What is SQL Language? Subset of SQL

 

What is SQL Language?

SQL is a database management language designed by Donald D.Chamberlin Raymond F.Boyce in 1974.SQL stands for Structured Query Language, which is used to perform various operations in a relational database management system. It is one of the fourth-generation programming languages used to handle and retrieve data from the database. 

Learning SQL language is easy for anyone with prior knowledge about another programming language. Apart from SQL, the various databases include Oracle, MariaDB, MSSQL, MySQL, and PostgreSQL. Developers widely use SQL because it adapts to any database, which helps users access their records whenever needed.

Subsets in SQL

The subsets of SQL are subdivided into four types.  

Data Control Language

As the name suggests, data control language manages the permission and right to access the database management system. The two main commands used in DCL are,

GRANT-This command permits the user to access the database objects

REVOKE-This command acts opposite to the previous command, where it withdraws the access permission provided by the Grant command.

Data Manipulation Language

The SQL commands which deals with the manipulation of record or data in a database is termed Data Manipulation Language. The various types of queries used in DML are,

INSERT-This command is used to insert the data or record in the table.

UPDATE- This command is used to update the data or record in the table, which is already present, called existing data.

DELETE-This command is used to delete the data or record from the table.

SELECT INTO-This command is used to select the concerned data from one table and insert it into the other table.

CALL-The process of calling a sub-program which includes Java or SQL.

LOCK- The lock command is used to lock the particular data, so only one user is allowed to change the data, which stops multiple database users from modifying the same data.

EXPLAIN PLAN-The path to the data is described here where users easily access the data.

Data Definition Language

The Data Definition language is used to define the database system. It is used to represent the structure of the database. The functions include create, modify, alter etc., which are used to design the database, not able to modify the data. The commands include,

CREATE- The process of creating the database includes tables, indexes, views, functions, and procedures.

ALTER-The structure of the database is altered by using alter command.

DROP-The drop command is used to delete the objects from the database.

COMMENT-In the data dictionary, the regarding comment is added.

RENAME-It is used to rename the object already present in the database.

TRUNCATE-All the records or data has been removed, including spaces using the truncate command.

TRANSACTION CONTROL LANGUAGE

As the name suggests, Transaction control language is for the process of handling transactions with the database management system. By using TCL commands, the objects are executed in a single unit.

COMMIT-It is used to commit the database, where the commit command is used after the necessary changes are made to the database. Once this command is used, the database can't roll back to its previous state.

ROLLBACK- The rollback transaction helps the database return to its previous state by cancelling the concerned transaction set. If some data are deleted unknowingly, or some error occurs, the rollback commands help revert the data.

The SAVEPOINT-Save point helps roll back to the previous state for the desired data without changing the whole data. The entire transaction in a table is not affected. Only the particular data is transacted back.

SET TRANSACTION initiates the transaction for the current data or record, enabling read-only or read-write. It does not affect other transactions or other users.

Feature of SQL

Creating the Database-Using SQL, one can create the database used for storing, retrieving, and manipulating the data. To get the desired output, it is easy to combine two tables.

Accessing the database- The database users are granted permission to access the database to implement various functions.

Managing the database-It is mandatory to manage the database, as large business sectors and companies widely use it. Handling large sets of data is a large task.

Database Manipulation-Manipulation in the terms referred to create, alter, modify, delete etc., are some of the functions used to make changes in the data.

Website Usage-SQL is a programming language which is integrated with another programming language. To embed SQL in other programming languages has some extensions.

Summary

In this technological and digital world, the amount of data is increasing daily. Handling and managing large sets of data is a challenging one. A database management system helps the users store and retrieve their data whenever needed. Both pros and cons are in a database management system. It is inevitable to use database management to maintain large sets of data.