Introduction to RDBMS (Relational Database Management System)
In this article, I am going to give you a brief introduction to RDMB (Relational Database Management System). Please read our previous article where we discussed Data Models in DBMS. At the end of this article, you will understand the following pointers in detail.
- What is DBMS?
- What is RDBMS?
- Features of RDBMS
- Advantages of RDBMS
- DBMS vs RDBMS
- E.F. Codd’s Rules
What is DBMS?
DBMS is a software or group of programs designed to perform database operations such as creating a new database, administering and managing the databases by performing various user-specified database operations. The DBMS internally might consist of a group of programs each performing different tasks related to database management. Some DBMS examples, My SQL, Oracle, System 2000, MS Access, My SQL server, etc.
What is RDBMS?
RDBMS is the collection of programs and capabilities that enables the user to interact with a relational database. A relational database management system (RDBMS) is a type of DBMS with a row-based table structure. Most commercial RDBMSes use SQL. The most basic RDBMS functions are related to create, read, update and delete operations, collectively known as the CRUD cycle.
Features of RDBMS:
- An RDBMS is easily accessible using SQL commands.
- An RDBMS provides full data independence.
- The basic unit of data storage in a relational database is called a table.
- A table consists of tuples/rows/records and each record has one or more columns used to store values.
- In RDBMS, we can use conditional operations such as joins and restrictions.
- An RDBMS enables data sharing between users.
- Also at the same time, you can ensure consistency of data across multiple tables by using integrity constraints.
- An RDBMS minimizes the redundancy of data.
Features of SQL:
- High performance
- High availability
- Easy to learn and use
- Robust transactional support
- Functionally complete
- Highly secure
- Comprehensive application development
- Management ease
How to communicate with RDBMS?
The structured query language is used to communicate with RDBMS.
Advantages of RDBMS:
- Support for a very large database.
- Automatic optimization of searching (when possible).
- RDBMS has a simple view of the database that conforms to much of the data used in businesses.
- RDBMS uses Structured Query Language.
- Easy extendibility, as new data may be added without modifying existing records this is also known as scalability.
- RDBMS has data security which is critical when data sharing is based on privacy.
- RDBMS defines how the data is organized and how the relations among them are associated.
- It defines the entities and relationships among them. It contains a descriptive detail of the database.
Disadvantages of RDBMS:
- No support for complex objects such as documents, video, images.
- Often poor support for storage of complex objects.
- Still no efficient and effective integrated support.
DBMS vs RDBMS:
|The concept of a relationship is not there.||It is based on the concept of relationship.|
|The speed of operation is slow.||The speed of operation is fast|
|The hardware and software requirements are very low.||The hardware and software requirements are very high.|
|It uses the concept of files.||It uses the concept of tables.|
|The facilities and utilities offered are limited.||The facilities and utilities offered are not limited.|
|DBMS normally uses a 3GL.||RDBMS normally uses a 4GL.|
|Ex: Dbase, Fox base|
Ex: ORACLE, FOCUS
E.F. Codd’s Rules:
Rule 1: The information Rule.
“This rule requires that all information should be represented as data values in the rows and columns of the table. This is the basis of the relational model.”
Rule 2: The Guaranteed access Rule.
“Each data value in a relational database should be accessible logically by specifying the relation’s name, primary key value, and the attribute name.”
Rule 3: Systematic treatment of null values.
“DBMS must support NULL values to represent missing or inapplicable information. NULL values must be distinct from zero or spaces. It must be independent of data type.”
Rule 4: Active online catalog based on the relational model.
“System catalog is a collection of relations that the DBMS maintains for its own use. These relations hold the description of the structure of the database.”
Rule 5: Comprehensive data sub-language Rule.
“This rule states that the system must support at least all of the following functions.”
- Data Definition
- View Definition
- Data Manipulation Operation (Interactive and by program).
- Security and Integrity Constraints
- Transaction Management Operations
Rule 6: View updating Rule.
“All views which are theoretically updatable should be updatable by the system.”
Rule 7: High-level insert, update and delete.
“The rows should be treated as sets during insert, update and delete operation. The operation that modifies the database should deal with sets and not with single rows.”
Rule 8: Physical data independence Rule.
“The application programs must remain unchanged when any changes are made in storage representation or access methods.”
Rule 9: Logical data independence.
“The changes that do not modify any data stored in that relation, do not require changes to be made to the application program.”
Rule 10: Integrity independence Rule.
“Integrity constraints must be specified independently of application programs. They must be stored in the catalog.”
Rule 11: Distribution independence.
“Existing applications should operate successfully when the data is distributed. The physical location of data, the control program, and the application may be different but the distribution should not affect the functioning of the application.”
Rule 12: Non-subversion Rule.
“Database security and integrity should not be bypassed. The DBMS must ensure that no other level can bypass the constraints specified to maintain the integrity of the database.”
In the next article, I am going to discuss Why do we need database design? Here, in this article, I try to give you an overview of RDBMS (Relational Database Management System). I hope you enjoy this article.