Question

List any four advantages of DBMS.

Answer 1

Of course. A Database Management System (DBMS) is software that allows users to create, maintain, and control access to a database. It serves as an interface between the user and the database, ensuring that data is consistently organized and remains easily accessible.

Here are four major advantages of using a DBMS over traditional file processing systems.

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1. Control of Data Redundancy and Inconsistency

• Description: In traditional file systems, the same piece of information is often stored in multiple, separate files. This duplication of data is called data redundancy. When data is redundant, any update to it must be made in all the different files where it is stored. If one or more files are missed, the data becomes conflicting, leading to data inconsistency.

• DBMS Advantage: A DBMS uses a centralized data repository and techniques like normalization to minimize or eliminate redundancy. Data is stored in only one place, and any application that needs it can reference that single, authoritative source. When an update is made, it is immediately reflected for all users, ensuring data consistency.

• Example: A university might store a student's address in a file for the Registrar's office and another file for the Library. If the student moves, their address might be updated in the Registrar's file but not the Library's. A DBMS would store the student's address in a single Students table, which both departments would access, thus eliminating this problem.

2. Improved Data Security and Access Control

• Description: In a file processing system, security is often limited to the operating system's permissions (e.g., read/write access to an entire file). It is very difficult to enforce fine-grained security policies, such as allowing a user to see some columns in a file but not others.

• DBMS Advantage: A DBMS provides a robust security and authorization subsystem. A Database Administrator (DBA) can create different user accounts and roles, granting them specific privileges. Access can be controlled down to the table, row, or even individual column level.

• Example: In an Employees table, a manager could be granted permission to SELECT all information for employees in their department, while a payroll clerk could be granted permission to UPDATE only the Salary column but not see personal addresses.

3. Efficient and Easy Data Access

• Description: In a file-based system, retrieving specific data requires a custom program to be written to parse the file. If a new type of query is needed, a new program has to be developed, which is time-consuming and requires a programmer.

• DBMS Advantage: A DBMS provides a high-level, standardized query language (like SQL) that allows both technical and non-technical users to ask complex questions of the data with relatively simple statements. This allows for powerful ad-hoc data retrieval without the need for custom application code.

• Example: A request like "Find the names of all customers from California who spent more than $500 in the last month" would require a complex program in a file system. In a DBMS, this can be answered with a single, readable SQL query.

4. Concurrent Access and Transaction Management

• Description: Most modern applications require multiple users to access and update the data simultaneously (concurrently). In a simple file system, this can lead to chaos. For example, if two users try to update the same record at the same time, one user's changes might overwrite and erase the other's (the "lost update" problem).

• DBMS Advantage: A DBMS has sophisticated concurrency control mechanisms (like locking) that manage simultaneous access. It also supports transactions which ensure that a series of operations is completed entirely or not at all (atomicity). This guarantees that the database remains in a consistent state even with many users making updates.

• Example: When two people try to book the last available seat on a flight at the exact same moment, the DBMS will lock the seat record for the first user's transaction, process their booking, and then inform the second user that the seat is no longer available, preventing a double-booking.