{"id":8809,"date":"2025-03-07T16:34:48","date_gmt":"2025-03-07T09:34:48","guid":{"rendered":"https:\/\/mb668s.com\/cam-nang-7mb66-xoc-dia\/?p=8809"},"modified":"2026-03-27T17:21:33","modified_gmt":"2026-03-27T10:21:33","slug":"sql-la-gi","status":"publish","type":"post","link":"https:\/\/mb668s.com\/cam-nang-7mb66-xoc-dia\/tu-van-nghe-nghiep\/sql-la-gi","title":{"rendered":"SQL l\u00e0 g\u00ec? Nh\u1eefng \u0111i\u1ec1u c\u1ea7n bi\u1ebft v\u00ea\u0300 c\u01a1 s\u1edf d\u1eef li\u1ec7u"},"content":{"rendered":"\n

C\u01a1 s\u1edf d\u1eef li\u1ec7u l\u00e0 m\u1ed9t ph\u1ea7n quan tr\u1ecdng trong c\u00f4ng ngh\u1ec7 th\u00f4ng tin, gi\u00fap l\u01b0u tr\u1eef v\u00e0 qu\u1ea3n l\u00fd d\u1eef li\u1ec7u m\u1ed9t c\u00e1ch hi\u1ec7u qu\u1ea3. D\u00f9 hi\u1ec7n nay c\u00f3 nhi\u1ec1u c\u00f4ng c\u1ee5 m\u1edbi ra \u0111\u1eddi, nh\u01b0ng SQL v\u1eabn gi\u1eef vai tr\u00f2 c\u1ed1t l\u00f5i trong vi\u1ec7c truy v\u1ea5n v\u00e0 qu\u1ea3n l\u00fd d\u1eef li\u1ec7u trong c\u00e1c h\u1ec7 th\u1ed1ng ph\u1ea7n m\u1ec1m. V\u1eady SQL l\u00e0 g\u00ec<\/strong>? H\u00e3y c\u00f9ng kh\u00e1m ph\u00e1 t\u1ea5t t\u1ea7n t\u1eadt v\u1ec1 SQL trong b\u00e0i vi\u1ebft d\u01b0\u1edbi \u0111\u00e2y nh\u00e9!<\/p>\n\n\n\n

\"SQL<\/figure>\n\n\n\n

SQL l\u00e0 g\u00ec?<\/h2>\n\n\n\n
\n

SQL (Structured Query Language) l\u00e0 ng\u00f4n ng\u1eef truy v\u1ea5n c\u00f3 c\u1ea5u tr\u00fac, \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng \u0111\u1ec3 qu\u1ea3n l\u00fd v\u00e0 thao t\u00e1c d\u1eef li\u1ec7u trong c\u00e1c h\u1ec7 qu\u1ea3n tr\u1ecb c\u01a1 s\u1edf d\u1eef li\u1ec7u quan h\u1ec7 (RDBMS).<\/strong><\/p>\n<\/blockquote>\n\n\n\n

SQL cho ph\u00e9p ng\u01b0\u1eddi d\u00f9ng truy v\u1ea5n, ch\u00e8n, c\u1eadp nh\u1eadt, x\u00f3a d\u1eef li\u1ec7u c\u0169ng nh\u01b0 qu\u1ea3n l\u00fd c\u1ea5u tr\u00fac c\u1ee7a c\u01a1 s\u1edf d\u1eef li\u1ec7u. V\u1edbi c\u00fa ph\u00e1p \u0111\u01a1n gi\u1ea3n, d\u1ec5 h\u1ecdc nh\u01b0ng m\u1ea1nh m\u1ebd, SQL l\u00e0 c\u00f4ng c\u1ee5 quan tr\u1ecdng trong ph\u00e1t tri\u1ec3n ph\u1ea7n m\u1ec1m, ph\u00e2n t\u00edch d\u1eef li\u1ec7u v\u00e0 qu\u1ea3n tr\u1ecb h\u1ec7 th\u1ed1ng.<\/p>\n\n\n\n

L\u1ecbch s\u1eed v\u00e0 qu\u00e1 tr\u00ecnh ph\u00e1t tri\u1ec3n SQL<\/h2>\n\n\n\n

SQL (Structured Query Language) \u0111\u01b0\u1ee3c ph\u00e1t tri\u1ec3n t\u1eeb nh\u1eefng n\u0103m 1970 b\u1edfi IBM, d\u1ef1a tr\u00ean m\u00f4 h\u00ecnh c\u01a1 s\u1edf d\u1eef li\u1ec7u quan h\u1ec7 c\u1ee7a Edgar F. Codd. Ban \u0111\u1ea7u c\u00f3 t\u00ean SEQUEL, SQL nhanh ch\u00f3ng tr\u1edf th\u00e0nh ti\u00eau chu\u1ea9n qu\u1ed1c t\u1ebf v\u00e0o n\u0103m 1986 (ANSI) v\u00e0 1987 (ISO). C\u00e1c h\u1ec7 qu\u1ea3n tr\u1ecb CSDL l\u1edbn nh\u01b0 Oracle, MySQL, SQL Server, PostgreSQL l\u1ea7n l\u01b0\u1ee3t ra \u0111\u1eddi, gi\u00fap SQL tr\u1edf th\u00e0nh c\u00f4ng c\u1ee5 qu\u1ea3n l\u00fd d\u1eef li\u1ec7u ph\u1ed5 bi\u1ebfn nh\u1ea5t hi\u1ec7n nay.<\/p>\n\n\n\n

Vai tr\u00f2 quan tr\u1ecdng c\u1ee7a SQL trong qu\u1ea3n l\u00fd v\u00e0 thao t\u00e1c d\u1eef li\u1ec7u<\/h2>\n\n\n\n

SQL \u0111\u00f3ng vai tr\u00f2 c\u1ed1t l\u00f5i trong vi\u1ec7c qu\u1ea3n l\u00fd, x\u1eed l\u00fd v\u00e0 thao t\u00e1c d\u1eef li\u1ec7u trong c\u00e1c h\u1ec7 th\u1ed1ng th\u00f4ng tin hi\u1ec7n \u0111\u1ea1i. T\u1eeb vi\u1ec7c t\u1ea1o l\u1eadp c\u01a1 s\u1edf d\u1eef li\u1ec7u, truy xu\u1ea5t th\u00f4ng tin nhanh ch\u00f3ng, \u0111\u1ebfn ki\u1ec3m so\u00e1t truy c\u1eadp v\u00e0 t\u00edch h\u1ee3p v\u1edbi c\u00e1c \u1ee9ng d\u1ee5ng ph\u1ea7n m\u1ec1m, SQL gi\u00fap \u0111\u1ea3m b\u1ea3o hi\u1ec7u su\u1ea5t v\u00e0 t\u00ednh to\u00e0n v\u1eb9n c\u1ee7a d\u1eef li\u1ec7u trong m\u1ecdi l\u0129nh v\u1ef1c.<\/p>\n\n\n\n

    \n
  • T\u1ea1o v\u00e0 qu\u1ea3n l\u00fd d\u1eef li\u1ec7u:<\/strong> SQL gi\u00fap ng\u01b0\u1eddi d\u00f9ng t\u1ea1o b\u1ea3ng, nh\u1eadp d\u1eef li\u1ec7u, v\u00e0 c\u1eadp nh\u1eadt d\u1eef li\u1ec7u d\u1ec5 d\u00e0ng.<\/li>\n\n\n\n
  • Truy v\u1ea5n d\u1eef li\u1ec7u:<\/strong> Ng\u01b0\u1eddi d\u00f9ng c\u00f3 th\u1ec3 t\u00ecm ki\u1ebfm, t\u1ed5ng h\u1ee3p, v\u00e0 ph\u00e2n t\u00edch d\u1eef li\u1ec7u nhanh ch\u00f3ng v\u1edbi c\u00e1c c\u00e2u l\u1ec7nh SQL.<\/li>\n\n\n\n
  • Ki\u1ec3m so\u00e1t truy c\u1eadp:<\/strong> SQL cung c\u1ea5p c\u00e1c c\u01a1 ch\u1ebf b\u1ea3o m\u1eadt nh\u01b0 ph\u00e2n quy\u1ec1n truy c\u1eadp, m\u00e3 h\u00f3a d\u1eef li\u1ec7u.<\/li>\n\n\n\n
  • T\u00edch h\u1ee3p v\u1edbi \u1ee9ng d\u1ee5ng:<\/strong> SQL \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng trong nhi\u1ec1u h\u1ec7 th\u1ed1ng ph\u1ea7n m\u1ec1m, gi\u00fap k\u1ebft n\u1ed1i v\u00e0 t\u01b0\u01a1ng t\u00e1c v\u1edbi d\u1eef li\u1ec7u.<\/li>\n<\/ul>\n\n\n\n

    C\u00e1ch SQL hoa\u0323t \u0111\u00f4\u0323ng trong c\u01a1 s\u1edf d\u1eef li\u1ec7u<\/h2>\n\n\n\n

    SQL \u0111\u00f3ng vai tr\u00f2 trung gian gi\u1eefa ng\u01b0\u1eddi d\u00f9ng v\u00e0 h\u1ec7 qu\u1ea3n tr\u1ecb c\u01a1 s\u1edf d\u1eef li\u1ec7u quan h\u1ec7 (RDBMS), gi\u00fap truy v\u1ea5n, qu\u1ea3n l\u00fd v\u00e0 thao t\u00e1c d\u1eef li\u1ec7u m\u1ed9t c\u00e1ch hi\u1ec7u qu\u1ea3. Khi m\u1ed9t l\u1ec7nh SQL \u0111\u01b0\u1ee3c th\u1ef1c thi, h\u1ec7 th\u1ed1ng s\u1ebd x\u1eed l\u00fd truy v\u1ea5n, t\u1ed1i \u01b0u h\u00f3a v\u00e0 tr\u1ea3 v\u1ec1 k\u1ebft qu\u1ea3 t\u01b0\u01a1ng \u1ee9ng.<\/p>\n\n\n\n

    SQL v\u1eadn h\u00e0nh nh\u01b0 th\u1ebf n\u00e0o?<\/h3>\n\n\n\n

    SQL ho\u1ea1t \u0111\u1ed9ng theo m\u00f4 h\u00ecnh client-server, trong \u0111\u00f3:<\/p>\n\n\n\n

      \n
    • Ng\u01b0\u1eddi d\u00f9ng g\u1eedi truy v\u1ea5n SQL t\u1eeb \u1ee9ng d\u1ee5ng ho\u1eb7c giao di\u1ec7n d\u00f2ng l\u1ec7nh.<\/li>\n\n\n\n
    • M\u00e1y ch\u1ee7 c\u01a1 s\u1edf d\u1eef li\u1ec7u nh\u1eadn truy v\u1ea5n, x\u1eed l\u00fd v\u00e0 tr\u1ea3 k\u1ebft qu\u1ea3 v\u1ec1 cho client.<\/li>\n\n\n\n
    • H\u1ec7 th\u1ed1ng c\u01a1 s\u1edf d\u1eef li\u1ec7u c\u00f3 th\u1ec3 t\u1ed1i \u01b0u h\u00f3a truy v\u1ea5n \u0111\u1ec3 t\u0103ng hi\u1ec7u su\u1ea5t x\u1eed l\u00fd d\u1eef li\u1ec7u.<\/li>\n<\/ul>\n\n\n\n

      Qu\u00e1 tr\u00ecnh truy v\u1ea5n d\u1eef li\u1ec7u v\u1edbi SQL<\/h3>\n\n\n\n
        \n
      • Ng\u01b0\u1eddi d\u00f9ng nh\u1eadp truy v\u1ea5n SQL<\/strong> (v\u00ed d\u1ee5: SELECT * FROM users;).<\/li>\n\n\n\n
      • H\u1ec7 th\u1ed1ng c\u01a1 s\u1edf d\u1eef li\u1ec7u ph\u00e2n t\u00edch truy v\u1ea5n<\/strong> v\u00e0 t\u1ed1i \u01b0u h\u00f3a.<\/li>\n\n\n\n
      • M\u00e1y ch\u1ee7 th\u1ef1c thi truy v\u1ea5n<\/strong> v\u00e0 truy xu\u1ea5t d\u1eef li\u1ec7u t\u1eeb b\u1ea3ng t\u01b0\u01a1ng \u1ee9ng.<\/li>\n\n\n\n
      • D\u1eef li\u1ec7u \u0111\u01b0\u1ee3c tr\u1ea3 v\u1ec1<\/strong> d\u01b0\u1edbi d\u1ea1ng b\u1ea3ng k\u1ebft qu\u1ea3.<\/li>\n<\/ul>\n\n\n\n

        Ki\u1ebfn tr\u00fac v\u00e0 m\u00f4 h\u00ecnh c\u1ee7a m\u1ed9t h\u1ec7 th\u1ed1ng c\u01a1 s\u1edf d\u1eef li\u1ec7u s\u1eed d\u1ee5ng SQL<\/h3>\n\n\n\n

        M\u1ed9t h\u1ec7 th\u1ed1ng c\u01a1 s\u1edf d\u1eef li\u1ec7u quan h\u1ec7 th\u01b0\u1eddng c\u00f3 c\u00e1c th\u00e0nh ph\u1ea7n ch\u00ednh:<\/p>\n\n\n\n

          \n
        • M\u00e1y ch\u1ee7 c\u01a1 s\u1edf d\u1eef li\u1ec7u:<\/strong> Ch\u1ee9a v\u00e0 qu\u1ea3n l\u00fd d\u1eef li\u1ec7u, x\u1eed l\u00fd truy v\u1ea5n SQL.<\/li>\n\n\n\n
        • Ng\u01b0\u1eddi d\u00f9ng ho\u1eb7c \u1ee9ng d\u1ee5ng client:<\/strong> G\u1eedi truy v\u1ea5n SQL v\u00e0 nh\u1eadn k\u1ebft qu\u1ea3.<\/li>\n\n\n\n
        • Giao th\u1ee9c k\u1ebft n\u1ed1i:<\/strong> Giao ti\u1ebfp gi\u1eefa \u1ee9ng d\u1ee5ng v\u00e0 m\u00e1y ch\u1ee7 th\u00f4ng qua giao th\u1ee9c nh\u01b0 JDBC, ODBC.<\/li>\n\n\n\n
        • C\u00f4ng c\u1ee5 t\u1ed1i \u01b0u h\u00f3a:<\/strong> Gi\u00fap c\u1ea3i thi\u1ec7n hi\u1ec7u su\u1ea5t truy v\u1ea5n d\u1eef li\u1ec7u.<\/li>\n<\/ul>\n\n\n\n

          C\u00e1c th\u00e0nh ph\u1ea7n quan tr\u1ecdng c\u1ee7a SQL<\/h2>\n\n\n\n

          SQL bao g\u1ed3m nhi\u1ec1u nh\u00f3m c\u00e2u l\u1ec7nh kh\u00e1c nhau, m\u1ed7i nh\u00f3m ph\u1ee5c v\u1ee5 m\u1ed9t m\u1ee5c \u0111\u00edch ri\u00eang trong qu\u1ea3n l\u00fd v\u00e0 thao t\u00e1c d\u1eef li\u1ec7u.<\/p>\n\n\n\n

          Ng\u00f4n ng\u1eef \u0111\u1ecbnh ngh\u0129a d\u1eef li\u1ec7u (DDL – Data Definition Language)<\/strong><\/p>\n\n\n\n

          DDL l\u00e0 t\u1eadp h\u1ee3p c\u00e1c c\u00e2u l\u1ec7nh gi\u00fap t\u1ea1o v\u00e0 qu\u1ea3n l\u00fd c\u1ea5u tr\u00fac c\u1ee7a c\u01a1 s\u1edf d\u1eef li\u1ec7u, bao g\u1ed3m:<\/p>\n\n\n\n

            \n
          • CREATE<\/strong>: T\u1ea1o b\u1ea3ng, c\u01a1 s\u1edf d\u1eef li\u1ec7u, ho\u1eb7c c\u00e1c \u0111\u1ed1i t\u01b0\u1ee3ng kh\u00e1c.\n
              \n
            • V\u00ed d\u1ee5:<\/em> CREATE TABLE users (id INT PRIMARY KEY, name VARCHAR(50));<\/li>\n<\/ul>\n<\/li>\n\n\n\n
            • ALTER<\/strong>: S\u1eeda \u0111\u1ed5i c\u1ea5u tr\u00fac c\u1ee7a b\u1ea3ng ho\u1eb7c c\u01a1 s\u1edf d\u1eef li\u1ec7u.\n
                \n
              • V\u00ed d\u1ee5:<\/em> ALTER TABLE users ADD email VARCHAR(100);<\/li>\n<\/ul>\n<\/li>\n\n\n\n
              • DROP<\/strong>: X\u00f3a ho\u00e0n to\u00e0n m\u1ed9t b\u1ea3ng ho\u1eb7c c\u01a1 s\u1edf d\u1eef li\u1ec7u.\n
                  \n
                • V\u00ed d\u1ee5:<\/em> DROP TABLE users;<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n\n

                  Ng\u00f4n ng\u1eef x\u1eed l\u00fd d\u1eef li\u1ec7u (DML – Data Manipulation Language)<\/strong><\/p>\n\n\n\n

                  DML gi\u00fap thao t\u00e1c d\u1eef li\u1ec7u b\u00ean trong b\u1ea3ng:<\/p>\n\n\n\n

                    \n
                  • SELECT<\/strong>: Truy v\u1ea5n d\u1eef li\u1ec7u t\u1eeb b\u1ea3ng.\n
                      \n
                    • V\u00ed d\u1ee5:<\/em> SELECT * FROM users;<\/li>\n<\/ul>\n<\/li>\n\n\n\n
                    • INSERT<\/strong>: Th\u00eam d\u1eef li\u1ec7u v\u00e0o b\u1ea3ng.\n
                        \n
                      • V\u00ed d\u1ee5:<\/em> INSERT INTO users (id, name) VALUES (1, ‘Nguyen Van A’);<\/li>\n<\/ul>\n<\/li>\n\n\n\n
                      • UPDATE<\/strong>: C\u1eadp nh\u1eadt d\u1eef li\u1ec7u trong b\u1ea3ng.\n
                          \n
                        • V\u00ed d\u1ee5:<\/em> UPDATE users SET name = ‘Tran Van B’ WHERE id = 1;<\/li>\n<\/ul>\n<\/li>\n\n\n\n
                        • DELETE<\/strong>: X\u00f3a d\u1eef li\u1ec7u kh\u1ecfi b\u1ea3ng.\n
                            \n
                          • V\u00ed d\u1ee5:<\/em> DELETE FROM users WHERE id = 1;<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n\n

                            Ng\u00f4n ng\u1eef ki\u1ec3m so\u00e1t d\u1eef li\u1ec7u (DCL – Data Control Language)<\/strong><\/p>\n\n\n\n

                            DCL li\u00ean quan \u0111\u1ebfn quy\u1ec1n truy c\u1eadp v\u00e0 b\u1ea3o m\u1eadt d\u1eef li\u1ec7u:<\/p>\n\n\n\n

                              \n
                            • GRANT<\/strong>: C\u1ea5p quy\u1ec1n truy c\u1eadp cho ng\u01b0\u1eddi d\u00f9ng.\n
                                \n
                              • V\u00ed d\u1ee5:<\/em> GRANT SELECT ON users TO admin;<\/li>\n<\/ul>\n<\/li>\n\n\n\n
                              • REVOKE<\/strong>: Thu h\u1ed3i quy\u1ec1n truy c\u1eadp t\u1eeb ng\u01b0\u1eddi d\u00f9ng.\n
                                  \n
                                • V\u00ed d\u1ee5:<\/em> REVOKE SELECT ON users FROM admin;<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n\n

                                  Ng\u00f4n ng\u1eef ki\u1ec3m so\u00e1t giao d\u1ecbch (TCL – Transaction Control Language)<\/strong><\/p>\n\n\n\n

                                  TCL h\u1ed7 tr\u1ee3 ki\u1ec3m so\u00e1t c\u00e1c giao d\u1ecbch d\u1eef li\u1ec7u, \u0111\u1ea3m b\u1ea3o t\u00ednh to\u00e0n v\u1eb9n v\u00e0 nh\u1ea5t qu\u00e1n:<\/p>\n\n\n\n

                                    \n
                                  • COMMIT<\/strong>: L\u01b0u thay \u0111\u1ed5i v\u0129nh vi\u1ec5n v\u00e0o c\u01a1 s\u1edf d\u1eef li\u1ec7u.\n
                                      \n
                                    • V\u00ed d\u1ee5:<\/em> COMMIT;<\/li>\n<\/ul>\n<\/li>\n\n\n\n
                                    • ROLLBACK<\/strong>: Ho\u00e0n t\u00e1c c\u00e1c thay \u0111\u1ed5i ch\u01b0a \u0111\u01b0\u1ee3c x\u00e1c nh\u1eadn.\n
                                        \n
                                      • V\u00ed d\u1ee5:<\/em> ROLLBACK;<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n\n

                                        C\u00fa ph\u00e1p v\u00e0 c\u00e2u l\u1ec7nh c\u01a1 b\u1ea3n c\u1ee7a SQL<\/h2>\n\n\n\n

                                        C\u00e1ch vi\u1ebft m\u1ed9t c\u00e2u l\u1ec7nh SQL c\u01a1 b\u1ea3n<\/strong><\/p>\n\n\n\n

                                        M\u1ecdi c\u00e2u l\u1ec7nh SQL \u0111\u1ec1u tu\u00e2n theo c\u00fa ph\u00e1p chu\u1ea9n:<\/p>\n\n\n\n

                                        sql<\/p>\n\n\n\n

                                        CopyEdit<\/p>\n\n\n\n

                                        SELECT <column_names> FROM <table_name> WHERE <condition>;<\/p>\n\n\n\n

                                        V\u00ed d\u1ee5:<\/p>\n\n\n\n

                                        sql<\/p>\n\n\n\n

                                        CopyEdit<\/p>\n\n\n\n

                                        SELECT name, email FROM users WHERE id = 1;<\/p>\n\n\n\n

                                        C\u00e2u l\u1ec7nh SELECT \u2013 Truy v\u1ea5n d\u1eef li\u1ec7u<\/strong><\/p>\n\n\n\n

                                        C\u00e2u l\u1ec7nh SELECT gi\u00fap l\u1ea5y d\u1eef li\u1ec7u t\u1eeb b\u1ea3ng:<\/p>\n\n\n\n

                                          \n
                                        • Ch\u1ecdn t\u1ea5t c\u1ea3 c\u00e1c c\u1ed9t:<\/li>\n<\/ul>\n\n\n\n

                                          sql<\/p>\n\n\n\n

                                          CopyEdit<\/p>\n\n\n\n

                                          SELECT * FROM users;<\/p>\n\n\n\n

                                            \n
                                          • Ch\u1ecdn c\u1ed9t c\u1ee5 th\u1ec3:<\/li>\n<\/ul>\n\n\n\n

                                            sql<\/p>\n\n\n\n

                                            CopyEdit<\/p>\n\n\n\n

                                            SELECT name, email FROM users;<\/p>\n\n\n\n

                                              \n
                                            • L\u1ecdc d\u1eef li\u1ec7u v\u1edbi WHERE:<\/li>\n<\/ul>\n\n\n\n

                                              sql<\/p>\n\n\n\n

                                              CopyEdit<\/p>\n\n\n\n

                                              SELECT * FROM users WHERE name = ‘Nguyen Van A’;<\/p>\n\n\n\n

                                              C\u00e2u l\u1ec7nh INSERT, UPDATE, DELETE \u2013 Thao t\u00e1c d\u1eef li\u1ec7u<\/strong><\/p>\n\n\n\n

                                                \n
                                              • INSERT<\/strong>:<\/li>\n<\/ul>\n\n\n\n

                                                sql<\/p>\n\n\n\n

                                                CopyEdit<\/p>\n\n\n\n

                                                INSERT INTO users (id, name, email) VALUES (1, ‘Nguyen Van A’, ‘a@example.com’);<\/p>\n\n\n\n

                                                  \n
                                                • UPDATE<\/strong>:<\/li>\n<\/ul>\n\n\n\n

                                                  sql<\/p>\n\n\n\n

                                                  CopyEdit<\/p>\n\n\n\n

                                                  UPDATE users SET email = ‘b@example.com’ WHERE id = 1;<\/p>\n\n\n\n

                                                    \n
                                                  • DELETE<\/strong>:<\/li>\n<\/ul>\n\n\n\n

                                                    sql<\/p>\n\n\n\n

                                                    CopyEdit<\/p>\n\n\n\n

                                                    DELETE FROM users WHERE id = 1;<\/p>\n\n\n\n

                                                    C\u00e2u l\u1ec7nh JOIN \u2013 K\u1ebft h\u1ee3p b\u1ea3ng d\u1eef li\u1ec7u<\/strong><\/p>\n\n\n\n

                                                    JOIN gi\u00fap k\u1ebft h\u1ee3p d\u1eef li\u1ec7u t\u1eeb nhi\u1ec1u b\u1ea3ng:<\/p>\n\n\n\n

                                                      \n
                                                    • INNER JOIN<\/strong> (ch\u1ec9 l\u1ea5y c\u00e1c b\u1ea3n ghi c\u00f3 li\u00ean k\u1ebft h\u1ee3p l\u1ec7 gi\u1eefa hai b\u1ea3ng):<\/li>\n<\/ul>\n\n\n\n

                                                      sql<\/p>\n\n\n\n

                                                      CopyEdit<\/p>\n\n\n\n

                                                      SELECT users.name, orders.order_id<\/p>\n\n\n\n

                                                      FROM users<\/p>\n\n\n\n

                                                      INNER JOIN orders ON users.id = orders.user_id;<\/p>\n\n\n\n

                                                        \n
                                                      • LEFT JOIN<\/strong> (l\u1ea5y t\u1ea5t c\u1ea3 d\u1eef li\u1ec7u t\u1eeb b\u1ea3ng b\u00ean tr\u00e1i, k\u1ec3 c\u1ea3 khi kh\u00f4ng c\u00f3 d\u1eef li\u1ec7u ph\u00f9 h\u1ee3p t\u1eeb b\u1ea3ng b\u00ean ph\u1ea3i):<\/li>\n<\/ul>\n\n\n\n

                                                        sql<\/p>\n\n\n\n

                                                        CopyEdit<\/p>\n\n\n\n

                                                        SELECT users.name, orders.order_id<\/p>\n\n\n\n

                                                        FROM users<\/p>\n\n\n\n

                                                        LEFT JOIN orders ON users.id = orders.user_id;<\/p>\n\n\n\n

                                                        SQL database v\u00e0 NoSQL<\/h2>\n\n\n\n

                                                        SQL v\u00e0 NoSQL l\u00e0 hai h\u1ec7 th\u1ed1ng c\u01a1 s\u1edf d\u1eef li\u1ec7u ph\u1ed5 bi\u1ebfn nh\u01b0ng c\u00f3 nh\u1eefng \u0111\u1eb7c \u0111i\u1ec3m v\u00e0 \u1ee9ng d\u1ee5ng kh\u00e1c nhau.<\/p>\n\n\n\n

                                                        So s\u00e1nh gi\u1eefa SQL v\u00e0 NoSQL<\/strong><\/p>\n\n\n\n

                                                        Ti\u00eau ch\u00ed<\/strong><\/td>SQL (C\u01a1 s\u1edf d\u1eef li\u1ec7u quan h\u1ec7)<\/strong><\/td>NoSQL (C\u01a1 s\u1edf d\u1eef li\u1ec7u phi quan h\u1ec7)<\/strong><\/td><\/tr><\/thead>
                                                        C\u1ea5u tr\u00fac d\u1eef li\u1ec7u<\/strong><\/td>D\u1eef li\u1ec7u \u0111\u01b0\u1ee3c l\u01b0u trong c\u00e1c b\u1ea3ng v\u1edbi quan h\u1ec7 gi\u1eefa c\u00e1c b\u1ea3ng<\/td>D\u1eef li\u1ec7u c\u00f3 th\u1ec3 l\u01b0u d\u01b0\u1edbi d\u1ea1ng key-value, document, column-family, ho\u1eb7c \u0111\u1ed3 th\u1ecb<\/td><\/tr>
                                                        Ng\u00f4n ng\u1eef truy v\u1ea5n<\/strong><\/td>S\u1eed d\u1ee5ng SQL v\u1edbi c\u00fa ph\u00e1p chu\u1ea9n<\/td>Kh\u00f4ng c\u00f3 ng\u00f4n ng\u1eef truy v\u1ea5n c\u1ed1 \u0111\u1ecbnh, m\u1ed7i h\u1ec7 qu\u1ea3n tr\u1ecb c\u00f3 c\u00e1ch kh\u00e1c nhau<\/td><\/tr>
                                                        T\u00ednh nh\u1ea5t qu\u00e1n<\/strong><\/td>H\u1ed7 tr\u1ee3 ACID (Atomicity, Consistency, Isolation, Durability)<\/td>H\u1ed7 tr\u1ee3 BASE (Basically Available, Soft state, Eventually consistent)<\/td><\/tr>
                                                        Kh\u1ea3 n\u0103ng m\u1edf r\u1ed9ng<\/strong><\/td>M\u1edf r\u1ed9ng theo chi\u1ec1u d\u1ecdc (Vertical Scaling)<\/td>M\u1edf r\u1ed9ng theo chi\u1ec1u ngang (Horizontal Scaling)<\/td><\/tr>
                                                        T\u1ed1c \u0111\u1ed9 x\u1eed l\u00fd<\/strong><\/td>T\u1ed1c \u0111\u1ed9 truy v\u1ea5n nhanh v\u1edbi d\u1eef li\u1ec7u c\u00f3 c\u1ea5u tr\u00fac r\u00f5 r\u00e0ng<\/td>Hi\u1ec7u su\u1ea5t cao h\u01a1n cho d\u1eef li\u1ec7u l\u1edbn v\u00e0 kh\u00f4ng c\u00f3 c\u1ea5u tr\u00fac c\u1ed1 \u0111\u1ecbnh<\/td><\/tr>
                                                        \u1ee8ng d\u1ee5ng ch\u00ednh<\/strong><\/td>H\u1ec7 th\u1ed1ng t\u00e0i ch\u00ednh, th\u01b0\u01a1ng m\u1ea1i \u0111i\u1ec7n t\u1eed, qu\u1ea3n l\u00fd doanh nghi\u1ec7p<\/td>Big Data, m\u1ea1ng x\u00e3 h\u1ed9i, IoT, l\u01b0u tr\u1eef t\u00e0i li\u1ec7u phi c\u1ea5u tr\u00fac<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

                                                        Khi n\u00e0o n\u00ean s\u1eed d\u1ee5ng SQL v\u00e0 khi n\u00e0o n\u00ean s\u1eed d\u1ee5ng NoSQL?<\/strong><\/p>\n\n\n\n

                                                          \n
                                                        • Ch\u1ecdn SQL khi:<\/strong>\n
                                                            \n
                                                          • D\u1eef li\u1ec7u c\u00f3 c\u1ea5u tr\u00fac r\u00f5 r\u00e0ng, c\u00f3 quan h\u1ec7 r\u00e0ng bu\u1ed9c gi\u1eefa c\u00e1c b\u1ea3ng.<\/li>\n\n\n\n
                                                          • C\u1ea7n \u0111\u1ea3m b\u1ea3o t\u00ednh nh\u1ea5t qu\u00e1n cao, ch\u1eb3ng h\u1ea1n trong h\u1ec7 th\u1ed1ng t\u00e0i ch\u00ednh, ng\u00e2n h\u00e0ng.<\/li>\n<\/ul>\n<\/li>\n\n\n\n
                                                          • Ch\u1ecdn NoSQL khi:<\/strong>\n
                                                              \n
                                                            • D\u1eef li\u1ec7u c\u00f3 quy m\u00f4 l\u1edbn, c\u1ea7n kh\u1ea3 n\u0103ng m\u1edf r\u1ed9ng nhanh ch\u00f3ng.<\/li>\n\n\n\n
                                                            • H\u1ec7 th\u1ed1ng y\u00eau c\u1ea7u x\u1eed l\u00fd d\u1eef li\u1ec7u theo th\u1eddi gian th\u1ef1c, nh\u01b0 m\u1ea1ng x\u00e3 h\u1ed9i ho\u1eb7c AI.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n\n

                                                              C\u00e1c h\u1ec7 th\u1ed1ng NoSQL ph\u1ed5 bi\u1ebfn hi\u1ec7n nay<\/strong><\/p>\n\n\n\n

                                                                \n
                                                              • MongoDB:<\/strong> L\u01b0u tr\u1eef d\u1eef li\u1ec7u theo d\u1ea1ng t\u00e0i li\u1ec7u JSON, ph\u00f9 h\u1ee3p cho \u1ee9ng d\u1ee5ng web.<\/li>\n\n\n\n
                                                              • Cassandra:<\/strong> H\u1ed7 tr\u1ee3 ph\u00e2n t\u00e1n m\u1ea1nh m\u1ebd, \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng trong Big Data.<\/li>\n\n\n\n
                                                              • Redis:<\/strong> C\u01a1 s\u1edf d\u1eef li\u1ec7u d\u1ea1ng key-value, hi\u1ec7u su\u1ea5t cao cho caching.<\/li>\n\n\n\n
                                                              • Neo4j:<\/strong> CSDL \u0111\u1ed3 th\u1ecb d\u00f9ng cho ph\u00e2n t\u00edch quan h\u1ec7 gi\u1eefa c\u00e1c \u0111\u1ed1i t\u01b0\u1ee3ng.<\/li>\n<\/ul>\n\n\n\n

                                                                C\u00e1c h\u1ec7 qu\u1ea3n tr\u1ecb c\u01a1 s\u1edf d\u1eef li\u1ec7u ph\u1ed5 bi\u1ebfn<\/h2>\n\n\n\n

                                                                Hi\u1ec7n nay, c\u00f3 nhi\u1ec1u h\u1ec7 qu\u1ea3n tr\u1ecb SQL ph\u1ed5 bi\u1ebfn, m\u1ed7i h\u1ec7 th\u1ed1ng c\u00f3 \u01b0u v\u00e0 nh\u01b0\u1ee3c \u0111i\u1ec3m ri\u00eang.<\/p>\n\n\n\n

                                                                MySQL \u2013 H\u1ec7 qu\u1ea3n tr\u1ecb m\u00e3 ngu\u1ed3n m\u1edf ph\u1ed5 bi\u1ebfn<\/strong><\/p>\n\n\n\n

                                                                  \n
                                                                • Ph\u00f9 h\u1ee3p v\u1edbi \u1ee9ng d\u1ee5ng web, th\u01b0\u01a1ng m\u1ea1i \u0111i\u1ec7n t\u1eed.<\/li>\n\n\n\n
                                                                • H\u1ed7 tr\u1ee3 nhi\u1ec1u t\u00ednh n\u0103ng m\u1ea1nh m\u1ebd, c\u00f3 phi\u00ean b\u1ea3n mi\u1ec5n ph\u00ed.<\/li>\n\n\n\n
                                                                • C\u1ed9ng \u0111\u1ed3ng l\u1edbn, d\u1ec5 d\u00e0ng t\u00ecm ki\u1ebfm t\u00e0i li\u1ec7u h\u1ed7 tr\u1ee3.<\/li>\n<\/ul>\n\n\n\n

                                                                  PostgreSQL \u2013 Gi\u1ea3i ph\u00e1p m\u1ea1nh m\u1ebd cho doanh nghi\u1ec7p<\/strong><\/p>\n\n\n\n

                                                                    \n
                                                                  • Cung c\u1ea5p nhi\u1ec1u t\u00ednh n\u0103ng n\u00e2ng cao nh\u01b0 JSONB, Index \u0111a d\u1ea1ng.<\/li>\n\n\n\n
                                                                  • H\u1ed7 tr\u1ee3 x\u1eed l\u00fd d\u1eef li\u1ec7u l\u1edbn, ph\u00f9 h\u1ee3p v\u1edbi AI, ph\u00e2n t\u00edch d\u1eef li\u1ec7u.<\/li>\n\n\n\n
                                                                  • \u0110\u1ed9 tin c\u1eady v\u00e0 t\u00ednh b\u1ea3o m\u1eadt cao.<\/li>\n<\/ul>\n\n\n\n

                                                                    Microsoft SQL Server \u2013 Gi\u1ea3i ph\u00e1p to\u00e0n di\u1ec7n c\u1ee7a Microsoft<\/strong><\/p>\n\n\n\n

                                                                      \n
                                                                    • H\u1ed7 tr\u1ee3 t\u00edch h\u1ee3p t\u1ed1t v\u1edbi h\u1ec7 sinh th\u00e1i Microsoft.<\/li>\n\n\n\n
                                                                    • Ph\u00f9 h\u1ee3p v\u1edbi doanh nghi\u1ec7p v\u1eeba v\u00e0 l\u1edbn.<\/li>\n\n\n\n
                                                                    • C\u00f3 t\u00ednh n\u0103ng ph\u00e2n t\u00edch v\u00e0 AI t\u00edch h\u1ee3p s\u1eb5n.<\/li>\n<\/ul>\n\n\n\n

                                                                      Oracle Database \u2013 H\u1ec7 qu\u1ea3n tr\u1ecb SQL d\u00e0nh cho doanh nghi\u1ec7p l\u1edbn<\/strong><\/p>\n\n\n\n

                                                                        \n
                                                                      • Hi\u1ec7u su\u1ea5t cao, b\u1ea3o m\u1eadt m\u1ea1nh m\u1ebd.<\/li>\n\n\n\n
                                                                      • Th\u01b0\u1eddng \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng trong c\u00e1c h\u1ec7 th\u1ed1ng t\u00e0i ch\u00ednh, ng\u00e2n h\u00e0ng.<\/li>\n\n\n\n
                                                                      • Chi ph\u00ed cao nh\u01b0ng cung c\u1ea5p nhi\u1ec1u t\u00ednh n\u0103ng m\u1ea1nh m\u1ebd.<\/li>\n<\/ul>\n\n\n\n

                                                                        SQLite \u2013 H\u1ec7 qu\u1ea3n tr\u1ecb nh\u1eb9 v\u00e0 d\u1ec5 s\u1eed d\u1ee5ng<\/strong><\/p>\n\n\n\n

                                                                          \n
                                                                        • Kh\u00f4ng c\u1ea7n c\u00e0i \u0111\u1eb7t m\u00e1y ch\u1ee7, ph\u00f9 h\u1ee3p cho \u1ee9ng d\u1ee5ng di \u0111\u1ed9ng.<\/li>\n\n\n\n
                                                                        • \u0110\u01b0\u1ee3c s\u1eed d\u1ee5ng r\u1ed9ng r\u00e3i trong c\u00e1c thi\u1ebft b\u1ecb nh\u00fang.<\/li>\n\n\n\n
                                                                        • H\u1ea1n ch\u1ebf v\u1ec1 t\u00ednh n\u0103ng so v\u1edbi c\u00e1c h\u1ec7 qu\u1ea3n tr\u1ecb l\u1edbn kh\u00e1c.<\/li>\n<\/ul>\n\n\n\n

                                                                          \u1ee8ng d\u1ee5ng c\u1ee7a SQL trong th\u1ef1c t\u1ebf<\/h2>\n\n\n\n

                                                                          SQL \u0111\u01b0\u1ee3c \u1ee9ng d\u1ee5ng r\u1ed9ng r\u00e3i trong nhi\u1ec1u l\u0129nh v\u1ef1c, t\u1eeb qu\u1ea3n l\u00fd d\u1eef li\u1ec7u doanh nghi\u1ec7p \u0111\u1ebfn ph\u00e1t tri\u1ec3n ph\u1ea7n m\u1ec1m.<\/p>\n\n\n\n

                                                                          SQL trong ph\u00e2n t\u00edch d\u1eef li\u1ec7u v\u00e0 khoa h\u1ecdc d\u1eef li\u1ec7u<\/h3>\n\n\n\n
                                                                            \n
                                                                          • Truy xu\u1ea5t d\u1eef li\u1ec7u t\u1eeb h\u1ec7 th\u1ed1ng l\u1edbn \u0111\u1ec3 ph\u00e2n t\u00edch xu h\u01b0\u1edbng kinh doanh.<\/li>\n\n\n\n
                                                                          • S\u1eed d\u1ee5ng SQL k\u1ebft h\u1ee3p v\u1edbi Python, R \u0111\u1ec3 l\u00e0m s\u1ea1ch v\u00e0 x\u1eed l\u00fd d\u1eef li\u1ec7u.<\/li>\n\n\n\n
                                                                          • H\u1ed7 tr\u1ee3 c\u00e1c c\u00f4ng c\u1ee5 BI (Business Intelligence) nh\u01b0 Power BI, Tableau.<\/li>\n<\/ul>\n\n\n\n

                                                                            SQL trong l\u1eadp tr\u00ecnh v\u00e0 ph\u00e1t tri\u1ec3n \u1ee9ng d\u1ee5ng<\/h3>\n\n\n\n
                                                                              \n
                                                                            • SQL l\u00e0 n\u1ec1n t\u1ea3ng c\u1ee7a c\u00e1c \u1ee9ng d\u1ee5ng web v\u00e0 di \u0111\u1ed9ng.<\/li>\n\n\n\n
                                                                            • C\u00e1c framework ph\u1ed5 bi\u1ebfn nh\u01b0 Django, Laravel, Spring Boot \u0111\u1ec1u h\u1ed7 tr\u1ee3 SQL.<\/li>\n\n\n\n
                                                                            • H\u1ec7 th\u1ed1ng qu\u1ea3n l\u00fd n\u1ed9i dung (CMS) nh\u01b0 WordPress c\u0169ng s\u1eed d\u1ee5ng SQL.<\/li>\n<\/ul>\n\n\n\n

                                                                              SQL trong qu\u1ea3n l\u00fd doanh nghi\u1ec7p v\u00e0 ERP<\/h3>\n\n\n\n
                                                                                \n
                                                                              • H\u1ed7 tr\u1ee3 ph\u1ea7n m\u1ec1m ERP nh\u01b0 SAP, Oracle ERP qu\u1ea3n l\u00fd t\u00e0i ch\u00ednh, nh\u00e2n s\u1ef1.<\/li>\n\n\n\n
                                                                              • Gi\u00fap doanh nghi\u1ec7p theo d\u00f5i d\u1eef li\u1ec7u kh\u00e1ch h\u00e0ng, h\u00e0ng t\u1ed3n kho.<\/li>\n\n\n\n
                                                                              • Cung c\u1ea5p kh\u1ea3 n\u0103ng t\u1ef1 \u0111\u1ed9ng h\u00f3a quy tr\u00ecnh kinh doanh v\u1edbi Stored Procedures.<\/li>\n<\/ul>\n\n\n\n

                                                                                \u01afu \u0111i\u1ec3m v\u00e0 nh\u01b0\u1ee3c \u0111i\u1ec3m SQL Database<\/h2>\n\n\n\n

                                                                                SQL l\u00e0 m\u1ed9t trong nh\u1eefng ng\u00f4n ng\u1eef quan tr\u1ecdng nh\u1ea5t trong l\u0129nh v\u1ef1c c\u00f4ng ngh\u1ec7 th\u00f4ng tin, \u0111\u1eb7c bi\u1ec7t trong qu\u1ea3n l\u00fd v\u00e0 truy v\u1ea5n d\u1eef li\u1ec7u. Tuy nhi\u00ean, gi\u1ed1ng nh\u01b0 b\u1ea5t k\u1ef3 c\u00f4ng ngh\u1ec7 n\u00e0o, SQL c\u0169ng c\u00f3 nh\u1eefng \u01b0u \u0111i\u1ec3m v\u00e0 h\u1ea1n ch\u1ebf c\u1ea7n \u0111\u01b0\u1ee3c xem x\u00e9t.<\/p>\n\n\n\n

                                                                                \u01afu \u0111i\u1ec3m c\u1ee7a SQL Database<\/h3>\n\n\n\n

                                                                                C\u1ea5u tr\u00fac d\u1eef li\u1ec7u c\u00f3 t\u1ed5 ch\u1ee9c<\/strong><\/p>\n\n\n\n

                                                                                  \n
                                                                                • SQL Database l\u01b0u tr\u1eef d\u1eef li\u1ec7u theo m\u00f4 h\u00ecnh quan h\u1ec7 (b\u1ea3ng, h\u00e0ng, c\u1ed9t), gi\u00fap d\u1ec5 d\u00e0ng qu\u1ea3n l\u00fd v\u00e0 truy xu\u1ea5t.<\/li>\n\n\n\n
                                                                                • D\u1eef li\u1ec7u c\u00f3 s\u1ef1 li\u00ean k\u1ebft ch\u1eb7t ch\u1ebd, \u0111\u1ea3m b\u1ea3o t\u00ednh to\u00e0n v\u1eb9n v\u00e0 nh\u1ea5t qu\u00e1n.<\/li>\n<\/ul>\n\n\n\n

                                                                                  Truy v\u1ea5n v\u00e0 x\u1eed l\u00fd d\u1eef li\u1ec7u m\u1ea1nh m\u1ebd<\/strong><\/p>\n\n\n\n

                                                                                    \n
                                                                                  • SQL h\u1ed7 tr\u1ee3 c\u00e1c c\u00e2u l\u1ec7nh truy v\u1ea5n linh ho\u1ea1t nh\u01b0 SELECT, JOIN, GROUP BY, gi\u00fap l\u1ea5y d\u1eef li\u1ec7u nhanh ch\u00f3ng.<\/li>\n\n\n\n
                                                                                  • H\u1ed7 tr\u1ee3 t\u1ed1i \u01b0u h\u00f3a truy v\u1ea5n b\u1eb1ng Index, Views, Stored Procedures \u0111\u1ec3 t\u0103ng hi\u1ec7u su\u1ea5t.<\/li>\n<\/ul>\n\n\n\n

                                                                                    \u0110\u1ed9 b\u1ea3o m\u1eadt cao v\u00e0 ki\u1ec3m so\u00e1t truy c\u1eadp t\u1ed1t<\/strong><\/p>\n\n\n\n

                                                                                      \n
                                                                                    • H\u1ed7 tr\u1ee3 ph\u00e2n quy\u1ec1n ng\u01b0\u1eddi d\u00f9ng v\u1edbi GRANT v\u00e0 REVOKE \u0111\u1ec3 ki\u1ec3m so\u00e1t quy\u1ec1n truy c\u1eadp.<\/li>\n\n\n\n
                                                                                    • C\u00f3 th\u1ec3 m\u00e3 h\u00f3a d\u1eef li\u1ec7u, h\u1ea1n ch\u1ebf r\u1ee7i ro b\u1ea3o m\u1eadt nh\u01b0 SQL Injection.<\/li>\n<\/ul>\n\n\n\n

                                                                                      H\u1ed7 tr\u1ee3 giao d\u1ecbch v\u00e0 \u0111\u1ea3m b\u1ea3o t\u00ednh nh\u1ea5t qu\u00e1n d\u1eef li\u1ec7u<\/strong><\/p>\n\n\n\n

                                                                                        \n
                                                                                      • Tu\u00e2n th\u1ee7 nguy\u00ean t\u1eafc ACID<\/strong> (Atomicity, Consistency, Isolation, Durability), gi\u00fap \u0111\u1ea3m b\u1ea3o d\u1eef li\u1ec7u ch\u00ednh x\u00e1c ngay c\u1ea3 khi h\u1ec7 th\u1ed1ng g\u1eb7p l\u1ed7i.<\/li>\n<\/ul>\n\n\n\n

                                                                                        T\u01b0\u01a1ng th\u00edch v\u00e0 m\u1edf r\u1ed9ng t\u1ed1t<\/strong><\/p>\n\n\n\n

                                                                                          \n
                                                                                        • SQL Database c\u00f3 th\u1ec3 m\u1edf r\u1ed9ng theo chi\u1ec1u d\u1ecdc (Vertical Scaling) \u0111\u1ec3 x\u1eed l\u00fd d\u1eef li\u1ec7u l\u1edbn.<\/li>\n\n\n\n
                                                                                        • H\u1ed7 tr\u1ee3 t\u00edch h\u1ee3p v\u1edbi nhi\u1ec1u \u1ee9ng d\u1ee5ng, c\u00f4ng c\u1ee5 BI, h\u1ec7 th\u1ed1ng Cloud nh\u01b0 AWS RDS, Google Cloud SQL.<\/li>\n<\/ul>\n\n\n\n

                                                                                          Nh\u01b0\u1ee3c \u0111i\u1ec3m c\u1ee7a SQL Database<\/h3>\n\n\n\n

                                                                                          H\u1ea1n ch\u1ebf trong kh\u1ea3 n\u0103ng m\u1edf r\u1ed9ng ngang (Horizontal Scaling)<\/strong><\/p>\n\n\n\n

                                                                                            \n
                                                                                          • SQL Database ch\u1ee7 y\u1ebfu m\u1edf r\u1ed9ng theo chi\u1ec1u d\u1ecdc (Vertical Scaling<\/em>), t\u1ee9c l\u00e0 n\u00e2ng c\u1ea5p ph\u1ea7n c\u1ee9ng thay v\u00ec ph\u00e2n t\u00e1n d\u1eef li\u1ec7u tr\u00ean nhi\u1ec1u m\u00e1y ch\u1ee7.<\/li>\n\n\n\n
                                                                                          • Khi d\u1eef li\u1ec7u qu\u00e1 l\u1edbn, hi\u1ec7u su\u1ea5t c\u00f3 th\u1ec3 b\u1ecb suy gi\u1ea3m v\u00e0 kh\u00f3 m\u1edf r\u1ed9ng h\u01a1n so v\u1edbi NoSQL.<\/li>\n<\/ul>\n\n\n\n

                                                                                            Hi\u1ec7u su\u1ea5t gi\u1ea3m khi truy v\u1ea5n ph\u1ee9c t\u1ea1p v\u1edbi d\u1eef li\u1ec7u l\u1edbn<\/strong><\/p>\n\n\n\n

                                                                                              \n
                                                                                            • N\u1ebfu kh\u00f4ng \u0111\u01b0\u1ee3c t\u1ed1i \u01b0u h\u00f3a, c\u00e1c truy v\u1ea5n SQL c\u00f3 th\u1ec3 ch\u1eadm khi d\u1eef li\u1ec7u t\u0103ng cao.<\/li>\n\n\n\n
                                                                                            • M\u1ed9t s\u1ed1 ph\u00e9p to\u00e1n nh\u01b0 JOIN, GROUP BY, ORDER BY ti\u00eau t\u1ed1n nhi\u1ec1u t\u00e0i nguy\u00ean n\u1ebfu b\u1ea3ng c\u00f3 h\u00e0ng tri\u1ec7u b\u1ea3n ghi.<\/li>\n<\/ul>\n\n\n\n

                                                                                              C\u1ea5u tr\u00fac d\u1eef li\u1ec7u c\u1ee9ng nh\u1eafc, kh\u00f3 thay \u0111\u1ed5i<\/strong><\/p>\n\n\n\n

                                                                                                \n
                                                                                              • SQL y\u00eau c\u1ea7u d\u1eef li\u1ec7u c\u00f3 c\u1ea5u tr\u00fac c\u1ed1 \u0111\u1ecbnh, m\u1ed7i b\u1ea3ng ph\u1ea3i c\u00f3 \u0111\u1ecbnh ngh\u0129a r\u00f5 r\u00e0ng v\u1ec1 c\u1ed9t v\u00e0 ki\u1ec3u d\u1eef li\u1ec7u.<\/li>\n\n\n\n
                                                                                              • Vi\u1ec7c thay \u0111\u1ed5i c\u1ea5u tr\u00fac b\u1ea3ng (ALTER TABLE) tr\u00ean c\u01a1 s\u1edf d\u1eef li\u1ec7u l\u1edbn c\u00f3 th\u1ec3 g\u00e2y gi\u00e1n \u0111o\u1ea1n h\u1ec7 th\u1ed1ng.<\/li>\n<\/ul>\n\n\n\n

                                                                                                Nguy c\u01a1 b\u1ea3o m\u1eadt \u2013 SQL Injection<\/strong><\/p>\n\n\n\n

                                                                                                  \n
                                                                                                • N\u1ebfu kh\u00f4ng ki\u1ec3m so\u00e1t d\u1eef li\u1ec7u \u0111\u1ea7u v\u00e0o t\u1ed1t, h\u1ec7 th\u1ed1ng c\u00f3 th\u1ec3 b\u1ecb t\u1ea5n c\u00f4ng SQL Injection, d\u1eabn \u0111\u1ebfn r\u00f2 r\u1ec9 ho\u1eb7c thay \u0111\u1ed5i d\u1eef li\u1ec7u tr\u00e1i ph\u00e9p.<\/li>\n\n\n\n
                                                                                                • C\u1ea7n s\u1eed d\u1ee5ng Prepared Statements \u0111\u1ec3 tr\u00e1nh l\u1ed7 h\u1ed5ng b\u1ea3o m\u1eadt n\u00e0y.<\/li>\n<\/ul>\n\n\n\n

                                                                                                  Chi ph\u00ed cao khi s\u1eed d\u1ee5ng c\u00e1c h\u1ec7 qu\u1ea3n tr\u1ecb SQL th\u01b0\u01a1ng m\u1ea1i<\/strong><\/p>\n\n\n\n

                                                                                                    \n
                                                                                                  • C\u00e1c h\u1ec7 qu\u1ea3n tr\u1ecb SQL nh\u01b0 Oracle Database, Microsoft SQL Server c\u00f3 chi ph\u00ed b\u1ea3n quy\u1ec1n cao.<\/li>\n\n\n\n
                                                                                                  • Y\u00eau c\u1ea7u ph\u1ea7n c\u1ee9ng m\u1ea1nh \u0111\u1ec3 \u0111\u1ea3m b\u1ea3o hi\u1ec7u su\u1ea5t v\u1edbi d\u1eef li\u1ec7u l\u1edbn.<\/li>\n<\/ul>\n\n\n\n

                                                                                                    M\u1ee9c l\u01b0\u01a1ng l\u1eadp tr\u00ecnh SQL database bao nhi\u00eau<\/h2>\n\n\n\n

                                                                                                    M\u1ee9c l\u01b0\u01a1ng c\u1ee7a l\u1eadp tr\u00ecnh vi\u00ean SQL ph\u1ee5 thu\u1ed9c v\u00e0o nhi\u1ec1u y\u1ebfu t\u1ed1 nh\u01b0 kinh nghi\u1ec7m, v\u1ecb tr\u00ed l\u00e0m vi\u1ec7c v\u00e0 k\u1ef9 n\u0103ng chuy\u00ean m\u00f4n. D\u01b0\u1edbi \u0111\u00e2y l\u00e0 m\u1ed9t s\u1ed1 th\u00f4ng tin chi ti\u1ebft:<\/p>\n\n\n\n

                                                                                                    M\u1ee9c l\u01b0\u01a1ng trung b\u00ecnh<\/strong><\/p>\n\n\n\n

                                                                                                    Theo th\u1ed1ng k\u00ea, m\u1ee9c l\u01b0\u01a1ng trung b\u00ecnh c\u1ee7a l\u1eadp tr\u00ecnh vi\u00ean t\u1ea1i Vi\u1ec7t Nam dao \u0111\u1ed9ng t\u1eeb 27 tri\u1ec7u \u0111\u1ebfn h\u01a1n 73 tri\u1ec7u \u0111\u1ed3ng m\u1ed7i th\u00e1ng, t\u00f9y thu\u1ed9c v\u00e0o k\u1ef9 n\u0103ng v\u00e0 kinh nghi\u1ec7m.  <\/p>\n\n\n\n

                                                                                                    Theo kinh nghi\u1ec7m<\/strong><\/p>\n\n\n\n

                                                                                                      \n
                                                                                                    • Fresher (d\u01b0\u1edbi 1 n\u0103m kinh nghi\u1ec7m):<\/strong> M\u1ee9c l\u01b0\u01a1ng kh\u1edfi \u0111i\u1ec3m kho\u1ea3ng 8,3 tri\u1ec7u \u0111\u1ed3ng\/th\u00e1ng.\u200b<\/li>\n\n\n\n
                                                                                                    • Mid-Senior (tr\u00ean 3 n\u0103m kinh nghi\u1ec7m):<\/strong> M\u1ee9c l\u01b0\u01a1ng c\u00f3 th\u1ec3 \u0111\u1ea1t t\u1eeb 28 tri\u1ec7u \u0111\u1ed3ng\/th\u00e1ng tr\u1edf l\u00ean.\u200b<\/li>\n\n\n\n
                                                                                                    • Senior (tr\u00ean 5 n\u0103m kinh nghi\u1ec7m):<\/strong> M\u1ee9c l\u01b0\u01a1ng dao \u0111\u1ed9ng t\u1eeb 33 tri\u1ec7u \u0111\u1ebfn h\u01a1n 54 tri\u1ec7u \u0111\u1ed3ng\/th\u00e1ng.<\/li>\n<\/ul>\n\n\n\n

                                                                                                      Theo khu v\u1ef1c<\/strong><\/p>\n\n\n\n

                                                                                                        \n
                                                                                                      • H\u00e0 N\u1ed9i:<\/strong> M\u1ee9c l\u01b0\u01a1ng trung b\u00ecnh kho\u1ea3ng 17,1 tri\u1ec7u \u0111\u1ed3ng\/th\u00e1ng.\u200b<\/li>\n\n\n\n
                                                                                                      • Th\u00e0nh ph\u1ed1 H\u1ed3 Ch\u00ed Minh:<\/strong> M\u1ee9c l\u01b0\u01a1ng trung b\u00ecnh kho\u1ea3ng 17,9 tri\u1ec7u \u0111\u1ed3ng\/th\u00e1ng. \u200b<\/li>\n<\/ul>\n\n\n\n

                                                                                                        Theo ng\u00f4n ng\u1eef l\u1eadp tr\u00ecnh<\/strong><\/p>\n\n\n\n

                                                                                                        M\u1ee9c l\u01b0\u01a1ng c\u1ee7a l\u1eadp tr\u00ecnh vi\u00ean c\u0169ng ph\u1ee5 thu\u1ed9c v\u00e0o ng\u00f4n ng\u1eef l\u1eadp tr\u00ecnh m\u00e0 h\u1ecd s\u1eed d\u1ee5ng. V\u00ed d\u1ee5, l\u1eadp tr\u00ecnh vi\u00ean Java ho\u1eb7c C++ c\u00f3 th\u1ec3 nh\u1eadn m\u1ee9c l\u01b0\u01a1ng cao h\u01a1n so v\u1edbi m\u1ed9t s\u1ed1 ng\u00f4n ng\u1eef kh\u00e1c. \u200b<\/p>\n\n\n\n

                                                                                                        L\u01b0u \u00fd r\u1eb1ng c\u00e1c con s\u1ed1 tr\u00ean ch\u1ec9 mang t\u00ednh ch\u1ea5t tham kh\u1ea3o v\u00e0 c\u00f3 th\u1ec3 thay \u0111\u1ed5i t\u00f9y thu\u1ed9c v\u00e0o t\u1eebng c\u00f4ng ty, d\u1ef1 \u00e1n c\u1ee5 th\u1ec3 v\u00e0 kh\u1ea3 n\u0103ng c\u1ee7a l\u1eadp tr\u00ecnh vi\u00ean.\u200b<\/em><\/p>\n\n\n\n

                                                                                                        Nh\u1eefng c\u00e2u h\u1ecfi th\u01b0\u1eddng g\u1eb7p v\u1ec1 SQL<\/h2>\n\n\n\n

                                                                                                        SQL l\u00e0 m\u1ed9t ch\u1ee7 \u0111\u1ec1 quan tr\u1ecdng trong qu\u1ea3n l\u00fd d\u1eef li\u1ec7u, v\u00e0 d\u01b0\u1edbi \u0111\u00e2y l\u00e0 nh\u1eefng c\u00e2u h\u1ecfi th\u01b0\u1eddng g\u1eb7p \u0111\u1ec3 gi\u00fap ng\u01b0\u1eddi \u0111\u1ecdc hi\u1ec3u r\u00f5 h\u01a1n v\u1ec1 SQL.<\/p>\n\n\n\n

                                                                                                        SQL c\u00f3 kh\u00f3 h\u1ecdc kh\u00f4ng? Ai n\u00ean h\u1ecdc SQL?<\/em><\/strong><\/p>\n\n\n\n

                                                                                                        SQL kh\u00f4ng kh\u00f3 h\u1ecdc n\u1ebfu b\u1ea1n c\u00f3 ki\u1ebfn th\u1ee9c c\u01a1 b\u1ea3n v\u1ec1 d\u1eef li\u1ec7u v\u00e0 t\u01b0 duy logic.<\/p>\n\n\n\n

                                                                                                        C\u00f3 nh\u1eefng ch\u1ee9ng ch\u1ec9 n\u00e0o gi\u00fap \u0111\u00e1nh gi\u00e1 tr\u00ecnh \u0111\u1ed9 SQL?<\/em><\/strong><\/p>\n\n\n\n

                                                                                                        Microsoft Certified: Azure Database Administrator Associate \u2013 Ch\u1ee9ng ch\u1ec9 c\u1ee7a Microsoft.<\/p>\n\n\n\n

                                                                                                        Oracle Database SQL Certified Associate \u2013 Ch\u1ee9ng ch\u1ec9 c\u1ee7a Oracle.<\/p>\n\n\n\n

                                                                                                        IBM Certified Database Administrator \u2013 Ch\u1ee9ng ch\u1ec9 c\u1ee7a IBM.<\/p>\n\n\n\n

                                                                                                        Google Cloud Professional Data Engineer \u2013 D\u00e0nh cho ng\u01b0\u1eddi l\u00e0m vi\u1ec7c v\u1edbi SQL tr\u00ean Google Cloud.<\/p>\n\n\n\n

                                                                                                        SQL c\u00f3 ph\u00f9 h\u1ee3p v\u1edbi ph\u00e1t tri\u1ec3n \u1ee9ng d\u1ee5ng web kh\u00f4ng?<\/em><\/strong><\/p>\n\n\n\n

                                                                                                        C\u00f3, SQL l\u00e0 n\u1ec1n t\u1ea3ng c\u1ee7a h\u1ea7u h\u1ebft c\u00e1c \u1ee9ng d\u1ee5ng web v\u00ec gi\u00fap H\u1ed7 tr\u1ee3 truy v\u1ea5n d\u1eef li\u1ec7u nhanh ch\u00f3ng v\u00e0 t\u00edch h\u1ee3p t\u1ed1t v\u1edbi c\u00e1c framework nh\u01b0 Django (Python), Laravel (PHP), Spring Boot (Java).<\/p>\n\n\n\n

                                                                                                        Tr\u00ean \u0111\u00e2y l\u00e0 nh\u1eefng th\u00f4ng tin gi\u00fap b\u1ea1n hi\u1ec3u r\u00f5 SQL l\u00e0 g\u00ec<\/strong> v\u00e0 vai tr\u00f2 SQL trong qu\u1ea3n l\u00fd d\u1eef li\u1ec7u. N\u1ebfu b\u1ea1n \u0111ang mu\u1ed1n n\u00e2ng cao k\u1ef9 n\u0103ng v\u1ec1 SQL \u0111\u1ec3 \u1ee9ng d\u1ee5ng trong c\u00f4ng vi\u1ec7c l\u1eadp tr\u00ecnh, ph\u00e2n t\u00edch d\u1eef li\u1ec7u hay qu\u1ea3n tr\u1ecb c\u01a1 s\u1edf d\u1eef li\u1ec7u, h\u00e3y b\u1eaft \u0111\u1ea7u ngay t\u1eeb h\u00f4m nay. Ch\u00fac b\u1ea1n th\u00e0nh c\u00f4ng.<\/p>\n\n\n\n

                                                                                                        Tr\u00ed Nh\u00e2n<\/strong><\/p>\n\n\n\n

                                                                                                        <\/p>\n","protected":false},"excerpt":{"rendered":"

                                                                                                        C\u01a1 s\u1edf d\u1eef li\u1ec7u l\u00e0 m\u1ed9t ph\u1ea7n quan tr\u1ecdng trong c\u00f4ng ngh\u1ec7 th\u00f4ng tin, gi\u00fap l\u01b0u tr\u1eef v\u00e0 qu\u1ea3n l\u00fd d\u1eef li\u1ec7u m\u1ed9t c\u00e1ch hi\u1ec7u …<\/p>\n","protected":false},"author":58,"featured_media":8810,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[17],"tags":[64],"class_list":["post-8809","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-tu-van-nghe-nghiep","tag-it"],"_links":{"self":[{"href":"https:\/\/mb668s.com\/cam-nang-7mb66-xoc-dia\/wp-json\/wp\/v2\/posts\/8809","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/mb668s.com\/cam-nang-7mb66-xoc-dia\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mb668s.com\/cam-nang-7mb66-xoc-dia\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mb668s.com\/cam-nang-7mb66-xoc-dia\/wp-json\/wp\/v2\/users\/58"}],"replies":[{"embeddable":true,"href":"https:\/\/mb668s.com\/cam-nang-7mb66-xoc-dia\/wp-json\/wp\/v2\/comments?post=8809"}],"version-history":[{"count":11,"href":"https:\/\/mb668s.com\/cam-nang-7mb66-xoc-dia\/wp-json\/wp\/v2\/posts\/8809\/revisions"}],"predecessor-version":[{"id":15664,"href":"https:\/\/mb668s.com\/cam-nang-7mb66-xoc-dia\/wp-json\/wp\/v2\/posts\/8809\/revisions\/15664"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/mb668s.com\/cam-nang-7mb66-xoc-dia\/wp-json\/wp\/v2\/media\/8810"}],"wp:attachment":[{"href":"https:\/\/mb668s.com\/cam-nang-7mb66-xoc-dia\/wp-json\/wp\/v2\/media?parent=8809"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mb668s.com\/cam-nang-7mb66-xoc-dia\/wp-json\/wp\/v2\/categories?post=8809"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mb668s.com\/cam-nang-7mb66-xoc-dia\/wp-json\/wp\/v2\/tags?post=8809"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}