SQL (Structured Query Language) is a programming language used for data management and querying in relational database management systems (RDBMS). SQL is used to perform various functions of database management systems (DBMS), such as creating databases, adding data to databases, retrieving data from databases, updating data in databases, and deleting data from databases.
SQL is used to define the table structure used in relational databases. It creates these tables, defines data types, adds, updates, and deletes columns and rows. Additionally, SQL is used to define relationships between tables.
The fundamental components of SQL include:
DDL (Data Definition Language): DDL is used to define and manage database objects. Commands like CREATE, ALTER, and DROP are part of DDL.
DML (Data Manipulation Language): DML is used to query, add, update, and delete data in the database. Commands like SELECT, INSERT, UPDATE, and DELETE are part of DML.
DCL (Data Control Language): DCL is used to manage database security. Commands like GRANT and REVOKE are part of DCL.
TCL (Transaction Control Language): TCL is used to manage database transactions. Commands like COMMIT, ROLLBACK, and SAVEPOINT are part of TCL.
SQL is a widely used standard in databases and is supported by many different RDBMS. Popular RDBMS like Oracle, MySQL, Microsoft SQL Server, PostgreSQL, and SQLite use the SQL language.