SQL
SQL (Structured Query Language) is a structured query language designed for managing data in relational databases. It is used to create tables, modify their structure, insert and retrieve data, perform analytical queries, manage transactions, and control access. SQL is based on formal logic and relational algebra principles, which ensures precision and predictable behavior when working with large datasets.
How SQL works
SQL operates through interaction between a client and a database management system (DBMS). An application sends a query to the database server, after which the DBMS analyzes it, optimizes it, generates an execution plan, and returns the result. SQL queries are declarative: the developer specifies what to retrieve, not how to retrieve it. Determining the optimal execution strategy is the responsibility of the DBMS. This makes SQL easier to use, universal, and independent of the underlying processing mechanisms.
Core capabilities of SQL
SQL provides four key groups of operations:
- DDL – create and modify data structures (CREATE, ALTER, DROP)
- DML – insert, update, and delete data (INSERT, UPDATE, DELETE)
- DQL – read data (SELECT)
- DCL and TCL – manage access and transactions (GRANT, COMMIT, ROLLBACK)
SQL supports aggregation, sorting, filtering, table joins, subqueries, and index-based operations. This makes it a fundamental tool in analytics, development, DevOps, data engineering, and enterprise systems.
Where SQL is used
SQL is used in any system that relies on relational databases: corporate ERP and CRM platforms, banking systems, government information systems, cloud services, e-commerce applications, and analytical data warehouses. Even when using ORM tools, developers implicitly work with SQL, since this language underpins most DBMSs — PostgreSQL, MySQL, Oracle, SQL Server, and others.
Benefits
- standardization and portability across systems
- high expressiveness
- query optimization performed by the DBMS
- mature ecosystem and analytical tools
- reliable transactions and ACID support
SQL remains a key technology for working with data despite the rise of NoSQL systems. Its universality and stability make it indispensable in most data management infrastructures.
FAQ
SQL allows you to create data structures, modify them, insert records, perform complex queries, analyze data, and manage transactions.
SQL is considered a declarative query language rather than a traditional programming language. It describes the desired result rather than a sequence of steps.
The core standard is the same, but each DBMS adds its own extensions—for example, PostgreSQL functions or Oracle’s windowing features. However, the basic constructs remain consistent.
SQL works with relational tables and strict schemas, while NoSQL systems may be document-based, graph-based, or key–value stores. SQL is preferred where structure and transactional reliability are important.
Yes. Many analytical platforms (BigQuery, ClickHouse, Spark SQL) use SQL as the interface for processing massive datasets.
