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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.
Database Concepts and the Structured Query Language 265

