Relational Database Management System (RDBMS)
What is RDBMS?
A Relational Database Management System (RDBMS) is a Database Management System based on relational model introduced by E.F Codd. In relational model data is represents in terms of rows.
A type of database in which data is organized across one or more tables. Tables are associated with each other through common fields called keys. In contrast to other database structures, an RDBMS requires few assumptions about how data is related or how it will be extracted from the database.
Usage
RDBMS is used to manage relational databases. Relational database is a collection of organized set of tables from which data can be access easily.
| Concept | Description |
|---|---|
| Primary Key | A unique identifier for each record in a table. |
| Foreign Key | A field that creates a link between two tables. |
| Normalization | Organizing data to reduce redundancy and improve data integrity. |
| Transaction | A sequence of operations performed as a single logical unit of work. |
| Index | Improves the speed of data retrieval operations. |
Table
A Relational database’s, table is a collection of data elements organized in trams of rows and columns. A table is a considered as convenient representation of relations. In below an example of marksheet table;
| ID | Name | Gender | Marks | Grade |
|---|---|---|---|---|
| 001 | Alex | M | 488 | AA |
| 002 | James | M | 478 | +A |
| 003 | Mary | F | 475 | +A |
| 004 | Robert | M | 466 | A |
| 005 | Elizabeth | F | 459 | A |
Popular RDBMS Software
| Software | Description |
|---|---|
| MySQL | Open-source, widely used in web apps |
| PostgreSQL | Advanced open-source with rich features |
| Oracle Database | Commercial, enterprise-grade |
| Microsoft SQL Server | Microsoft’s RDBMS for Windows & Azure |
| SQLite | Lightweight, used in mobile/web apps |
RDBMS vs DBMS
| RDBMS | DBMS |
|---|---|
| Data stored is in table format | Data stored is in the file format |
| Multiple data elements are accessible together | Individual access of data elements |
| Data in the form of a table are linked together | No connection between data |
| Normalization is present in RDBMS. | Normalization is not present in DBMS. |
| Support distributed database | No support for distributed database |
| Data is stored in a large amount | Data stored is a small quantity |
| Here, redundancy of data is reduced with the help of key and indexes in RDBMS | Data redundancy is common |
| RDBMS supports multiple users | DBMS supports a single user |
| It features multiple layers of security while handling data | There is only low security while handling data |
| The software and hardware requirements are higher | The software and hardware requirements are low |
| Example: Oracle, SQL Server. | Example: mysql, postgre, sql server, oracle etc. |
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