SQL stands for Structured Query Language. It is a domain-specific programming language used for managing and manipulating relational databases. SQL provides a standardized syntax and set of commands for performing various operations on databases, including:-
1. Data Querying:- SQL allows users to retrieve data from a database using the SELECT statement. Users can specify criteria to filter the data and sort the results as needed.
2. Data Manipulation:- SQL supports commands for inserting new records into a database (INSERT), updating existing records (UPDATE), and deleting records (DELETE).
3. Data Definition:- SQL provides commands for defining and modifying the structure of a database, including creating and altering tables (CREATE TABLE, ALTER TABLE), defining indexes (CREATE INDEX), and establishing relationships between tables (ALTER TABLE, FOREIGN KEY).
4. Data Control:- SQL includes commands for managing user access and permissions to the database objects. This includes granting and revoking privileges (GRANT, REVOKE) to perform specific operations on tables and other database objects.
5. Data Transactions:- SQL supports transaction control commands to ensure data integrity and consistency. This includes starting and committing transactions (BEGIN TRANSACTION, COMMIT), as well as rolling back transactions in case of errors (ROLLBACK).
6. Data Constraints:- SQL allows users to define constraints on the data to enforce rules and ensure data integrity. This includes constraints such as NOT NULL, UNIQUE, PRIMARY KEY, FOREIGN KEY, and CHECK constraints.
SQL is widely used in various applications and industries for interacting with relational databases, including web development, data analysis, business intelligence, and more. It is supported by most relational database management systems (RDBMS), including MySQL, PostgreSQL, Oracle Database, Microsoft SQL Server, SQLite, and others. While there are some dialectical differences between SQL implementations of different database systems, the core SQL syntax and functionality remain largely consistent across platforms.
