cau_lenh_SQL\"><\/span>Ph\u00e2n lo\u1ea1i c\u00e2u l\u1ec7nh SQL<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p style=\"text-align: justify;\">C\u00f3 r\u1ea5t nhi\u1ec1u d\u1ea1ng c\u00e2u l\u1ec7nh SQL kh\u00e1c nhau. Tuy nhi\u00ean ch\u00fang \u0111\u01b0\u1ee3c quy th\u00e0nh 3 ph\u00e2n lo\u1ea1i ch\u00ednh l\u00e0: SQL DDL, SQL DML v\u00e0 SQL DCL.<\/p>\n<h3 style=\"text-align: justify;\"><span class=\"ez-toc-section\" id=\"Data_Definition_Language\"><\/span>Data Definition Language<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p style=\"text-align: justify;\">Data Definition Language c\u00f3 ngh\u0129a l\u00e0 ng\u00f4n ng\u1eef \u0111\u1ecbnh ngh\u0129a d\u1eef li\u1ec7u. Lo\u1ea1i l\u1ec7nh n\u00e0y cho ph\u00e9p ng\u01b0\u1eddi d\u00f9ng th\u1ef1c hi\u1ec7n c\u00e1c t\u01b0\u01a1ng t\u00e1c v\u1edbi b\u1ea3ng ho\u1eb7c c\u00e1c \u0111\u1ed1i t\u01b0\u1ee3ng kh\u00e1c trong Databases. DDL s\u1edf h\u1eefu 3 d\u1ea1ng l\u1ec7nh nh\u01b0 sau:<\/p>\n<ul style=\"text-align: justify;\">\n<li style=\"font-weight: 400;\" aria-level=\"1\">L\u1ec7nh CREATE: L\u1ec7nh n\u00e0y d\u00f9ng \u0111\u1ec3 kh\u1edfi t\u1ea1o m\u1ed9t b\u1ea3ng m\u1edbi. N\u00f3 c\u0169ng cho ph\u00e9p b\u1eadt view c\u1ee7a b\u1ea3ng ho\u1eb7c c\u00e1c \u0111\u1ed1i t\u01b0\u1ee3ng t\u01b0\u01a1ng t\u1ef1 trong c\u01a1 s\u1edf d\u1eef li\u1ec7u.<\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\">L\u1ec7nh ALTER: N\u1ebfu Create cho ph\u00e9p kh\u1edfi t\u1ea1i th\u00ec Alter s\u1ebd cho ph\u00e9p ch\u1ec9nh s\u1eeda. C\u00e1c \u0111\u1ed1i t\u01b0\u1ee3ng \u1ee9ng d\u1ee5ng c\u0169ng gi\u1ed1ng nh\u01b0 Create.<\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\">L\u1ec7nh DROP: Cho ph\u00e9p x\u00f3a ho\u00e0n to\u00e0n m\u1ed9t b\u1ea3ng, m\u1ed9t view b\u1ea3ng ho\u1eb7c m\u1ed9t \u0111\u1ed1i t\u01b0\u1ee3ng kh\u00e1c trong c\u01a1 s\u1edf d\u1eef li\u1ec7u.<\/li>\n<\/ul>\n<figure id=\"attachment_24867\" aria-describedby=\"caption-attachment-24867\" style=\"width: 600px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/khuyenmai.teky.vn\/tangsachlaptrinh\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-24867\" src=\"https:\/\/teky.edu.vn\/blog\/wp-content\/uploads\/2025\/04\/Artboard-5.png\" alt=\"tang-sach-lap-trinh-cho-be\" width=\"600\" height=\"314\" \/><\/a><figcaption id=\"caption-attachment-24867\" class=\"wp-caption-text\">Nh\u1eadn s\u00e1ch l\u1eadp tr\u00ecnh mi\u1ec5n ph\u00ed &#8211; M\u1edf ra th\u1ebf gi\u1edbi c\u00f4ng ngh\u1ec7 cho tr\u1ebb<\/figcaption><\/figure>\n<p><em>Xem th\u00eam : <a href=\"https:\/\/teky.edu.vn\/blog\/sql-la-gi\/\">SQL l\u00e0 g\u00ec? T\u1ea1i sao b\u1ea1n n\u00ean h\u1ecdc ph\u01b0\u01a1ng ph\u00e1p l\u1eadp tr\u00ecnh SQL?<\/a><\/em><\/p>\n<h3 style=\"text-align: justify;\"><span class=\"ez-toc-section\" id=\"Data_Manipulation_Language\"><\/span>Data Manipulation Language<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p style=\"text-align: justify;\">Data Manipulation Language c\u00f3 ngh\u0129a l\u00e0 ng\u00f4n ng\u1eef thao t\u00e1c d\u1eef li\u1ec7u. DML c\u00f3 kh\u1ea3 n\u0103ng th\u1ef1c hi\u1ec7n t\u00e1c \u0111\u1ed9ng \u0111\u1ebfn c\u00e1c b\u1ea3ng v\u00e0 b\u1ea3n ghi. DML s\u1edf h\u1eefu 4 d\u1ea1ng l\u1ec7nh nh\u01b0 sau:<\/p>\n<ul style=\"text-align: justify;\">\n<li style=\"font-weight: 400;\" aria-level=\"1\">L\u1ec7nh SELECT: Tr\u00edch xu\u1ea5t c\u00e1c b\u1ea3n ghi chi ti\u1ebft t\u1eeb m\u1ed9t ho\u1eb7c nhi\u1ec1u b\u1ea3ng.<\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\">L\u1ec7nh INSERT: B\u1eaft \u0111\u1ea7u m\u1ed9t b\u1ea3n ghi.<\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\">L\u1ec7nh UPDATE: S\u1eeda \u0111\u1ed5i c\u00e1c b\u1ea3n ghi.<\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\">L\u1ec7nh DELETE: X\u00f3a b\u1ea3n ghi.<\/li>\n<\/ul>\n<figure id=\"attachment_8186\" aria-describedby=\"caption-attachment-8186\" style=\"width: 650px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-8186\" src=\"https:\/\/teky.edu.vn\/blog\/wp-content\/uploads\/2021\/07\/sql-dong-vai-tro-rat-quan-trong.jpg\" alt=\"SQL \u0111\u00f3ng vai tr\u00f2 r\u1ea5t quan tr\u1ecdng\" width=\"650\" height=\"400\" srcset=\"https:\/\/teky.edu.vn\/blog\/wp-content\/uploads\/2021\/07\/sql-dong-vai-tro-rat-quan-trong.jpg 650w, https:\/\/teky.edu.vn\/blog\/wp-content\/uploads\/2021\/07\/sql-dong-vai-tro-rat-quan-trong-400x246.jpg 400w\" sizes=\"auto, (max-width: 650px) 100vw, 650px\" \/><figcaption id=\"caption-attachment-8186\" class=\"wp-caption-text\">SQL \u0111\u00f3ng vai tr\u00f2 r\u1ea5t quan tr\u1ecdng<\/figcaption><\/figure>\n<h3 style=\"text-align: justify;\"><span class=\"ez-toc-section\" id=\"Data_Control_Language\"><\/span>Data Control Language<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p style=\"text-align: justify;\">Data Control Language c\u00f3 ngh\u0129a l\u00e0 ng\u00f4n ng\u1eef \u0111i\u1ec1u khi\u1ec3n d\u1eef li\u1ec7u. Kh\u00e1c v\u1edbi 2 lo\u1ea1i l\u1ec7nh tr\u00ean, DCL gi\u00fap ng\u01b0\u1eddi d\u00f9ng c\u00e0i \u0111\u1eb7t c\u00e1c quy\u1ec1n truy c\u1eadp. DCL s\u1edf h\u1eefu 2 d\u1ea1ng l\u1ec7nh nh\u01b0 sau:<\/p>\n<ul style=\"text-align: justify;\">\n<li style=\"font-weight: 400;\" aria-level=\"1\">L\u1ec7nh GRANT: C\u1ea5p m\u1ed9t quy\u1ec1n t\u1edbi ng\u01b0\u1eddi d\u00f9ng.<\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\">L\u1ec7nh REVOKE: T\u1ecbch thu m\u1ed9t quy\u1ec1n \u0111\u00e3 c\u1ea5p cho ng\u01b0\u1eddi d\u00f9ng.<\/li>\n<\/ul>\n<p><em>M\u1eddi b\u1ea1n tham kh\u1ea3o th\u00eam: <a class=\"LinkSuggestion__Link-sc-1gewdgc-4 evyocv\" href=\"https:\/\/teky.edu.vn\/blog\/cac-loai-tinh-cach-mbti\/\" target=\"_blank\" rel=\"noopener\">C\u00e1c lo\u1ea1i t\u00ednh c\u00e1ch MBTI l\u00e0 g\u00ec &#8211; Con b\u1ea1n thu\u1ed9c nh\u00f3m n\u00e0o?<\/a><\/em><\/p>\n<h2 style=\"text-align: justify;\"><span class=\"ez-toc-section\" id=\"Mot_so_cau_lenh_truy_van_SQL_hay_duoc_su_dung\"><\/span>M\u1ed9t s\u1ed1 c\u00e2u l\u1ec7nh truy v\u1ea5n SQL hay \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<h3 style=\"text-align: justify;\"><span class=\"ez-toc-section\" id=\"Truy_van_Update\"><\/span>Truy v\u1ea5n Update<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p style=\"text-align: justify;\">C\u00e2u truy v\u1ea5n SQL Update \u0111\u01b0\u1ee3c d\u00f9ng \u0111\u1ec3 ch\u1ec9nh s\u1eeda c\u00e1c b\u1ea3n ghi \u0111ang hi\u1ec7n h\u1eefu trong m\u1ed9t b\u1ea3ng b\u1ea5t k\u1ef3. \u0110\u1ec3 x\u00e1c \u0111\u1ecbnh v\u1ecb tr\u00ed b\u1ea3n ghi c\u1ea7n s\u1eeda, ta c\u1ea7n gh\u00e9p c\u00e2u l\u1ec7nh Update v\u1edbi m\u1ec7nh \u0111\u1ec1 Where, n\u1ebfu kh\u00f4ng th\u00ec h\u1ec7 th\u1ed1ng s\u1ebd m\u1eb7c \u0111\u1ecbnh l\u00e0 to\u00e0n b\u1ed9 b\u1ea3n ghi c\u1ea7n s\u1eeda.<\/p>\n<p style=\"text-align: justify;\">C\u00fa ph\u00e1p c\u00e2u l\u1ec7nh Update nh\u01b0 sau:<\/p>\n<p style=\"text-align: justify;\">UPDATE ten_bang<\/p>\n<p style=\"text-align: justify;\">SET cot1 = giatri1, cot2 = giatri2&#8230;., cotN = giatriN<\/p>\n<p style=\"text-align: justify;\">WHERE [dieu_kien];<\/p>\n<h3 style=\"text-align: justify;\"><span class=\"ez-toc-section\" id=\"Truy_van_Insert_%E2%80%93_cau_lenh_SQL\"><\/span>Truy v\u1ea5n Insert &#8211; c\u00e2u l\u1ec7nh SQL<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p style=\"text-align: justify;\">Gi\u1ed1ng nh\u01b0 t\u00ean g\u1ecdi c\u1ee7a n\u00f3, c\u00e2u l\u1ec7nh In trong SQL \u0111\u01b0\u1ee3c d\u00f9ng \u0111\u1ec3 t\u1ea3i th\u00eam d\u1eef li\u1ec7u l\u00ean m\u1ed9t b\u1ea3ng trong Databases. C\u00e1c d\u1eef li\u1ec7u \u0111\u01b0\u1ee3c t\u1ea3i tu\u1ea7n t\u1ef1 theo c\u1ed9t m\u00e0 b\u1ea1n l\u1ef1a ch\u1ecdn. C\u00f3 hai c\u00e1ch \u0111\u1ec3 th\u00eam d\u1eef li\u1ec7u b\u1eb1ng Insert: ho\u1eb7c l\u00e0 th\u00eam trong m\u1ed9t c\u1ed9t, ho\u1eb7c l\u00e0 th\u00eam trong t\u1ea5t c\u1ea3 c\u00e1c c\u1ed9t.<\/p>\n<p style=\"text-align: justify;\">C\u00fa ph\u00e1p c\u00e2u l\u1ec7nh Insert nh\u01b0 sau:<\/p>\n<ul style=\"text-align: justify;\">\n<li style=\"font-weight: 400;\" aria-level=\"1\">Th\u00eam d\u1eef li\u1ec7u cho m\u1ed9t c\u1ed9t x\u00e1c \u0111\u1ecbnh<\/li>\n<\/ul>\n<p style=\"text-align: justify;\">INSERT INTO TABLE_TEN (cot1, cot2, cot3,&#8230;cotN)]<\/p>\n<p style=\"text-align: justify;\">VALUES (giatri1, giatri2, giatri3,&#8230;giatriN);<\/p>\n<ul style=\"text-align: justify;\">\n<li style=\"font-weight: 400;\" aria-level=\"1\">Th\u00eam d\u1eef li\u1ec7u cho t\u1ea5t c\u1ea3 c\u00e1c c\u1ed9t trong b\u1ea3ng<\/li>\n<\/ul>\n<p style=\"text-align: justify;\">INSERT INTO TABLE_TEN VALUES (giatri1,giatri2,giatri3,&#8230;giatriN);<\/p>\n<h3 style=\"text-align: justify;\"><span class=\"ez-toc-section\" id=\"Truy_van_Select\"><\/span>Truy v\u1ea5n Select<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p style=\"text-align: justify;\">C\u00e2u l\u1ec7nh Select trong SQL \u0111\u01b0\u1ee3c d\u00f9ng \u0111\u1ec3 tr\u00edch xu\u1ea5t m\u1ed9t ph\u1ea7n d\u1eef li\u1ec7u trong Databases th\u00e0nh d\u1ea1ng b\u1ea3ng d\u1eef li\u1ec7u k\u1ebft qu\u1ea3. L\u1ec7nh n\u00e0y \u0111\u01b0\u1ee3c th\u1ef1c hi\u1ec7n \u0111\u1ec3 gi\u00fap ng\u01b0\u1eddi d\u00f9ng c\u00f3 th\u1ec3 th\u1ed1ng k\u00ea d\u1eef li\u1ec7u m\u1ed9t c\u00e1ch d\u1ec5 d\u00e0ng h\u01a1n. C\u0169ng gi\u1ed1ng nh\u01b0 Insert, Select mang \u0111\u1ebfn hai l\u1ef1a ch\u1ecdn l\u00e0 tr\u00edch xu\u1ea5t to\u00e0n b\u1ed9 b\u1ea3ng ho\u1eb7c ch\u1ecdn c\u1ed9t mu\u1ed1n thao t\u00e1c.<\/p>\n<p style=\"text-align: justify;\">C\u00fa ph\u00e1p c\u00e2u l\u1ec7nh Select nh\u01b0 sau:<\/p>\n<ul style=\"text-align: justify;\">\n<li style=\"font-weight: 400;\" aria-level=\"1\">Ch\u1ec9 ch\u1ecdn m\u1ed9t c\u1ed9t c\u00f3 gi\u00e1 tr\u1ecb mu\u1ed1n l\u1ea5y<\/li>\n<\/ul>\n<p style=\"text-align: justify;\">SELECT cot1, cot2, cotN FROM ten_bang;<\/p>\n<ul style=\"text-align: justify;\">\n<li style=\"font-weight: 400;\" aria-level=\"1\">Ch\u1ecdn gi\u00e1 tr\u1ecb c\u1ee7a t\u1ea5t c\u1ea3 c\u00e1c c\u1ed9t trong b\u1ea3ng<\/li>\n<\/ul>\n<p style=\"text-align: justify;\">SELECT * FROM ten_bang;<\/p>\n<figure id=\"attachment_8185\" aria-describedby=\"caption-attachment-8185\" style=\"width: 650px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-8185\" src=\"https:\/\/teky.edu.vn\/blog\/wp-content\/uploads\/2021\/07\/hoc-sql-co-ban-dem-den-nhieu-loi-ich.jpg\" alt=\"H\u1ecdc SQL c\u01a1 b\u1ea3n \u0111em \u0111\u1ebfn nhi\u1ec1u l\u1ee3i \u00edch\" width=\"650\" height=\"400\" srcset=\"https:\/\/teky.edu.vn\/blog\/wp-content\/uploads\/2021\/07\/hoc-sql-co-ban-dem-den-nhieu-loi-ich.jpg 650w, https:\/\/teky.edu.vn\/blog\/wp-content\/uploads\/2021\/07\/hoc-sql-co-ban-dem-den-nhieu-loi-ich-400x246.jpg 400w\" sizes=\"auto, (max-width: 650px) 100vw, 650px\" \/><figcaption id=\"caption-attachment-8185\" class=\"wp-caption-text\">H\u1ecdc SQL c\u01a1 b\u1ea3n \u0111em \u0111\u1ebfn nhi\u1ec1u l\u1ee3i \u00edch<\/figcaption><\/figure>\n<h3 style=\"text-align: justify;\"><span class=\"ez-toc-section\" id=\"Menh_de_Distinct\"><\/span>M\u1ec7nh \u0111\u1ec1 Distinct<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p style=\"text-align: justify;\">Khi nh\u1eafc \u0111\u1ebfn c\u00e1c c\u00e2u l\u1ec7nh SQL c\u01a1 b\u1ea3n th\u00ec kh\u00f4ng th\u1ec3 n\u00e0o thi\u1ebfu \u0111\u01b0\u1ee3c t\u1eeb kh\u00f3a Distinct. M\u1ec7nh \u0111\u1ec1 Distinct \u0111\u01b0\u1ee3c d\u00f9ng \u0111\u1ec3 k\u1ebft h\u1ee3p v\u1edbi truy v\u1ea5n Select trong tr\u01b0\u1eddng h\u1ee3p ng\u01b0\u1eddi d\u00f9ng mu\u1ed1n lo\u1ea1i c\u00e1c b\u1ea3n ghi b\u1ecb tr\u00f9ng l\u1eb7p.<\/p>\n<p style=\"text-align: justify;\">C\u00fa ph\u00e1p m\u1ec7nh \u0111\u1ec1 nh\u01b0 sau:<\/p>\n<p style=\"text-align: justify;\">SELECT DISTINCT cot1, cot2,&#8230;..cotN<\/p>\n<p style=\"text-align: justify;\">FROM ten_bang<\/p>\n<p style=\"text-align: justify;\">WHERE [dieu_kien]<\/p>\n<p><em><strong>M\u1eddi b\u1ea1n \u0111\u1ecdc tham kh\u1ea3o th\u00eam<\/strong>: <span style=\"color: #0000ff;\"><a style=\"color: #0000ff;\" href=\"https:\/\/teky.edu.vn\/blog\/thread-trong-java\/\">Thread trong Java l\u00e0 g\u00ec?<\/a><\/span><\/em><\/p>\n<p style=\"text-align: justify;\">V\u1eeba r\u1ed3i Teky \u0111\u00e3 \u0111i\u1ec3m nhanh qua c\u00e1c kh\u00e1i ni\u1ec7m c\u01a1 b\u1ea3n c\u1ee7a SQL v\u00e0 gi\u1edbi thi\u1ec7u \u0111\u1ebfn b\u1ea1n \u0111\u1ecdc m\u1ed9t s\u1ed1 c\u00e2u l\u1ec7nh SQL \u0111\u01a1n gi\u1ea3n d\u1ec5 s\u1eed d\u1ee5ng. C\u00e1c c\u00e2u l\u1ec7nh truy v\u1ea5n trong SQL \u0111\u00f3ng vai tr\u00f2 r\u1ea5t quan tr\u1ecdng trong c\u00e1c ho\u1ea1t \u0111\u1ed9ng v\u1edbi c\u01a1 s\u1edf d\u1eef li\u1ec7u. V\u00ec th\u1ebf mong b\u1ea1n \u0111\u1ecdc nhanh ch\u00f3ng h\u1ecdc h\u1ecfi \u0111\u01b0\u1ee3c th\u00eam nhi\u1ec1u ki\u1ebfn th\u1ee9c b\u1ed5 \u00edch trong l\u0129nh v\u1ef1c n\u00e0y nh\u00e9!<\/p>\n<h2><span class=\"ez-toc-section\" id=\"Thong_tin_co_ban_ve_Hoc_vien_chuyen_dao_tao_cong_nghe_va_lap_trinh_%E2%80%93_Teky\"><\/span><span style=\"font-size: 24px; color: #339966;\" data-sheets-value=\"{&quot;1&quot;:2,&quot;2&quot;:&quot;C\u00f9ng T\u00ecm Hi\u1ec3u V\u1ec1 Teky H\u1ecdc Vi\u1ec7n 5 sao \u0110\u00e0o T\u1ea1o Tr\u1ebb Em H\u1ecdc L\u1eadp Tr\u00ecnh (4-18 tu\u1ed5i)&quot;}\" data-sheets-userformat=\"{&quot;2&quot;:17153,&quot;3&quot;:{&quot;1&quot;:0},&quot;11&quot;:4,&quot;12&quot;:0,&quot;17&quot;:1}\">Th\u00f4ng tin c\u01a1 b\u1ea3n v\u1ec1 H\u1ecdc vi\u1ec7n chuy\u00ean \u0111\u00e0o t\u1ea1o c\u00f4ng ngh\u1ec7 v\u00e0 l\u1eadp tr\u00ecnh &#8211; Teky\u00a0<\/span><span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p><iframe loading=\"lazy\" title=\"H\u1ecdc l\u1eadp tr\u00ecnh tr\u1ebb em \u1edf \u0111\u00e2u? - Gi\u1edbi thi\u1ec7u h\u1ecdc vi\u1ec7n c\u00f4ng ngh\u1ec7 TEKY h\u00e0ng \u0111\u1ea7u Vi\u1ec7t Nam\" width=\"500\" height=\"281\" src=\"https:\/\/www.youtube.com\/embed\/kGgr0XJAxFM?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe><\/p>\n<p><strong>TEKY l\u00e0 H\u1ecdc vi\u1ec7n s\u00e1ng t\u1ea1o c\u00f4ng ngh\u1ec7<\/strong> v\u1edbi ch\u01b0\u01a1ng tr\u00ecnh gi\u1ea3ng d\u1ea1y STEAM (Science \u2013 Technology \u2013 Engineering \u2013 Art \u2013 Mathematics) theo chu\u1ea9n M\u1ef9 \u0111\u1ea7u ti\u00ean t\u1ea1i Vi\u1ec7t Nam d\u00e0nh cho tr\u1ebb em t\u1eeb 4 \u0111\u1ebfn 18 tu\u1ed5i.<\/p>\n<p>\u0110\u01b0\u1ee3c th\u00e0nh l\u1eadp v\u00e0o th\u00e1ng 6 n\u0103m 2016, TEKY quy\u1ebft t\u00e2m th\u1ef1c hi\u1ec7n s\u1ee9 m\u1ec7nh mang \u0111\u1ebfn cho th\u1ebf h\u1ec7 tr\u1ebb Vi\u1ec7t Nam ki\u1ebfn th\u1ee9c to\u00e0n di\u1ec7n v\u1ec1 STEAM, \u0111\u1eb7c bi\u1ec7t l\u00e0 c\u00e1c t\u01b0 duy c\u00f4ng ngh\u1ec7, khoa h\u1ecdc m\u00e1y t\u00ednh v\u00e0 k\u1ef9 n\u0103ng th\u1ebf k\u1ef7 21 \u2013 4Cs (Critical Thinking: T\u01b0 duy ph\u1ea3n bi\u1ec7n \u2013 Communication: Giao ti\u1ebfp \u2013 Creativity: S\u00e1ng t\u1ea1o \u2013 Collaboration: L\u00e0m vi\u1ec7c nh\u00f3m).<\/p>\n<h4><span class=\"ez-toc-section\" id=\"Day_la_chuong_trinh_khong_chi_trang_bi_kien_thuc_lap_trinh_ma_con_ren_luyen_nhom_ky_nang_4Cs_Tre_se_duoc\"><\/span>\u0110\u00e2y l\u00e0 ch\u01b0\u01a1ng tr\u00ecnh kh\u00f4ng ch\u1ec9 trang b\u1ecb ki\u1ebfn th\u1ee9c l\u1eadp tr\u00ecnh m\u00e0 c\u00f2n r\u00e8n luy\u1ec7n nh\u00f3m k\u1ef9 n\u0103ng 4Cs. Tr\u1ebb s\u1ebd \u0111\u01b0\u1ee3c:<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<ul>\n<li>\u00a0H\u1ecdc t\u01b0 duy ph\u1ea3n bi\u1ec7n th\u00f4ng qua vi\u1ec7c ph\u00e2n t\u00edch c\u00e1c v\u1ea5n \u0111\u1ec1.<\/li>\n<li>\u00a0H\u1ecdc t\u00ednh s\u00e1ng t\u1ea1o t\u01b0 duy Logic th\u00f4ng qua vi\u1ec7c l\u1eafp \u0111\u1eb7t v\u00e0 l\u1eadp tr\u00ecnh robot th \u00f4ng qua c\u00e1c m\u00f4 h\u00ecnh Lego Mindstorm, app tr\u00f2 ch\u01a1i. Gi\u00fap con h\u1ecdc gi\u1ecfi m\u00f4n To\u00e1n tr\u00ean l\u1edbp<\/li>\n<li>\u00a0K\u1ef9 n\u0103ng h\u1ee3p t\u00e1c th\u00f4ng qua c\u00e1c tr\u00f2 ch\u01a1i team-building, c\u00e1c d\u1ef1 \u00e1n nh\u00f3m tr\u00ean l\u1edbp.<\/li>\n<li>\u00a0Ph\u00e1t huy kh\u1ea3 n\u0103ng giao ti\u1ebfp hi\u1ec7u qu\u1ea3 b\u1eb1ng nhi\u1ec1u b\u00e0i t\u1eadp v\u00e0 ho\u1ea1t \u0111\u1ed9ng h\u1ea5p d\u1eabn.<\/li>\n<\/ul>\n<p><iframe loading=\"lazy\" title=\"Shark Nguy\u1ec5n Ho\u00e0 B\u00ecnh \u0111\u1ed3ng h\u00e0nh c\u00f9ng con h\u1ecdc l\u1eadp tr\u00ecnh t\u1ea1i h\u1ecdc vi\u1ec7n c\u00f4ng ngh\u1ec7 Teky h\u00e0ng \u0111\u1ea7u Vi\u1ec7t Nam\" width=\"500\" height=\"281\" src=\"https:\/\/www.youtube.com\/embed\/q6QbqIs6ll8?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe><\/p>\n<p>C\u00e1c b\u1ed9 m\u00f4n gi\u1ea3ng d\u1ea1y t\u1ea1i Teky g\u1ed3m: <span style=\"font-weight: 400;\">L\u1eadp tr\u00ecnh v\u00e0 ph\u00e1t tri\u1ec3n \u1ee9ng d\u1ee5ng<\/span><span style=\"font-weight: 400;\">, <\/span><span style=\"font-weight: 400;\">l\u1eadp tr\u00ecnh game<\/span><span style=\"font-weight: 400;\">, <\/span><span style=\"font-weight: 400;\">l\u1eadp tr\u00ecnh web v\u1edbi python<\/span> <span style=\"font-weight: 400;\">\u00a0<\/span><span style=\"font-weight: 400;\">L\u1eadp tr\u00ecnh Scratch<\/span> <span style=\"font-weight: 400;\">Robotics<\/span> Engineering, C\u00f4ng ngh\u1ec7 3D v\u00e0 MultiMedia. Ch\u00fang t\u00f4i tin r\u1eb1ng tr\u1ebb em Vi\u1ec7t Nam c\u00f3 c\u01a1 h\u1ed9i ph\u00e1t tri\u1ec3n m\u1ea1nh m\u1ebd trong m\u1ed9t n\u1ec1n kinh t\u1ebf s\u1ed1 v\u00e0 c\u1ea7n \u0111\u01b0\u1ee3c trang b\u1ecb s\u1eb5n s\u00e0ng \u0111\u1ec3 tr\u1edf th\u00e0nh nh\u1eefng doanh nh\u00e2n c\u00f4ng ngh\u1ec7 trong t\u01b0\u01a1ng lai.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Ng\u00f4n ng\u1eef l\u1eadp tr\u00ecnh l\u00e0 l\u0129nh v\u1ef1c kh\u00f4ng th\u1ec3 b\u1ecf qua khi l\u00e0m vi\u1ec7c trong ng\u00e0nh IT. C\u00f3 r\u1ea5t nhi\u1ec1u lo\u1ea1i ng\u00f4n ng\u1eef l\u1eadp tr\u00ecnh kh\u00e1c nhau. Vi\u1ec7c b\u1ea3n ph\u1ea3i h\u1ecdc lo\u1ea1i n\u00e0o l\u00e0 t\u00f9y theo y\u00eau c\u1ea7u c\u1ee7a c\u00f4ng vi\u1ec7c. N\u1ebfu hay ph\u1ea3i l\u00e0m vi\u1ec7c c\u00f9ng c\u01a1 s\u1edf d\u1eef li\u1ec7u, ch\u1eafc h\u1eb3n b\u1ea1n \u0111\u1ecdc &hellip;<\/p>\n","protected":false},"author":10,"featured_media":25160,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[28],"tags":[299,260],"class_list":["post-8183","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-lap-trinh","tag-hoc-lap-trinh-online-cho-tre-em","tag-teky-edtech"],"yoast_head":"<!-- This site is optimized with the Yoast SEO Premium plugin v20.9 (Yoast SEO v26.0) - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>Kh\u00e1m ph\u00e1 SQL: Ng\u00f4n ng\u1eef l\u1eadp tr\u00ecnh quan tr\u1ecdng cho c\u00f4ng vi\u1ec7c v\u1edbi c\u01a1 s\u1edf d\u1eef li\u1ec7u<\/title>\n<meta name=\"description\" content=\"B\u1ea1n c\u00f3 bi\u1ebft r\u1eb1ng c\u00e2u l\u1ec7nh SQL mang \u0111\u1ebfn r\u1ea5t nhi\u1ec1u l\u1ee3i \u00edch cho c\u00f4ng vi\u1ec7c l\u1eadp tr\u00ecnh. 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