SQL (Structured Query Language) is the standard language for managing and querying relational databases. Developed at IBM in the 1970s as part of the System R project, SQL became an industry standard and remains the dominant interface for database systems worldwide.
Origins
Donald Chamberlin and Raymond Boyce at IBM San Jose Research Laboratory designed SQL (originally called SEQUEL—Structured English Query Language) to provide a practical interface to Edgar Codd’s relational model. Their goal was a language that non-programmers could use to retrieve and manipulate data[1].
The name was shortened to SQL due to trademark conflicts with an existing SEQUEL product.
Revolutionary Approach
SQL introduced declarative programming to data management:
Declarative, Not Procedural: Users specify what data they want, not how to get it. SELECT name FROM employees WHERE salary > 50000 describes the desired result; the database determines the optimal retrieval method.
Set-Based Operations: SQL operates on sets of rows rather than individual records, making bulk operations natural and efficient.
English-Like Syntax: Keywords like SELECT, FROM, WHERE, JOIN, and ORDER BY were chosen to be readable by non-programmers.
Core Operations
SQL encompasses several categories of commands:
- Data Query Language (DQL): SELECT statements for retrieving data
- Data Manipulation Language (DML): INSERT, UPDATE, DELETE for modifying data
- Data Definition Language (DDL): CREATE, ALTER, DROP for defining schema
- Data Control Language (DCL): GRANT, REVOKE for access control
Standardization
SQL became an ANSI standard in 1986 and an ISO standard in 1987. Subsequent revisions added features:
- SQL-89: Minor revision
- SQL-92: Major expansion with new data types
- SQL:1999: Object-relational features, recursive queries
- SQL:2003: XML support, window functions
- SQL:2011: Temporal data
- SQL:2016: JSON support
Ubiquity
Every major relational database implements SQL: Oracle, MySQL, PostgreSQL, Microsoft SQL Server, SQLite, and dozens more. While each vendor adds proprietary extensions, core SQL remains remarkably consistent. Knowing SQL provides access to virtually any relational database system[2].
Even non-relational systems increasingly support SQL or SQL-like interfaces, recognizing its value as a lingua franca for data.
Sources
- Chamberlin, Donald. “Early History of SQL.” IEEE Annals of the History of Computing, 2012.
- Wikipedia. “SQL.” Overview and history.