Page 279 - Information_Practice_Fliipbook_Class11
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Execution of either of the above two queries,  will produce the following output (Table 9.33):
                                                 Table 9.33: Employees born in 1980.
                                                 +--------+----------+-------------+
                                                 | FName  | LName    |  DOB        |
                                                 +--------+----------+-------------+
                                                 | Raj    | Reddy    | 1980-06-13  |
                                                 | Naveen | Basra    | 1980-09-24  |
                                                 +--------+----------+-------------+


                 Let's Summarise


              Ø   Database Management System (DBMS) is a collection of programs that help define, construct, and manipulate
                  the database.
              Ø   Database  administrator  (DBA)  manages  the  entire  database  by  acquiring  resources  (both  hardware  and
                  software) and controlling access.

              Ø   Disadvantages of conventional file-based information systems:
                  •     Structural Data Dependence: A change in the structure of a file may require changes in the applications
                      programs that use this file.
                  •   Lack of Controls: It is hard to enforce rules for authorising legitimate access to users at different levels
                      of hierarchy.
                  •   Lack of Data Sharing: As different application programmers deal with common data but in different
                      format, sharing data becomes a challenge.
              Ø   The Data Base Management Systems offer several advantages over conventional file systems:
                  •   Sharing Data: As DBMS maintains a single data repository, all users have shared access to the same data.
                  •     Lack of Data Redundancy: Storing the data centrally in a single repository  avoids  the problem of data
                      redundancy.
                  •   Data  Independence: Columns  may  be  added or deleted,  data types  may  change,  but applications
                      programs do not change.
              Ø   Database Management System (DBMS) is a collection of programs that help define, construct, and manipulate
                  the database.
              Ø   Database  administrator  (DBA)  manages  the  entire  database  by  acquiring  resources  (both  hardware  and
                  software) and controlling access.
              Ø   Disadvantages of conventional file-based information systems:
                  •     Structural Data Dependence: A change in the structure of a file may require changes in the applications
                      programs that use this file.
                  •   Lack of Controls: It is hard to enforce rules for authorising legitimate access to users at different levels
                      of hierarchy.
                  •   Lack of Data Sharing: As different application programmers deal with common data but in different
                      format, sharing data becomes a challenge.

              Ø   The Data Base Management Systems offer several advantages over conventional file systems
                  •   Sharing Data: As DBMS maintains a single data repository, all users have shared access to the same data.
                  •     Lack of Data Redundancy: Storing the data centrally in a single repository  avoids  the problem of data
                      redundancy.
                  •   Data  Independence: Columns  may  be  added or deleted,  data types  may  change,  but applications
                      programs do not change.
                  •   Database Authorization: DBMS authenticates access to the database based on user name and password,
                      or value of an attribute. for example, a user may be allowed to access details of employees whose salary
                      does not exceed Rs 75000.



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