data base System VS file System

A Database Management System (DMS) is a combination of computer software, hardware, and information designed to electronically manipulate data via computer processing. Two types of database management systems are DBMS’s and FMS’s. In simple terms, a File Management System (FMS) is a Database Management System that allows access to single files or tables at a time. FMS’s accommodate flat files that have no relation to other files. The FMS was the predecessor for the Database Management System (DBMS), which allows access to multiple files or tables at a time (see Figure 1 below)

File Management Systems

Advantages	Disadvantages
1-Simpler to use	1-Typically does not support multi-user access
2-Less expensive·	2-Limited to smaller databases
3-Fits the needs of many small businesses and home users	3-Limited functionality (i.e. no support for complicated transactions, recovery, etc.)
4-Popular FMS’s are packaged along with the operating systems of personal computers (i.e. Microsoft Cardfile and Microsoft Works)	4-Decentralization of data
5-Good for database solutions for hand held devices such as Palm Pilot	5-Redundancy and Integrity issues

Typically, File Management Systems provide the following advantages and disadvantages: 

The goals of a File Management System can be summarized as follows (Calleri, 2001):

• Data Management.  An FMS should provide data management services to the application.
• Generality with respect to storage devices. The FMS data abstractions and access methods should remain unchanged irrespective of the devices involved in data storage.
• Validity. An FMS should guarantee that at any given moment the stored data reflect the operations performed on them.
• Protection. Illegal or potentially dangerous operations on the data should be controlled by the FMS.
• Concurrency. In multiprogramming systems, concurrent access to the data should be allowed with minimal differences.
• Performance. Compromise data access speed and data transfer rate with functionality.

From the point of view of an end user (or application) an FMS typically provides the following functionalities (Calleri, 2001): 

• File creation, modification and deletion.
• Ownership of files and access control on the basis of ownership permissions.
• Facilities to structure data within files (predefined record formats, etc).
• Facilities for maintaining data redundancies against technical failure (back-ups, disk mirroring, etc.).
• Logical identification and structuring of the data, via file names and hierarchical directory structures.

Database Management Systems

Database Management Systems provide the following advantages and disadvantages: 

Advantages	Disadvantages
Greater flexibility	Difficult to learn
Good for larger databases	Packaged separately from the operating system (i.e. Oracle, Microsoft Access, Lotus/IBM Approach, Borland Paradox, Claris FileMaker Pro)
Greater processing power	Slower processing speeds
Fits the needs of many medium to large-sized organizations	Requires skilled administrators
Storage for all relevant data	Expensive
Provides user views relevant to tasks performed
Ensures data integrity by managing transactions (ACID test = atomicity, consistency, isolation, durability)
Supports simultaneous access
Enforces design criteria in relation to data format and structure
Provides backup and recovery controls
Advanced security

The goals of a Database Management System can be summarized as follows (Connelly, Begg, and Strachan, 1999, pps. 54 – 60): 

• Data storage, retrieval, and update (while hiding the internal physical implementation details)
• A user-accessible catalog
• Transaction support
• Concurrency control services (multi-user update functionality)
• Recovery services (damaged database must be returned to a consistent state)
• Authorization services (security)
• Support for data communication Integrity services (i.e. constraints)
• Services to promote data independence
• Utility services (i.e. importing, monitoring, performance, record deletion, etc.)

The components to facilitate the goals of a DBMS may include the following:

• Query processor
• Data Manipulation Language preprocessor
• Database manager (software components to include authorization control, command processor, integrity checker, query optimizer, transaction manager, scheduler, recovery manager, and buffer manager)
• Data Definition Language compiler
• File manager