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SQL RDBMS Concepts

RDBMS stands for Relational Database Management Systems. It is called Relational Database Management System (RDBMS) because it is based on the relational model introduced by E.F. Codd. RDBMS stores the data into the collection of tables, which is related by common fields between the columns of the table. It also provides relational operators to manipulate the data stored in the tables.

RDBMS is the basis for SQL, and for all modern database systems like MS SQL Server, IBM DB2, Oracle, MySQL, and Microsoft Access.

History of RDBMS

RDBMS is originally based on E.F. Codd's relational model invention. From 1970 to 1972, E.F. Codd published a paper to propose the use of the relational database model.

Basic Features of RDMS

  • A relational database contains the number of tables and each table has its own primary key.
  • Data is represented in terms of rows (It is also known as a tuple) in RDBMS.
  • Due to a collection of an organized set of tables, data can be accessed easily in RDBMS.
  • Virtual tables are available for storing the insightful data
  • Numerous users can access it together which is managed by a single user
  • In order to exclusively find out the rows, the primary key is used

What is the table?

The RDBMS database uses tables to store data in database objects which are called tables. A table is the most common and simplest form of data storage in a relational database.

Example of a STUDENT Record table:

ID NAME AGE COURSE BRANCH
1 Rocky 23 B.Tech IT
2 Sonal 20 B.C.A IT/CS
3 Rohan 25 B.Tech EEE

What is the field?

Every table is broken up into smaller entities of the table which contains specific information about every record in the table; it is called fields. The above table consists of an ID, NAME, AGE, COURSE, and BRANCH.

What is a row or a record?

The row contains the specific information of each individual entry in the table. It is a horizontal entity in the table.

Example - STUDENT Table

1 Rocky 23 B.Tech IT

What is a column?

A table that contains all information associated with a specific field in a table. And a column is a vertical entity in the table.

Example:

Rocky
Sonal
Rohan

What is a NULL value?

The NULL value of the table specifies that the field has been left blank during record creation. It is very important to understand that a NULL value is different than a zero value or a field that contains spaces.

The Main Principles Of The RDBMS Model

Entity integrity: The entity integrity says that in a database, all the data should be organized having a single key. The uniqueness of all the data is maintained by this principle.

Referential integrity: Referential integrity means that in the database all table values stay true for all foreign keys.

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